NTP TECHNICAL REPORT
 

ON THE
 

TOXICOLOGY AND CARCINOGENESIS
 

STUDIES OF OXAZEPAM
 

(CAS NO. 604-75-1)
 

IN F344/N RATS
 

(FEED STUDIES)
 

NATIONAL TOXICOLOGY PROGRAM
 

P.O. Box 12233
 

Research Triangle Park, NC 27709
 

October 1998
 

NTP TR 468
 

NIH Publication No. 99-3958
 

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
 

Public Health Service
 

National Institutes of Health
 
FOREWORD 

The National Toxicology Program (NTP) is made up of four charter agencies of the U.S. Department of 

Health and Human Services (DHHS): the National Cancer Institute (NCI), National Institutes of Health; the 

National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health; the National 

Center for Toxicological Research (NCTR), Food and Drug Administration; and the National Institute for 

Occupational Safety and Health (NIOSH), Centers for Disease Control. In July 1981, the Carcinogenesis 

Bioassay Testing Program, NCI, was transferred to the NIEHS. The NTP coordinates the relevant 

programs, staff, and resources from these Public Health Service agencies relating to basic and applied 

research and to biological assay development and validation. 

The NTP develops, evaluates, and disseminates scientific information about potentially toxic and hazardous 

chemicals. This knowledge is used for protecting the health of the American people and for the primary 

prevention of disease. 

The studies described in this Technical Report were performed under the direction of the NIEHS and were 

conducted in compliance with NTP laboratory health and safety requirements and must meet or exceed all 

applicable federal, state, and local health and safety regulations. Animal care and use were in accordance 

with the Public Health Service Policy on Humane Care and Use of Animals. The prechronic and chronic 

studies were conducted in compliance with Food and Drug Administration (FDA) Good Laboratory Practice 

Regulations, and all aspects of the chronic studies were subjected to retrospective quality assurance audits 

before being presented for public review. 

These studies are designed and conducted to characterize and evaluate the toxicologic potential, including 

carcinogenic activity, of selected chemicals in laboratory animals (usually two species, rats and mice). 

Chemicals selected for NTP toxicology and carcinogenesis studies are chosen primarily on the bases of 

human exposure, level of production, and chemical structure. The interpretive conclusions presented in this 

Technical Report are based only on the results of these NTP studies. Extrapolation of these results to other 

species and quantitative risk analyses for humans require wider analyses beyond the purview of these studies. 

Selection per se is not an indicator of a chemical’s carcinogenic potential. 

Listings of all published NTP reports and ongoing studies are available from NTP Central Data 

Management, NIEHS, P.O. Box 12233, MD E1-02, Research Triangle Park, NC 27709 (919-541-3419). 

The Abstracts and other study information for 2-year studies are also available at the NTP’s World Wide 

Web site: http://ntp-server.niehs.nih.gov. 
NTP TECHNICAL REPORT
 

ON THE
 

TOXICOLOGY AND CARCINOGENESIS
 

STUDIES OF OXAZEPAM
 

(CAS NO. 604-75-1)
 

IN F344/N RATS
 

(FEED STUDIES)
 

NATIONAL TOXICOLOGY PROGRAM
 

P.O. Box 12233
 

Research Triangle Park, NC 27709
 

October 1998
 

NTP TR 468
 

NIH Publication No. 99-3958
 

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
 

Public Health Service
 

National Institutes of Health
 
2 Oxazepam, NTP TR 468 

CONTRIBUTORS
 

National Toxicology Program 

Evaluated and interpreted results and reported findings 

J.R. Bucher, Ph.D., Study Scientist 

D.A. Bridge, B.S. 

R.E. Chapin, Ph.D. 

J.R. Hailey, D.V.M. 

J.K. Haseman, Ph.D. 

R.A. Herbert, D.V.M., Ph.D. 

R.R. Maronpot, D.V.M. 

G.N. Rao, D.V.M., Ph.D. 

J.H. Roycroft, Ph.D. 

C.S. Smith, Ph.D. 

G.S. Travlos, D.V.M. 

D.B. Walters, Ph.D. 

K.L. Witt, M.S., Oak Ridge Associated Universities 

Battelle Columbus Laboratories 

Conducted studies, evaluated pathology findings 

P.J. Kurtz, Ph.D., Principal Investigator 

M. Hejtmancik, Ph.D. 

M.J. Ryan, D.V.M., Ph.D. 

Experimental Pathology Laboratories, Inc. 

Provided pathology quality assurance 

J.F. Hardisty, D.V.M., Principal Investigator 

C.C. Shackelford, D.V.M., M.S., Ph.D. 

Dynamac Corporation 

Prepared quality assurance audits 

S. Brecher, Ph.D., Principal Investigator 

NTP Pathology Working Group 

Evaluated slides, prepared pathology report on rats 

(3 April 1996) 

D.G. Goodman, V.M.D., Chairperson 

PATHCO, Inc. 

R. Brown, D.V.M. 

Glaxo-Wellcome 

J.R. Hailey, D.V.M. 

National Toxicology Program 

R.A. Herbert, D.V.M., Ph.D. 

National Toxicology Program 

A. Nyska, D.V.M. 

National Toxicology Program 

A. Radovsky, D.V.M., Ph.D. 

National Toxicology Program 

C.C. Shackelford, D.V.M., M.S., Ph.D. 

Experimental Pathology Laboratories, Inc. 

Analytical Sciences, Inc. 

Provided statistical analyses 

R.W. Morris, M.S., Principal Investigator 

S.R. Lloyd, M.S. 

N.G. Mintz, B.S. 

Biotechnical Services, Inc. 

Prepared Technical Report 

S.R. Gunnels, M.A., Principal Investigator 

J.M. Gregory, B.S. 

L.M. Harper, B.S. 

A.M. Macri-Hanson, M.A., M.F.A. 
3 

CONTENTS
 

ABSTRACT ............................................................. 5
 

EXPLANATION OF LEVELS OF EVIDENCE OF CARCINOGENIC ACTIVITY ............. 9
 

TECHNICAL REPORTS REVIEW SUBCOMMITTEE ................................ 10
 

SUMMARY OF TECHNICAL REPORTS REVIEW SUBCOMMITTEE COMMENTS .......... 11
 

INTRODUCTION ......................................................... 13
 

MATERIALS AND METHODS ................................................ 21
 

RESULTS ............................................................... 29
 

DISCUSSION AND CONCLUSIONS ............................................ 47
 

REFERENCES ........................................................... 51
 

APPENDIX A Summary of Lesions in Male Rats in the 2-Year Feed Study
 

of Oxazepam ................................................. 61
 

APPENDIX B Summary of Lesions in Female Rats in the 2-Year Feed Study
 

of Oxazepam ................................................. 109
 

APPENDIX C Genetic Toxicology ............................................. 147
 

APPENDIX D Chemical Characterization and Dose Formulation Studies ................... 155
 

APPENDIX E Feed and Compound Consumption in the 2-Year Feed Studies of Oxazepam ...... 163
 

APPENDIX F Ingredients, Nutrient Composition, and Contaminant Levels in NIH-07 Rat
 

and Mouse Ration .............................................. 169
 

APPENDIX G Sentinel Animal Program ......................................... 173
 

APPENDIX H Early Responses of F344/N Rats to Oxazepam ........................... 175
 
4 Oxazepam, NTP TR 468
 
5 

ABSTRACT
 

OXAZEPAM 

CAS No. 604-75-1 

Chemical Formula: C 15 11 2 2 H ClN O Molecular Weight: 286.74

Synonym: 7-Chloro-1,3-dihydro-3-hydroxy-5-phenyl-2H-1,4-benzodiazepin-2-one 

Trade Names: Serax, Tazepam, Wy-3498 

Oxazepam and related benzodiazepine drugs are used 

in the treatment of anxiety. All benzodiazepines 

currently in use share a number of effects, including 

sedation, hypnosis, decreased anxiety, muscle relaxation, amnesia, and anticonvulsant activity. Oxazepam 

and four other benzodiazepines (chlordiazepoxide, 

chlorazepate, diazepam, and flurazepam) were 

nominated for study by the Food and Drug 

Administration (FDA) and by the NIEHS based on 

their widespread use, use by pregnant women, and the 

lack of adequate rodent carcinogenicity studies. 

Oxazepam was evaluated in 14-week and 2-year 

studies by the NTP, and Technical Report No. 443 

contains the results of the studies performed with the 

Swiss-Webster and B6C3F strains of mice. Studies 1 

with rats were not initiated at the same time as the 

mouse studies because adequate carcinogenicity studies 

of oxazepam with the Sprague-Dawley rat strain had 

been submitted to the FDA. Subsequently, because of 

the marked neoplastic responses found in the two 

mouse strains, the NTP initiated 2-year studies of 

oxazepam with the F344/N rat. Groups of male 

and female F344/N rats were exposed to oxazepam 

(greater than 99% pure) in feed for 2 years. Genetic 

toxicology studies were conducted in Salmonella 

typhimurium and cultured Chinese hamster ovary cells, 

and mouse peripheral blood samples were analyzed for 

the frequency of micronucleated normochromatic 

erythrocytes. 

2-YEAR STUDY 

Groups of 50 male and 50 female F344/N rats were 

fed diets containing 0, 625, 2,500, or 5,000 ppm 

oxazepam for up to 105 weeks. A stop-exposure 

group of 50 males and 50 females received 

10,000 ppm oxazepam in feed for 26 weeks, after 

which animals received undosed feed for the remainder of the 2-year study. The continuous-exposure 

concentrations resulted in average daily doses of 25, 

100, or 250 mg oxazepam/kg body weight to males 

and 25, 110, or 220 mg/kg to females. Stop- exposure 

males and females received an average daily dose of 

630 mg/kg during the exposure period. 
6 Oxazepam, NTP TR 468 

Survival, Body Weights, 

and Clinical Findings 

All 5,000 ppm continuous-exposure and 10,000 ppm 

stop-exposure males died before the end of the study. 

Survival of 2,500 ppm continuous-exposure males and 

females was significantly less than that of the controls. 

The mean body weight gains of 2,500 and 5,000 ppm 

males and females were less than those of the controls 

throughout the study. The mean body weights of 

10,000 ppm stop-exposure males were generally less 

than those of the controls throughout the study; those 

of 10,000 ppm stop-exposure females were less than 

those of the controls during the exposure portion of 

the study but increased steadily after the cessation of 

dosing at week 27. Feed consumption by exposed 

groups was similar to that by the controls after week 1 

of the study. Treatment-related eye/nasal discharge, 

hyperactivity when handled, and/or ataxia were 

observed in exposed male and female rats on or about 

day 2 of exposure but were no longer apparent after 

day 7. 

Plasma Oxazepam Determinations 

Plasma oxazepam concentrations were measured at the 

end of the study. The concentrations ranged from 

approximately 0.5 (625 ppm males) to 2.8 Fg/mL 

(5,000 ppm females). 

Pathology Findings 

In the standard histopathologic evaluation, the incidence of renal tubule adenoma was slightly increased 

in male rats exposed to 2,500 ppm and was at the 

upper limit of the historical control range for this 

neoplasm in 2-year NTP feed studies. In an extended 

evaluation (step section) of the kidneys of male rats, 

the incidences of renal tubule adenoma occurred with 

a positive trend in exposed groups. In standard and 

step sections (combined), male rats exposed to 2,500 

or 5,000 ppm showed a significant increase in the 

incidences of renal tubule adenoma and hyperplasia. 

In addition, the incidences of renal tubule adenoma 

and hyperplasia were significantly increased in the 

10,000 ppm stop-exposure group. The incidences of 

nephropathy in continuously exposed female rats were 

significantly greater than in the controls, and the 

severity of nephropathy increased with increasing 

exposure concentration in males. 

The incidences of epithelial hyperplasia and chronic 

inflammation of the forestomach in males exposed to 

2,500 and 5,000 ppm and of ulcers in 2,500 ppm 

males were significantly greater than in the controls. 

Incidences of mineralization of the glandular stomach 

in 5,000 ppm and 10,000 ppm (stop-exposure) males 

and of erosion of the duodenum in 5,000 ppm males 

were significantly greater than in the controls. Female 

rats exposed to 2,500 ppm had greater incidences of 

epithelial hyperplasia, chronic inflammation, and 

ulcers of the forestomach and of erosion in the 

glandular stomach. 

Centrilobular hepatocyte hypertrophy occurred more 

frequently in 2,500 and 5,000 ppm males and females 

than in the controls. 

GENETIC TOXICOLOGY 

Oxazepam was not mutagenic in any of several strains 

of S. typhimurium, nor did it induce sister chromatid 

exchanges or chromosomal aberrations in cultured 

Chinese hamster ovary cells. These in vitro tests were 

performed with and without S9 metabolic activation. 

Results from an in vivo mouse peripheral blood 

micronucleus test performed on B6C3F mice used in 1

a 14-week study were also negative. 
 

__________ 

Oxazepam, NTP TR 468 7 

CONCLUSIONS 

In summary, under the conditions of these 2-year 

dosed-feed studies, there was equivocal evidence of 

carcinogenic activity* in male F344/N rats, based on 

small increases in the incidences of renal tubule 

adenomas in exposed groups also exhibiting significantly enhanced nephropathy. There was no evidence 

of carcinogenic activity of oxazepam in female F344/N 

rats exposed to feed containing 625, 2,500, or 

5,000 ppm for 2 years or 10,000 ppm for 6 months. 

Administration of oxazepam to rats resulted in nonneoplastic lesions in the forestomach, glandular 

stomach, and small intestine as well as centrilobular 

hypertrophy of hepatocytes in the liver. In addition, 

nephropathy was increased in incidence in female rats 

and was markedly increased in severity in male rats, 

resulting in early mortality at the higher exposure 

concentrations. 

* Explanation of Levels of Evidence of Carcinogenic Activity is on page 9. A summary of the Technical Reports Review Subcommittee

 comments and the public discussion on this Technical Report appears on page 11. 
8 Oxazepam, NTP TR 468 

Summary of the 2-Year Carcinogenesis and Genetic Toxicology Studies of Oxazepam 

Male F344/N Rats	 Female F344/N Rats 

(2-Year Study) (Stop-Exposure Study) (2-Year Study) (Stop-Exposure Study) 

Concentrations	 0, 625, 2,500, or 10,000 ppm for 26 weeks 0, 625, 2,500, or 10,000 ppm for 26 weeks 

5,000 ppm 5,000 ppm 

Body weights	 2,500 ppm and 10,000 ppm group 2,500 and 5,000 ppm 10,000 ppm group similar 

5,000 ppm groups less generally less than control groups less than control to control group 

than control group group group 

2-Year survival rates	 17/50, 11/50, 6/50, 0/50 32/50, 26/50, 20/50, 25/50 

0/50 31/50 

Nonneoplastic effects	 Kidney: severity of Kidney: severity of Kidney: nephropathy Forestomach: chronic 

nephropathy (1.9, 2.3, nephropathy (3.3) (32/50, 43/50, 41/50, inflammation (5/50); ulcer 

2.7, 3.2) 48/50) (4/50); epithelial 

Forestomach: chronic hyperplasia (5/50) 

Forestomach: chronic inflammation (10/49); Forestomach: chronic 

inflammation (6/50, 8/48, ulcer (7/49); epithelial inflammation (1/50, 5/50, 

23/50, 15/50); ulcer hyperplasia (15/49) 16/50, 3/50); ulcer (1/50, 

(9/50, 12/48, 20/50, 2/50, 9/50, 6/50); 

10/50); epithelial Glandular stomach: epithelial hyperplasia 

hyperplasia (5/50, 8/48, mineralization (16/47) (2/50, 6/50, 16/50, 5/50) 

25/50, 16/50) 

Glandular stomach: 

Glandular stomach: erosion (0/50, 4/50, 7/50, 

mineralization (0/50, 2/50) 

3/48, 1/50, 4/50) 

Liver: hepatocyte 

Small intestine: centrilobular hypertrophy 

duodenum, erosion (4/50, (0/50, 0/50, 10/50, 

3/48, 9/49, 16/50) 31/50) 

Liver: hepatocyte
 

centrilobular hypertrophy
 

(0/50, 1/50, 8/49, 14/50)
 

Neoplastic effects	 None None None None 

Uncertain findings	 Kidney: renal tubule Kidney: renal tubule None None 

adenoma (extended adenoma (extended 

evaluation - 1/50, 1/50, evaluation - 6/45; 

4/50, 5/50; standard and standard and extended 

extended evaluations evaluations combined ­

combined - 2/50, 1/50, 6/45) 

7/50, 6/50) 

Level of evidence Equivocal evidence No evidence 

of carcinogenic activity 

Genetic toxicology 

Salmonella typhimurium gene mutations: Negative with and without S9 in strains TA97, TA98, TA100, 

TA102, and TA1535 

Sister chromatid exchanges 

Cultured Chinese hamster ovary cells in vitro: Negative with and without S9 

Chromosomal aberrations 

Cultured Chinese hamster ovary cells in vitro: Negative with and without S9 

Micronucleated normochromatic erythrocytes 

in B6C3F1 mice: Negative at 14 weeks
Oxazepam, NTP TR 468 9 

EXPLANATION OF LEVELS OF EVIDENCE OF CARCINOGENIC ACTIVITY 

The National Toxicology Program describes the results of individual experiments on a chemical agent and notes the strength of the evidence 

for conclusions regarding each study. Negative results, in which the study animals do not have a greater incidence of neoplasia than control 

animals, do not necessarily mean that a chemical is not a carcinogen, inasmuch as the experiments are conducted under a limited set of 

conditions. Positive results demonstrate that a chemical is carcinogenic for laboratory animals under the conditions of the study and indicate 

that exposure to the chemical has the potential for hazard to humans. Other organizations, such as the International Agency for Research on 

Cancer, assign a strength of evidence for conclusions based on an examination of all available evidence, including animal studies such as 

those conducted by the NTP, epidemiologic studies, and estimates of exposure. Thus, the actual determination of risk to humans from 

chemicals found to be carcinogenic in laboratory animals requires a wider analysis that extends beyond the purview of these studies. 

Five categories of evidence of carcinogenic activity are used in the Technical Report series to summarize the strength of the evidence 

observed in each experiment: two categories for positive results (clear evidence and some evidence); one category for uncertain findings 

(equivocal evidence); one category for no observable effects (no evidence); and one category for experiments that cannot be evaluated 

because of major flaws (inadequate study). These categories of interpretative conclusions were first adopted in June 1983 and then revised 

in March 1986 for use in the Technical Report series to incorporate more specifically the concept of actual weight of evidence of 

carcinogenic activity. For each separate experiment (male rats, female rats, male mice, female mice), one of the following five categories is 

selected to describe the findings. These categories refer to the strength of the experimental evidence and not to potency or mechanism. 

•	 Clear evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a dose-related 

(i) increase of malignant neoplasms, (ii) increase of a combination of malignant and benign neoplasms, or (iii) marked increase 

of benign neoplasms if there is an indication from this or other studies of the ability of such tumors to progress to malignancy. 

•	 Some evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a chemical-related increased 

incidence of neoplasms (malignant, benign, or combined) in which the strength of the response is less than that required for clear 

evidence. 

•	 Equivocal evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a marginal increase of 

neoplasms that may be chemical related. 

•	 No evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing no chemical-related increases in 

malignant or benign neoplasms. 

•	 Inadequate study of carcinogenic activity is demonstrated by studies that, because of major qualitative or quantitative
 

limitations, cannot be interpreted as valid for showing either the presence or absence of carcinogenic activity.
 

When a conclusion statement for a particular experiment is selected, consideration must be given to key factors that would extend the actual 

boundary of an individual category of evidence. Such consideration should allow for incorporation of scientific experience and current 

understanding of long-term carcinogenesis studies in laboratory animals, especially for those evaluations that may be on the borderline 

between two adjacent levels. These considerations should include: 

• adequacy of the experimental design and conduct;
 

• occurrence of common versus uncommon neoplasia;
 

•	 progression (or lack thereof) from benign to malignant neoplasia as well as from preneoplastic to neoplastic lesions; 

•	 some benign neoplasms have the capacity to regress but others (of the same morphologic type) progress. At present, it is 

impossible to identify the difference. Therefore, where progression is known to be a possibility, the most prudent course is to 

assume that benign neoplasms of those types have the potential to become malignant; 

•	 combining benign and malignant tumor incidence known or thought to represent stages of progression in the same organ or 

tissue; 

•	 latency in tumor induction; 

•	 multiplicity in site-specific neoplasia; 

•	 metastases; 

•	 supporting information from proliferative lesions (hyperplasia) in the same site of neoplasia or in other experiments (same lesion 

in another sex or species); 

•	 presence or absence of dose relationships; 

•	 statistical significance of the observed tumor increase; 

•	 concurrent control tumor incidence as well as the historical control rate and variability for a specific neoplasm; 

•	 survival-adjusted analyses and false positive or false negative concerns; 

•	 structure-activity correlations; and 

•	 in some cases, genetic toxicology. 
________ 

10 Oxazepam, NTP TR 468 

NATIONAL TOXICOLOGY PROGRAM BOARD OF SCIENTIFIC COUNSELORS 

TECHNICAL REPORTS REVIEW SUBCOMMITTEE 

The members of the Technical Reports Review Subcommittee who evaluated the draft NTP Technical Report on oxazepam on 

11 December 1996 are listed below. Subcommittee members serve as independent scientists, not as representatives of any institution, 

company, or governmental agency. In this capacity, subcommittee members have five major responsibilities in reviewing the NTP studies: 

• to ascertain that all relevant literature data have been adequately cited and interpreted, 

• to determine if the design and conditions of the NTP studies were appropriate, 

• to ensure that the Technical Report presents the experimental results and conclusions fully and clearly, 

• to judge the significance of the experimental results by scientific criteria, and 

• to assess the evaluation of the evidence of carcinogenic activity and other observed toxic responses. 

Gary P. Carlson, Ph.D., Chairperson Irma Russo, M.D. 

School of Health Sciences Fox Chase Cancer Center 

Purdue University Philadelphia, PA 

West Lafayette, IN 

Arnold L. Brown, M.D., Principal Reviewer 

Louise Ryan, Ph.D.* 

Division of Biostatistics 

University of Wisconsin Medical School Dana-Farber Cancer Institute 

Madison, WI Boston, MA 

Thomas L. Goldsworthy, Ph.D. Robert E. Taylor, M.D., Ph.D., Principal Reviewer 

Department of Experimental Pathology and Toxicology Department of Pharmacology 

Chemical Industry Institute of Toxicology Howard University College of Medicine 

Research Triangle Park, NC Washington, DC 

Robert LeBoeuf, Ph.D. Frederick L. Tyson 

Corporate Professional and Regulatory Services St. Mary’s Hospital and Medical Center 

Human Safety Department Cancer Research Institute 

The Procter & Gamble Company Grand Junction, CO 

Cincinnati, OH 

Janardan K. Reddy, M.D. 

Jerrold M. Ward, D.V.M., Ph.D. 

National Cancer Institute 

Department of Pathology Frederick, MD 

Northwestern University Medical School 

Chicago, IL 

* Did not attend 
Oxazepam, NTP TR 468 11 

SUMMARY OF TECHNICAL REPORTS REVIEW SUBCOMMITTEE COMMENTS
 

On 11 December 1996, the draft Technical Report on 

the toxicology and carcinogenesis studies of oxazepam 

received public review by the National Toxicology 

Program’s Board of Scientific Counselors’ Technical 

Reports Review Subcommittee. The review meeting 

was held at the National Institute of Environmental 

Health Sciences, Research Triangle Park, NC. 

Dr. J.R. Bucher, NIEHS, introduced the toxicology 

and carcinogenesis studies of oxazepam by discussing 

the uses of the chemical and the rationale for study, 

describing the experimental design, reporting on 

survival and body weight effects, and commenting on 

compound-related neoplastic and nonneoplastic lesions 

in rats. Dr. Bucher noted that the Subcommittee had 

reviewed a bioassay of oxazepam in Swiss-Webster 

and B6C3F mice in 1993. The proposed conclusions 1 

for the present study were some evidence of carcinogenic activity in male F344/N rats and no evidence of 

carcinogenic activity in female F344/N rats. 

Dr. Taylor, a principal reviewer, agreed in principle 

with the proposed conclusions. He stated that because 

there was substantial reduction in body weight gain 

and survival in 2,500 and 5,000 ppm male rats along 

with a dose response that was not very dramatic, he 

would argue for changing the proposed conclusion in 

male rats to equivocal evidence of carcinogenic 

activity. Noting the figure illustrating the metabolism 

of oxazepam in F344 rats, Dr. Taylor stated that some 

discussion of metabolism in rats and mice would be 

useful as an aid in trying to explain the difference 

between the mouse and rat in sites of toxicity and 

neoplasia. 

Dr. Brown, the second principal reviewer, agreed with 

the proposed conclusions. He said that it would be 

helpful if additional information could be provided in 

the Abstract regarding the background against which 

this bioassay was conducted, i.e., the unpublished 

study by industry in Sprague-Dawley rats. Dr. Bucher 

observed that the 1996 edition of the Physicians’ Desk 

Reference provides a description of the rat study 

performed by Wyeth Laboratories, although no doses 

are listed. The citation indicates that there were 

increased incidences of prostate adenoma, interstitial 

cell adenoma of the testes, and thyroid gland follicular 

cell adenoma, none of which were replicated in the 

current study in F344/N rats. Dr. W.R. Allaben, 

NCTR/FDA, pointed out that the data are considered 

proprietary information and by law cannot be released 

publicly. Dr. Bucher mentioned that this was one of 

four benzodiazepines nominated and selected for 

study. Three were products of Hoffmann-LaRoche, 

which agreed to carry out the studies with the NTP’s 

assistance in the study design. The studies were 

completed, and data were submitted to the FDA. 

There was a discussion about the appropriateness 

of step sectioning kidneys in male rats and about 

the exposure concentrations used in the study. 

Dr. Bucher said that in retrospect, the 1,250 ppm 

group, which was terminated after 26 weeks with the 

thought that it would be uninformative, would have 

been the best high exposure group. Dr. LeBoeuf 

argued that if the 5,000 ppm group were excluded 

from analysis because of very poor survival, and if the 

results for renal tubule adenomas in the 625 and 

2,500 ppm groups were compared with those in 

the controls, then he would conclude that there 

was equivocal evidence of carcinogenic activity. 

Dr. J.K. Haseman, NIEHS, noted that the increased 

incidence of renal tubule adenoma in the 2,500 ppm 

group was significant at P=0.018. Dr. Goldsworthy 

asked under what circumstances the NTP would 

consider a study to be inadequate for evaluation. 

Dr. Bucher said that, generally, the NTP might 

consider a study to be inadequate if there is poor 

survival and if there is no neoplasm response, such 

that the ability of the study to detect a response may be 

compromised. Dr. Goldsworthy asked whether 

excluding a 13-week study would occur more often in 

future bioassays. Dr. G.A. Boorman, NIEHS, pointed 

out that in the case of oxazepam, a 26-week study did 

not predict very well; however, the decision of 

whether to employ a 13-week study would have to be 

determined on a case-by-case basis by drawing on 

other available toxicity information. 

Dr. Taylor moved that the Technical Report on 

oxazepam be accepted with the revisions discussed and 

the conclusion as written for female rats, no evidence 

of carcinogenic activity, but changed for male rats, 

from some evidence of carcinogenic activity to 

equivocal evidence of carcinogenic activity. 
12 Oxazepam, NTP TR 468 

Dr. Brown seconded the motion. In discussion, chemically induced because the organ is a target site 

Dr. Ward stated that having toxicity in an organ such for the chemical. Dr. Taylor’s motion was accepted 

as the kidney, where there were also neoplasms, with five yes votes to three no votes (Goldsworthy, 

strengthened the evidence for the neoplasms being Reddy, and Ward). 
 

13 

INTRODUCTION
 

OXAZEPAM 

CAS No. 604-75-1 

Chemical Formula: C 15 11 2 2 H ClN O Molecular Weight: 286.74

Synonym: 7-Chloro-1,3-dihydro-3-hydroxy-5-phenyl-2H-1,4-benzodiazepin-2-one 

Trade Names: Serax, Tazepam, Wy-3498 

CHEMICAL 

AND PHYSICAL PROPERTIES 

Oxazepam is a bitter-tasting, white, crystalline powder 

that is insoluble in water but soluble in alcohol, 

chloroform, and ether (Remington’s Pharmaceutical 

Sciences, 1980). The material is nonhygroscopic and 

stable in light. It has a melting-point range of 205E to 

206E C (Merck Index, 1983). 

PRODUCTION, USE, 

AND HUMAN EXPOSURE 

Oxazepam and related benzodiazepine drugs are used 

in the treatment of anxiety. Most clinically useful 

drugs for this purpose are variants of the 

1,4-benzodiazepine structure (Figure 1) consisting of 

two aromatic rings and a 7-membered heterocycle. 

One of the aromatic rings is fused to the 7-membered 

ring and contains a chlorine or other electronegative 

group as a substituent. All clinically important derivatives contain a 5-aryl or 5-cyclohexenyl group. Most 

of the drugs vary in substituent groups at the 1 and 3 

positions (Goodman and Gilman’s, 1996). Oxazepam, 

known under the trade name Serax®, is produced 

and sold by Wyeth Laboratories and has been on the 

market since 1965. Generic forms produced by other 

manufacturers are also now available (PDR, 1996). 

No definite production data are available for oxazepam 

or for the benzodiazepine drugs; however, the use of 

benzodiazepines by the general population has been 

reported as 8% in the United Kingdom, 7% in the 

United States, and 8% to 10% in Norway (Pedersen 

and Lavik, 1991). In 1983, 2.6 million prescriptions 

for oxazepam were written in the United States, and 

oxazepam ranked 132nd and 125th in overall 

frequency of prescriptions written for all drugs in 

1984 and 1985, respectively (Anonymous, 1986; 

C. Baum correspondence, 1986). Oxazepam is also a 

common metabolite of several other benzodiazepines, 

some of which are more widely prescribed, including 

diazepam (Valium®). In 1983, 25.5 million prescriptions for diazepam were written in the United 

States, making it the fourth most prescribed drug, and 

although newer benzodiazepines are replacing some of 

the older drugs, over 2.3 million prescriptions for 

diazepam were still written in 1995 (Anonymous, 

1996). 
14 Oxazepam, NTP TR 468 

FIGURE 1 

1,4-Benzodiazepine Structure 

REGULATORY STATUS 

Benzodiazepines are prescription drugs regulated 

under the Food, Drug, and Cosmetic Act of 1938 and 

are on Schedule IV of the Drug Enforcement Administration Controlled Substances Code (Tocus et al., 

1983). Although production workers and dispensers 

are exposed to benzodiazepines, no workplace 

exposure limits have been recommended for these 

types of chemicals (ACGIH, 1996). Environmental 

contamination has not been shown. 

PHARMACOLOGY 

All benzodiazepines currently in use share a number of 

effects, including sedation, hypnosis, decreased 

anxiety, muscle relaxation, amnesia, and anti-convulsant activity. Benzodiazepines are considered 

central nervous system (CNS) depressants but are not 

general depressants and, within therapeutic dose 

ranges, all effects are related to specific CNS events 

(Goodman and Gilman’s, 1996). Each drug differs 

slightly within this spectrum of actions (e.g., 

flurazepam has a strong hypnotic effect in humans) 

(Randall et al., 1969). Other drugs are marketed 

specifically for use in obstetrics, for epilepsy, or for 

insomnia (CRM, 1980). These differences may reflect 

the different intrinsic affinities of the drugs for 

benzodiazepine receptors. In addition, the various 

drugs have different pharmacokinetics (Greenblatt and 

Shader, 1978; Eadie, 1984), and differences in disposition and rates of biotransformation may affect the 

spectrum of effects. Oxazepam is a relatively shortacting agent typically prescribed for relief of anxiety 

and given orally at dose levels of 10, 15, or 30 mg, 

three or four times per day (PDR, 1996). 

The therapeutic effects of the benzodiazepines are 

thought to be due to a receptor-mediated response that 

increases the efficiency of submaximal GABAergic 

transmission mediated by a variety of long-fiber 

neurons and interneurons in the CNS (Richards et al., 

1986). A GABAergic receptor protein complex has 

been isolated and cloned from brain tissue, and some 

information is known on subunit structure in relation 

to benzodiazepine binding (Goodman and Gilman’s, 

1996). This complex is associated with a chloride ion 

channel and has associated proteins that are separate 

binding sites for barbiturates and the benzodiazepines 

(Barnard et al., 1984). The benzodiazepine binding 

site is on the alpha subunit (Levitan et al., 1988). The 

clinically useful benzodiazepines likely all act to 

increase the binding of GABA to the GABA receptor 

complex rather than changing the kinetics of chloride 

conductance in relation to the amount of GABA bound 

(Rogers et al., 1994). GABAergic neurons are most 

concentrated in the substantia nigra, globus pallidus, 

and hypothalamus in the human brain (Cooper et al., 

1978). However, the density of CNS-type benzodiazepine receptors is highest in the cortical regions of 

the cerebrum and cerebellum, suggesting other 

functions for the CNS-type receptors (Saano, 1988). 

The anxiety-reducing effect of benzodiazepines in the 

rat brain has been associated with GABAergic circuits 

in the mammillary body (Kataoka et al., 1982). At 

least one other benzodiazepine receptor type has been 

identified in the brain, specifically in glial tissues in 
Oxazepam, NTP TR 468 15 

the pineal gland and olfactory bulb, and is also found 

in heart, liver, lung, testis, and other tissues. The role 

of this receptor is not clear, but it appears to be a 

mitochondrial protein that may use porphyrins as 

endogenous ligands (Snyder et al., 1987; Verma and 

Snyder, 1989; Calvo et al., 1991) and may be 

involved in the regulation of steroid biosynthesis 

(Krueger and Papadopoulos, 1992), specifically in the 

transport of cholesterol to the inner mitochondrial 

membrane (Papadopoulos and Brown, 1995). Some 

structural requirements for binding to these receptors 

have been described (Campiani et al., 1996). 

ABSORPTION, DISPOSITION, 

METABOLISM, AND EXCRETION 

Experimental Animals 

The toxicokinetics and metabolism of oxazepam in 

F344 rats and B6C3F1 and Swiss-Webster mice have 

been described in detail by Yuan et al. (1994) and 

Griffin and Burka (1993, 1995). Oxazepam was well 

absorbed after oral administration, with peak blood 

concentrations achieved within 2 to 3.5 hours, and 

with female rats and mice having higher blood concentrations than males. Elimination of oxazepam from 

plasma was first order and best described by a twocompartment model with terminal elimination halflives of 4 to 5 hours for rats and 5 to 7 hours for 

mice. The bioavailability of oxazepam from the diet 

was about 40% of that achieved following a gavage 

dose of oxazepam (50 mg/kg) in methyl cellulose 

vehicle, and apparently decreased with increasing 

oxazepam concentrations. Thus, steady-state blood 

concentrations, reached after about 4 days on dosed 

feed, were not proportional to dose (Yuan et al., 

1994). 

The metabolism of oxazepam in the F344 rat is 

demonstrated in Figure 2. The metabolism of oxazepam is complex, with major pathways including ring 

oxidation through the dihydrodiol and conjugation 

with glucuronic acid or sulfate. A nonenzymatic 

condensation of the benzodiazepine ring also occurs. 

Not all metabolites have been identified. The metabolites are excreted primarily in feces and urine and 

appear in differing amounts depending on the size of 

the dose and the time of collection. In contrast to the 

mouse, pretreatment of rats with oxazepam did not 

significantly alter the metabolism or elimination 

profiles (Griffin and Burka, 1995). Pretreatment of 

mice tended to shift metabolites from feces to urine 

and increased excretion of glucuronide and unchanged 

drug. There was evidence of extensive enterohepatic 

circulation in the mouse (Griffin and Burka, 1993; 

Griffin et al., 1995a), and this may influence the 

ultimate metabolic profile in the mouse to a greater 

extent than in rats or humans. 

Humans 

Oxazepam is readily absorbed following oral administration, and peak blood levels in humans are 

achieved in 0.75 to 8 hours when oxazepam is given 

in tablet form, with an average of 2.7 hours (Shader 

and Greenblatt, 1981). The half-life of oxazepam in 

the blood of humans is 6.8 ± 1.3 hours. It has a 

volume of distribution of 0.6 ± 0.2 L/kg and a 

clearance of 1.05 ± 0.36 mL/min per kilogram. 

Approximately 98% of the drug is bound to plasma 

proteins (Goodman and Gilman’s, 1996). About 95% 

is converted to the C3 glucuronide conjugate by 

UDP glucuronyl transferase 2 (Rajaonarison et al., 

1991) and excreted in the urine; minor amounts of 

six other metabolites have been identified (Sisenwine 

et al., 1972). Only the parent compound is thought to 

have antianxiety activity. 

TOXICITY 

Experimental Animals 

Oral LD50 values for oxazepam have been reported to 

range from about 1,500 mg/kg to greater than 

5,000 mg/kg in various strains of mice (Marcucci 

et al., 1968; Randall et al., 1970; Scrollini et al., 

1975; Petrescu et al., 1981) and were greater than 

5,000 mg/kg in Wistar and Charles River CD rats 

(Owen et al., 1970; Scrollini et al., 1975). Owen 

et al. (1970) administered oxazepam in feed to Charles 

River CD rats at concentrations of 0.06%, 0.125%, 

0.25%, and 0.5%. After 6 weeks, 2 of 20 rats in the 

0.5% group died, and body weight gain was decreased 

in the 0.25% males. Liver, adrenal gland, and kidney 

weights were greater in exposed rats than in controls. 

The only histopathologic finding was an increase in 

liver parenchymal fat in exposed rats. 
 

16 Oxazepam, NTP TR 468 

FIGURE 2
 

Metabolism of Oxazepam in F344 Rats (Griffin and Burka, 1995)
 
Oxazepam, NTP TR 468 17 

Groups of 30 male and 30 female rats were fed diets 

containing 0, 0.015%, 0.03%, 0.06%, or 0.12% oxazepam for 55 weeks. Deaths were not clearly chemical 

related, and other than increased liver weights, no 

effects on body weight gain, hematology parameters, 

or significant chemical-related gross or histopathologic 

lesions were observed (Owen et al., 1970). 

The principal effects seen in Swiss-Webster and 

B6C3F mice in 13- or 14-week studies using dosed 1 

feed at concentrations as high as 10,000 ppm were 

marked liver weight increases and increased incidences 

of centrilobular hypertrophy. These changes occurred 

at all doses including the lowest dose, 625 ppm (NTP, 

1993). 

The increased liver weights observed in these and 

other studies with benzodiazepines suggest stimulation 

of proliferation of smooth endoplasmic reticulum 

(Orlandi et al., 1975). However, the benzodiazepines 

do not appear to stimulate their own metabolism and 

have been found to inhibit metabolism of other drugs 

such as morphine or aminopyrine in Wistar rats (Vega 

et al., 1984) and to stimulate metabolism of certain 

chemicals (i.e., benzene and aniline) (Jab»o1⁄2ska et al., 

1975). This coincides with the benzodiazepines’ 

reputation of not producing significant tolerance 

during long-term therapy (Goodman and Gilman’s, 

1996). Physical dependence has been demonstrated in 

rats with several of the drugs, including diazepam 

(Martin et al., 1982). 

Humans 

The benzodiazepines are a poor choice for suicide 

purposes and, despite many attempts, deaths by 

overdose are rare (Finkle et al., 1979; Buckley et al., 

1995). Overdoses of oxazepam commonly result in 

drowsiness, blurred vision, and ataxia. As in rats, 

stimulation of proliferation of smooth endoplasmic 

reticulum has been shown in liver biopsies from 

humans taking diazepam (Orlandi et al., 1975). 

Physical dependence is produced in humans given 

benzodiazepines. 

CARCINOGENICITY 

Experimental Animals 

Several long-term rodent studies have been performed 

with the benzodiazepines. Fox and Lahcen (1974) 

observed liver neoplasms in oxazepam-treated 

Swiss-Webster mice during the course of reproductive 

toxicity studies. Mice were housed as breeding pairs 

from 3 to 12 months of age and were fed an 

oxazepam-supplemented diet at doses of 0.05% and 

0.15%. They were killed at 14 months of age. The 

incidences of liver neoplasms increased in males (0/13, 

3/12, 8/13) and females (0/10, 0/10, 5/8) with dose. 

The neoplasms were generally multiple and gave the 

livers a massively nodular appearance. Histopathologically, the neoplasms were diagnosed as 

hepatocellular adenomas, which showed peliosis and 

extramedullary hematopoiesis. 

De la Iglesia et al. (1981) administered diazepam or 

prazepam in feed at concentrations sufficient to result 

in doses of up to 75 mg/kg body weight per day to 

male and female CF1 mice and Wistar rats for 80 and

104 weeks, respectively. The incidences of malignant 

liver neoplasms were increased in male mice receiving 

diazepam. Temazepam, which is metabolized to 

oxazepam in the mouse, was administered in feed to 

Charles River CD rats for 2 years and to Charles 

River CD-1 mice for 18 months at doses of 10 to 

160 mg/kg per day. Exposed female mice had slightly 

increased incidences of liver adenoma (Robinson 

et al., 1984). 

As a follow-up to the Fox and Lachen (1974) observation, groups of 60 male and 60 female SwissWebster mice were exposed to feed containing 0, 

2,500, or 5,000 ppm oxazepam for 57 weeks. The 

study was then terminated because of poor survival in 

the exposed groups. Mice receiving oxazepam were 

found to have very high rates of hepatocellular neoplasms (males, combined hepatocellular adenomas and 

carcinomas: control, 1/60; 2,500 ppm, 35/60; 

5,000 ppm, 52/60; females: 1/60, 23/59, 47/59), as 

well as an exacerbated amyloidosis. Amyloidosis is 

commonly seen in this strain of mice, but the condition 

was severe, particularly in the heart, and likely contributed to the low survival. A similar study was 

carried out with the B6C3F mouse, with an additional 1 

dose group receiving oxazepam at 125 ppm. This 

lower exposure concentration was projected to give 

blood concentrations in the therapeutic range for 

humans. Again, mice receiving 2,500 or 5,000 ppm 

oxazepam suffered from reduced survival and 

high rates of hepatocellular neoplasms (males, 

combined hepatocellular adenomas, carcinomas, and 

hepatoblastomas: control, 23/49; 125 ppm, 19/50; 

2,500 ppm, 50/50; 5,000 ppm, 50/50; females: 28/50, 

36/50, 50/50, 47/50). The incidences of thyroid gland 
18 Oxazepam, NTP TR 468 

follicular cell adenoma were also increased in exposed 

females (0/50, 4/50, 5/50, 6/50) (NTP, 1993; Bucher 

et al., 1994). 

Humans 

No studies on the carcinogenicity of oxazepam in 

humans were found in the literature. 

PROMOTION STUDIES 

The benzodiazepines have been tested in various 

promotion assays because of reports, primarily from 

one laboratory, that diazepam treatment accelerated the 

growth of intrarenally implanted neoplasm cells 

(Walker 256) (Horrobin et al., 1979) and that it was 

positive in an in vitro metabolic cooperation assay for 

neoplasm promoters (Trosko and Horrobin, 1980). 

These reports appeared following publication of an 

epidemiological study that suggested an association 

between increased incidences of breast cancer and 

benzodiazepine use in women (Stoll, 1976). This 

association was later discounted (Kleinerman et al., 

1984), but further animal experimentation has provided mixed results. 

Remandet et al. (1984) fed F344/N rats 

2-acetylaminofluorene for 8 weeks and followed this 

for 12 weeks with diets containing one of six benzodiazepines. They reported no increased incidences of 

liver neoplasms or enzyme-altered foci. Préat et al. 

(1987) reported positive promotional activity with 

oxazepam in Wistar rats in two different assays for 

hepatocarcinogenesis. In one, animals were initiated 

with diethylnitrosamine (DEN) and were treated with 

2-acetylaminofluorene and carbon tetrachloride during 

the next 2 weeks; they then received oxazepam in feed 

for 30 weeks. In the other protocol, initiation with 

DEN was preceded by partial hepatectomy, and 

promotion was effected by dietary administration for 

1 year. Diwan et al. (1986) found diazepam and 

oxazepam to be promoters of DEN-initiated liver 

neoplasms in mice. In this study, groups of B6C3F1 

mice received injections of DEN at 5 weeks of age; at 

7 weeks, they were fed diets containing diazepam or 

oxazepam at 0.05% or 0.15%, or were given phenobarbital in water at 500 ppm. Mice were killed 

periodically through 60 weeks of age. The incidences 

of neoplasms were increased in mice receiving diazepam and in those receiving 0.15% oxazepam. A few 

adenomas were also observed in uninitiated mice 

receiving 0.15% diazepam (3/15) or 0.05% oxazepam 

(2/16), and none were observed in mice receiving only 

phenobarbital. Diazepam and oxazepam were also 

found to induce hepatic P450 content and to increase 

aminopyrine N-demethylase activity. Diwan et al. 

(1986) have proposed that promotion of hepatocellular 

carcinogenesis is associated with induction of 

N-demethylase activity and appears to be quite species 

and strain specific. Diazepam did not induce cytochrome P450 in the liver of Sprague-Dawley rats 

(Vorne and Idänpään-Heikkilä, 1975), and this was 

considered consistent with the negative promotional 

findings of Remandet et al. (1984) in their study with 

F344/N rats. 

REPRODUCTIVE 

AND DEVELOPMENTAL TOXICITY 

Experimental Animals 

Although the benzodiazepines have been used in 

treating toxemia and preeclampsia as well as the 

psychiatric complications of pregnancy (Shannon 

et al., 1972; Kanto, 1982), there are many reports of 

fetotoxic and teratogenic effects of these and other 

minor tranquilizers when given to pregnant animals. 

Tucker (1985) provided a critical review of studies of 

developmental toxicity of benzodiazepines in the rat. 

Saito et al. (1984) found increases in fetal toxicity 

(resorptions, dead fetuses, and malformations) in 

pregnant rats given doses of diazepam or chlordiazepoxide of 100 mg/kg per os during gestational days 

7 to 14. Miller and Becker (1975) first found diazepam produced cleft palate following oral administration of 87.5 or 125 mg/kg to Swiss-Webster mice 

on days 11 to 13. This has since received considerable study and is now attributed to potentiation of 

the GABAergic inhibition of the palate shelf reorientation (Wee and Zimmerman, 1983). In general, 

exposures to high doses in utero produce decreased 

litter sizes, decreased pup weights, and increased 

numbers of malformations. Exposures to lower doses 

(5 to 20 mg/kg per day) during critical periods (after 

gestational day 14 in rats) produce no immediately 

obvious effects at birth but result in various behavioral 

deficits during later life and a variety of poorly understood changes in the concentration of neurotransmitters in various brain areas (Livezey et al., 

1986a; Ryan and Pappas, 1986; Shibuya et al., 1986). 

Central to these studies have been attempts to correlate 

changes in benzodiazepine receptor concentration with 

altered behavior. Livezey et al. (1986b) have argued 

that in utero exposure to benzodiazepines during the 
Oxazepam, NTP TR 468 19 

period of receptor development (after gestational day 

14 in rats) results in a decreased benzodiazepine 

receptor concentration and results in rats that suffer 

chronic anxiety demonstrated by hyperarousal, 

inability of the animals to habituate to a novel 

environment, and a large reduction in the amount of 

deep slow-wave sleep. Changes in passive avoidance 

have also been reported in mice following in utero 

exposure to oxazepam (Ricceri et al., 1994). 

Humans 

Exposure of the human fetus to diazepam results in a 

set of symptoms collectively known as the “floppy 

infant syndrome,” which includes hypothermia, hyperbilirubinemia, hypotonia, asphyxia, respiratory 

complications, and poor sucking response. This is 

likely due to the ready transfer of the drugs across the 

placenta. Pharmacologic effects are exaggerated in the 

unborn because higher levels accumulate due to the 

slower elimination from the fetus. There have been 

reports of increases in severe congenital anomalies in 

infants whose mothers took chlordiazepoxide and other 

benzodiazepines (including oxazepam) during 

pregnancy (Milkovich and van den Berg, 1974); there 

have also been reports claiming no link between 

benzodiazepine use and fetal abnormalities (Hartz 

et al., 1975). 

GENETIC TOXICITY 

Oxazepam has not been tested extensively for mutagenicity, but the data reported for oxazepam and its 

structural analogues indicate that this class of chemicals is probably not genotoxic. There is one report of 

a positive response in a Salmonella gene mutation 

assay (Batzinger et al., 1978). The authors described 

an increase in revertants for strains TA98 and TA100 

when exposure was carried out in the presence of rat 

liver S9 activation enzymes. The data reported were 

insufficient for a critical evaluation of the results. 

Other laboratories that have tested oxazepam for 

mutagenicity in Salmonella have reported negative 

results. Matula and Downie (1983), in a brief abstract 

which presented little experimental detail, reported 

negative results, with and without S9, in strains TA98 

and TA100. Balbi et al. (1980) detected no mutagenic 

activity with oxazepam in four strains of Salmonella, 

with or without S9, but their report did not include 

complete data tables for those tests that gave negative 

results. NTP mutagenicity tests with five strains of 

Salmonella yielded negative results, with and without 

S9 (Appendix C). 

No evidence of chromosome nondisjunction was 

observed in Aspergillus nidulans treated with an 

unspecified concentration of oxazepam in the absence 

of S9 (Bignami et al., 1974). Unscheduled DNA 

synthesis was not detected in rat liver cells in vitro 

(Swierenga et al., 1983), and no induction of chromosomal aberrations was observed in bone marrow cells 

of mice administered 0.85 mg/kg oxazepam by intraperitoneal injection five times weekly for 8 weeks 

(Degraeve et al., 1985). In addition, results from 

NTP (1993) studies (Appendix C) showed no induction of sister chromatid exchanges or chromosomal 

aberrations in cultured Chinese hamster ovary cells 

treated with oxazepam, with or without rat liver S9, 

and no increase in micronucleus frequency was noted 

in peripheral blood erythrocytes of male and female 

mice treated with oxazepam for 90 days. 

A variety of genotoxicity tests has been performed 

with two of the widely used structural analogues of 

oxazepam, diazepam, and chlordiazepoxide. Diazepam was nonmutagenic in Salmonella (Batzinger 

et al., 1978; Waskell, 1978; Preiss et al., 1982; 

Zeiger et al., 1992). There was no evidence of 

diazepam-induced chromosome loss or nondisjunction 

in yeast (Bignami et al., 1974; Matula and Downie, 

1983; Crebelli et al., 1989, 1991; Parry et al., 1989; 

Whittaker et al., 1989). The effects reported for 

diazepam in cultured mammalian cells varied. No 

induction of chromosomal aberrations was noted in 

cultured Chinese hamster ovary cells treated with 

diazepam with or without S9 in two laboratories 

(Ishidate et al., 1978; Matsuoka et al., 1979), but 

positive results were reported in one study using 

cultured Chinese hamster ovary cells treated in the 

absence of S9 (Lafi and Parry, 1988). Disruption of 

mitosis with concomitant chromosome loss was 

observed in cultured Chinese hamster ovary cells 

after treatment with diazepam in the absence of S9 

(Hsu et al., 1983; Parry et al., 1986; Lafi et al., 

1987). Results of tests for induction of chromosomal 

aberrations and sister chromatid exchanges in human 

lymphocytes (Staiger, 1970; Zhurkov, 1975) or 

fibroblasts (Staiger, 1969; Kawachi et al., 1980; 

Sasaki et al., 1980) treated in vitro with diazepam 

were uniformly negative. Unscheduled DNA synthesis was not detected in rat liver cells treated in vitro 
20 Oxazepam, NTP TR 468 

with diazepam (Swierenga et al., 1983; Williams 

et al., 1989). 

In vivo tests with diazepam showed little indication of 

genotoxic activity. No evidence of mitotic disruption 

or induction of chromosomal aberrations was observed 

in mouse bone marrow cells following administration 

of up to 100 or 150 mg/kg diazepam, respectively 

(Miller and Adler, 1989; Xu and Adler, 1990). 

Negative results were reported for diazepam in bone 

marrow chromosomal aberration assays in hamsters 

(Schmid and Staiger, 1969) and rats (Ishimura et al., 

1975; Kawachi et al., 1980). In addition, no increases 

in chromosomal aberrations (Stenchever et al., 1970a; 

White et al., 1974) or sister chromatid exchanges 

(Torigoe, 1979; Husum et al., 1985) were observed in 

peripheral lymphocytes obtained from patients treated 

with diazepam either chronically, as a management for 

anxiety or muscle spasm, or acutely, as part of a 

surgical routine. 

Fewer genotoxicity test results are available for 

chlordiazepoxide, but indications are that it, too, is not 

genetically active. Chlordiazepoxide did not induce 

nondisjunction in A. nidulans (Bignami et al., 1974) 

or chromosomal aberrations in cultured Chinese 

hamster cells (Sasaki et al., 1980), human fibroblasts 

(Staiger, 1969), or leucocytes (Bregman, 1970; 

Stenchever et al., 1970b). In vitro micronucleus tests 

with hamster and human cells were negative (Sasaki 

et al., 1980). Results of in vivo investigations indicate 

that chlordiazepoxide does not induce chromosomal 

aberrations in mouse (Petersen et al., 1978; 

Degraeve et al., 1985) or hamster (Schmid and 

Staiger, 1969) bone marrow cells. Finally, no induction of chromosomal aberrations was observed in 

lymphocytes obtained from patients administered 

chlordiazepoxide (up to 200 mg/day) (Stenchever 

et al., 1970b). 

STUDY RATIONALE 

Oxazepam and four other benzodiazepines (chlordiazepoxide, chlorazepate, diazepam, and flurazepam) 

were nominated for study by the Food and Drug 

Administration (FDA) and by the NIEHS based on 

their widespread use, use by pregnant women, and the 

lack of adequate rodent carcinogenicity studies. An 

agreement was reached with Hoffmann-LaRoche, Inc., 

the manufacturer of chlordiazepoxide, diazepam, and 

flurazepam, for studies to be carried out on these 

drugs under its auspices in cooperation with the NTP. 

These studies are completed and results have been 

submitted to the FDA. No studies were performed on 

chlorazepate because of the very similar metabolite 

profile between this drug and diazepam. Oxazepam 

was evaluated in 14-week and 2-year studies by the 

NTP, and Technical Report No. 443 contains the 

results of studies performed with the Swiss-Webster 

and B6C3F1 strains of mice (NTP, 1993). Studies 

with rats were not initiated at the same time as the 

mouse studies because adequate carcinogenicity studies 

of oxazepam with the Sprague-Dawley rat strain had 

been submitted to the FDA by the manufacturer, 

Wyeth Laboratories. Subsequently, because of the 

marked neoplastic responses found in the two mouse 

strains, the NTP initiated further 2-year studies of 

oxazepam with the F344/N rat. 

The current studies include measures of serum oxazepam concentrations and histopathologic evaluation of 

tissues from the 2-year animals. No 13-week studies 

were performed with oxazepam in rats because it was 

determined that the prior 13-week studies with mice 

gave very little information on which to base dose 

selection for the 2-year studies. For this reason, 

five exposure concentrations were chosen for the 

2-year evaluation. After 26 weeks, one exposure 

group considered uninformative was terminated, and 

the highest exposure group was removed from dosed 

feed for the duration of the study. A separate set of 

studies evaluating a number of biochemical changes in 

the F344/N rat following short-term exposure to oxazepam is summarized in Appendix H. 
21 

MATERIALS AND METHODS
 

PROCUREMENT AND 

CHARACTERIZATION OF OXAZEPAM 

Oxazepam was obtained from Roussel Corporation 

(Englewood Cliffs, NJ) in one lot (86017.01). Identity, purity, and stability analyses were conducted by 

the analytical chemistry laboratory, Midwest Research 

Institute (Kansas City, MO) (Appendix D). Reports 

on analyses performed in support of the oxazepam 

studies are on file at the NIEHS. 

The chemical, a white, powdered solid, was identified 

as oxazepam by infrared, ultraviolet/visible, and 

nuclear magnetic resonance spectroscopy. Purity of 

oxazepam was determined by elemental analyses, Karl 

Fischer water analysis, functional group titration, thinlayer chromatography (two systems), and highperformance liquid chromatography. Elemental 

analyses for carbon, hydrogen, nitrogen, and chlorine 

were in agreement with the theoretical values for 

oxazepam. Karl Fischer water analysis indicated 

0.026% ± 0.001% water. Functional group titration 

indicated a purity of 101.4% ± 0.5%. Thin-layer 

chromatography indicated a major spot and one trace 

impurity in one system, and only a major spot in a 

second system. High-performance liquid chromatography revealed a major peak with no impurity 

peaks with areas greater than 0.1% of the major peak 

area. The overall purity was determined to be greater 

than 99%. 

Stability studies of the bulk chemical were performed 

by the analytical chemistry laboratory using highperformance liquid chromatography. These studies 

indicated that oxazepam was stable as a bulk chemical 

for 2 weeks when stored protected from light at 

temperatures up to 60E C. To ensure stability, the 

bulk chemical was stored at room temperature, protected from light, in metal cans or amber glass bottles. 

Stability was monitored during the 2-year study using 

high-performance liquid chromatography. No degradation of the bulk chemical was detected. 

PREPARATION AND ANALYSIS 

OF DOSE FORMULATIONS 

The dose formulations were prepared every 2 weeks 

by mixing oxazepam with feed (Table D1). Homogeneity and stability studies of a 500 ppm dose 

formulation were performed by the analytical chemistry laboratory using high-performance liquid chromatography. Homogeneity was confirmed and the 

stability of the dose formulation was confirmed for at 

least 3 weeks at 5E C when stored protected from 

light. 

Periodic analyses of the dose formulations of oxazepam were conducted at the study laboratory 

and analytical chemistry laboratory using highperformance liquid chromatography. During the 

2-year study, dose formulations were analyzed every 

8 weeks (Table D2). All 50 of the dose formulations 

analyzed were within 10% of the target concentrations; 

89% (17/19) of the animal room samples analyzed 

were within 10% of the target concentrations with no 

value differing more than 12% from the target 

concentration. 

2-YEAR STUDY 

Study Design 

Groups of 50 male and 50 female F344/N rats were 

fed diets containing 0, 625, 1,250, 2,500, 5,000, or 

10,000 ppm oxazepam for up to 105 weeks. The 

exposure concentrations were selected to provide a 

wide exposure range. No 13-week rat studies were 

performed because the data from the 13-week mouse 

study did not provide useful information for the 

selection of exposure concentrations for the prior 

2-year mouse studies (NTP, 1993), and it was not 

anticipated that useful information would be gained 

from a 13-week rat study. The 5,000 ppm exposure 

concentration was determined during the course of the 

study to be the maximum tolerated dose. Concentrations of 0, 625, 2,500, and 5,000 ppm were 

selected for the continuous-exposure study. After 
22 Oxazepam, NTP TR 468 

26 weeks of exposure, rats in the 1,250 ppm group 

were eliminated from the study because it was anticipated that this group would provide no useful information. Rats in the 625, 2,500, and 5,000 ppm 

groups received dosed feed throughout the 2-year 

study. Rats in the 10,000 ppm group stopped 

receiving oxazepam in feed at 26 weeks and remained 

on control feed until study termination. 

Source and Specification of Animals 

Male and female F344/N rats were obtained from 

Taconic Farms (Germantown, NY) for use in the 

2-year study. Rats were quarantined for 13 days 

(males) or 14 days (females) before the beginning of 

the studies and were approximately 6 weeks old at the 

beginning of the study. Five male and five female rats 

were randomly selected for parasite evaluation and 

gross observation of disease at the end of the quarantine period. The health of the animals was 

monitored during the study according to the protocols 

of the NTP Sentinel Animal Program (Appendix G). 

Animal Maintenance 

Rats were housed five per cage. Feed and water were 

available ad libitum. Feed consumption was measured 

for a 7-day interval during weeks 1 and 4 and every 

4 weeks thereafter by cage. Cages were changed twice 

per week, and racks were rotated every 2 weeks. 

Further details of animal maintenance are given in 

Table 1. Information on feed composition and 

contaminants is provided in Appendix F. 

Clinical Examinations and Pathology 

All animals were observed twice daily. Clinical 

findings were recorded every 4 weeks and at study 

termination. Individual body weights were recorded 

weekly for 13 weeks, monthly thereafter, and at the 

end of the study. 

During study weeks 105 (males) and 104 (females) 

(1 to 3 days prior to necropsy), blood samples were 

collected from the retroorbital sinus of up to six males 

and six females in the 625, 2,500, and 5,000 ppm 

groups either at 6:00 a.m. or 6:00 p.m. On the days 

of necropsy, blood samples were similarly collected 

from up to 17 randomly selected female rats that had 

not been bled earlier. Plasma oxazepam concentrations were measured in all samples by Midwest 

Research Institute. 

A complete necropsy and microscopic examination 

were performed on all rats in the 0, 625, 2,500, and 

5,000 ppm groups. Rats in the 1,250 ppm group were 

discarded without tissue collection at 26 weeks. 

Histopathologic evaluation of rats in the 10,000 ppm 

group was limited to gross lesions, stomach (forestomach and glandular), small intestine, kidney, 

thyroid gland, and the liver. At necropsy, all organs 

and tissues were examined for grossly visible lesions, 

and all major tissues were fixed and preserved in 

10% neutral buffered formalin, processed and 

trimmed, embedded in paraffin, sectioned to a thickness of 5 to 6 μm, and stained with hematoxylin and 

eosin for microscopic examination. For extended 

evaluation of renal tubule proliferative lesions in male 

rats, kidneys were step-sectioned at 1-mm intervals to 

obtain a maximum of four additional sections per 

kidney. For all paired organs (i.e., adrenal gland, 

kidney, and ovary), samples from each organ were 

examined. Tissues examined microscopically are 

listed in Table 1. 

Microscopic evaluations were completed by the study 

laboratory pathologist, and the pathology data were 

entered into the Toxicology Data Management System. 

The slides, paraffin blocks, and residual wet tissues 

were sent to the NTP Archives for inventory, 

slide/block match, and wet tissue audit. The slides, 

individual animal data records, and pathology tables 

were evaluated by an independent quality assessment 

laboratory. The individual animal records and tables 

were compared for accuracy, the slide and tissue 

counts were verified, and the histotechnique was 

evaluated. For the 2-year study, a quality assessment 

pathologist evaluated slides from all tumors and all 

potential target organs, which included the adrenal 

cortex, forestomach, glandular stomach, and liver of 

males and females; the adrenal medulla, duodenum, 

eye, kidney, pancreas, preputial gland, rectum, and 

skin of males; and the spleen and thyroid gland of 

females. 

The quality assessment report and the reviewed slides 

were submitted to the NTP Pathology Working Group 

(PWG) chairperson, who reviewed the selected tissues 

and addressed any inconsistencies in the diagnoses 

made by the laboratory and quality assessment 
Oxazepam, NTP TR 468 23 

pathologists. Representative histopathology slides 

containing examples of lesions related to chemical 

administration, examples of disagreements in 

diagnoses between the laboratory and quality 

assessment pathologist, or lesions of general interest 

were presented by the chairperson to the PWG for 

review. The PWG consisted of the quality assessment 

pathologist and other pathologists experienced in 

rodent toxicologic pathology. This group examined 

the tissues without any knowledge of dose groups or 

previously rendered diagnoses. When the PWG 

consensus differed from the opinion of the laboratory 

pathologist, the diagnosis was changed. Final 

diagnoses for reviewed lesions represent a consensus 

between the laboratory pathologist, reviewing 

pathologist(s), and the PWG. Details of these review 

procedures have been described, in part, by Maronpot 

and Boorman (1982) and Boorman et al. (1985). For 

subsequent analyses of the pathology data, the decision 

of whether to evaluate the diagnosed lesions for each 

tissue type separately or combined was generally based 

on the guidelines of McConnell et al. (1986). 

STATISTICAL METHODS 

Survival Analyses 

The probability of survival was estimated by the 

product-limit procedure of Kaplan and Meier (1958) 

and is presented in the form of graphs. Animals found 

dead of other than natural causes were censored from 

the survival analyses; animals dying from natural 

causes were not censored. Statistical analyses for 

possible dose-related effects on survival used Cox’s 

(1972) method for testing two groups for equality and 

Tarone’s (1975) life table test to identify dose-related 

trends. All reported P values for the survival analyses 

are two sided. 

Calculation of Incidence 

The incidences of neoplasms or nonneoplastic lesions 

as presented in Tables A1, A5, B1, and B5 are given 

as the number of animals bearing such lesions at a 

specific anatomic site and the number of animals with 

that site examined microscopically. For calculation of 

statistical significance, the incidences of most neoplasms (Tables A3a, A3b, B3a, and B3b) and all 

nonneoplastic lesions are given as the numbers of 

animals affected at each site examined microscopically. 

However, when macroscopic examination was 

required to detect neoplasms in certain tissues (e.g., 

harderian gland, intestine, mammary gland, and skin) 

before microscopic evaluation, or when neoplasms had 

multiple potential sites of occurrence (e.g., leukemia 

or lymphoma), the denominators consist of the number 

of animals on which a necropsy was performed. 

Tables A3a, A3b, B3a, and B3b also give the survivaladjusted neoplasm rate for each group and each sitespecific neoplasm, i.e., the Kaplan-Meier estimate of 

the neoplasm incidence that would have been observed 

at the end of the study in the absence of mortality from 

all other competing risks (Kaplan and Meier, 1958). 

Analysis of Neoplasm Incidences 

The majority of neoplasms in these studies were 

considered to be incidental to the cause of death or not 

rapidly lethal. Thus, the primary statistical method 

used was logistic regression analysis, which assumed 

that the diagnosed neoplasms were discovered as the 

result of death from an unrelated cause and thus did 

not affect the risk of death. In this approach, neoplasm prevalence was modeled as a logistic function of 

chemical exposure and time. Both linear and quadratic 

terms in time were incorporated initially, and the 

quadratic term was eliminated if the fit of the model 

was not significantly enhanced. The neoplasm 

incidences of exposed and control groups were 

compared on the basis of the likelihood score test for 

the regression coefficient of dose. This method of 

adjusting for intercurrent mortality is the prevalence 

analysis of Dinse and Lagakos (1983), further 

described and illustrated by Dinse and Haseman 

(1986). When neoplasms are incidental, this comparison of the time-specific neoplasm prevalences also 

provides a comparison of the time-specific neoplasm 

incidences (McKnight and Crowley, 1984). 

In addition to logistic regression, other methods of 

statistical analysis were used, and the results of these 

tests are summarized in the appendixes. These methods include the life table test (Cox, 1972; Tarone, 

1975), appropriate for rapidly lethal neoplasms, and 

the Fisher exact test and the Cochran-Armitage trend 

test (Armitage, 1971; Gart et al., 1979), procedures 

based on the overall proportion of neoplasm-bearing 

animals. 

Tests of significance included pairwise comparisons of 

each exposed group with controls and a test for an 

overall dose-related trend. Continuity-corrected tests 

were used in the analysis of neoplasm incidence, and 

reported P values are one sided. The procedures 
24 Oxazepam, NTP TR 468 

described in the preceding paragraphs were also used 

to evaluate selected nonneoplastic lesions. For further 

discussion of these statistical methods, refer to 

Haseman (1984). 

Analysis of Nonneoplastic Lesion Incidences 

Because all nonneoplastic lesions in this study were 

considered to be incidental to the cause of death or not 

rapidly lethal, the primary statistical analysis used was 

a logistic regression analysis in which nonneoplastic 

lesion prevalence was modeled as a logistic function of 

chemical exposure and time. 

Analysis of Continuous Variables 

Prior to analysis, extreme values identified by the 

outlier test of Dixon and Massey (1951) were examined by NTP personnel, and implausible values were 

eliminated from the analysis. Average severity values 

were analyzed for significance using the MannWhitney U test (Hollander and Wolfe, 1973). 

Historical Control Data 

Although the concurrent control group is always the 

first and most appropriate control group used for 

evaluation, historical control data can be helpful in the 

overall assessment of neoplasm incidence in certain 

instances. Consequently, neoplasm incidences from 

the NTP historical control database, which is updated 

yearly, are included in the NTP reports for neoplasms 

appearing to show compound-related effects. 

QUALITY ASSURANCE METHODS 

The 2-year study was conducted in compliance with 

Food and Drug Administration Good Laboratory 

Practice Regulations (21 CFR, Part 58). In addition, 

as records from the 2-year study were submitted to the 

NTP Archives, this study was audited retrospectively 

by an independent quality assurance contractor. 

Separate audits covering completeness and accuracy of 

the pathology data, pathology specimens, final 

pathology tables, and a draft of this NTP Technical 

Report were conducted. Audit procedures and findings are presented in the reports and are on file at 

NIEHS. The audit findings were reviewed and 

assessed by NTP staff, so all comments had been 

resolved or were otherwise addressed during the 

preparation of this Technical Report. 

GENETIC TOXICOLOGY 

The genetic toxicity of oxazepam was assessed by 

testing the ability of the chemical to induce mutations 

in various strains of Salmonella typhimurium, sister 

chromatid exchanges and chromosomal aberrations in 

cultured Chinese hamster ovary cells, and increases in 

the frequency of micronucleated erythrocytes in 

peripheral blood of mice. The protocols for these 

studies and the results are given in Appendix C. 

The genetic toxicity studies of oxazepam are part of a 

larger effort by the NTP to develop a database that 

would permit the evaluation of carcinogenicity in 

experimental animals from the molecular structure and 

the effects of the chemical in short-term in vitro and 

in vivo genetic toxicity tests. These genetic toxicity 

tests were originally developed to study mechanisms of 

chemical-induced DNA damage and to predict 

carcinogenicity in animals, based on the electrophilicity theory of chemical mutagenesis and the 

somatic mutation theory of cancer (Miller and Miller, 

1977; Straus, 1981; Crawford, 1985). 

There is a strong correlation between a chemical’s 

potential electrophilicity (structural alert to DNA 

reactivity), mutagenicity in Salmonella, and carcinogenicity in rodents. The combination of electrophilicity and Salmonella mutagenicity is highly 

correlated with the induction of carcinogenicity in rats 

and mice and/or at multiple tissue sites (Ashby and 

Tennant, 1991). Other in vitro genetic toxicity tests 

correlate less well with rodent carcinogenicity 

(Tennant et al., 1987; Zeiger et al., 1990), although 

these other tests can provide information on the types 

of DNA and chromosome effects that can be induced 

by the chemical being investigated. Data from NTP 

studies show that a positive response in Salmonella is 

the most predictive in vitro test for rodent carcinogenicity (89% of the Salmonella mutagens are rodent 

carcinogens), and that there is no complementarity 

among the in vitro genetic toxicity tests. That is, no 

battery of tests that included the Salmonella test 

improved the predictivity of the Salmonella test alone. 

The predictivity for carcinogenicity of a positive 

response in bone marrow chromosome aberration or 

micronucleus tests appears to be less than the 

Salmonella test (Shelby et al., 1993; Shelby and Witt, 
Oxazepam, NTP TR 468 25 

1995). Positive responses in long term peripheral adverse effects in somatic and germ cells, the 

blood micronucleus tests have not been formally eval- determination of in vivo genetic effects is important to 

uated for their predictivity for rodent carcinogenicity. the overall understanding of the risks associated with 

But because of the theoretical and observed exposure to a particular chemical. 

associations between induced genetic damage and 
26 Oxazepam, NTP TR 468 

TABLE 1 

Experimental Design and Materials and Methods in the 2-Year Feed Study of Oxazepam 

Study Laboratory 

Battelle Columbus Laboratories (Columbus, OH) 

Strain and Species 

F344/N rats 

Animal Source 

Taconic Farms (Germantown, NY) 

Time Held Before Studies 

13 days (males) or 14 days (females) 

Average Age When Studies Began 

6 weeks 

Date of First Dose 

23 September (males) or 24 September (females) 1991 

Duration of Dosing 

1,250 and 10,000 ppm groups: 26 weeks 

0, 625, 2,500, and 5,000 ppm groups: 105 weeks 

Date of Last Dose 

1,250 and 10,000 ppm groups: 23 - 24 March 1992 

625, 2,500, and 5,000 ppm groups: 21 - 23 September 1993 

Necropsy Dates 

21 - 23 September 1993 

Average Age at Necropsy 

111 weeks 

Size of Study Groups 

50 males and 50 females 

Method of Animal Distribution 

Animals were distributed randomly into groups of approximately equal initial mean body weights. 

Animals per Cage 

5 

Method of Animal Identification 

Tail tattoo 

Diet 

NIH-07 Open Formula meal diet (Zeigler Brothers Inc., Gardners, PA), available ad libitum, changed weekly or as necessary 

Water Distribution 

Tap water (Columbus, OH, municipal supply) distributed via automatic watering system (Edstrom Industries Inc., Waterford, WI), available 

ad libitum 

Cages 

Polycarbonate (Lab Products Inc., Maywood, NJ), changed twice weekly 

Bedding 

Sani-Chips® heat-treated hardwood chips (P.J. Murphy Forest Products Corp., Montville, NJ), changed twice weekly 
Oxazepam, NTP TR 468 27 

TABLE 1
 

Experimental Design and Materials and Methods in the 2-Year Feed Study of Oxazepam (continued)
 

Cage Filters 

DuPont 2024 spun-bonded polyester filters (Snow Filtration Co., Cincinnati, OH), changed once every 2 weeks 

Racks 

Stainless steel (Lab Products Inc., Maywood, NJ), rotated every 2 weeks 

Animal Room Environment 

Temperature: 19.4E to 25.6E C 

Relative humidity: 36% to 66% 

Fluorescent light: 12 hours/day 

Room air: minimum of 10 changes/hour 

Doses 

0, 625, 1,250, 2,500, 5,000, or 10,000 ppm in feed 

Type and Frequency of Observation 

Rats were observed twice daily; clinical findings were recorded every 4 weeks and at study termination; individual body weights were 

recorded weekly for 13 weeks, monthly thereafter, and at study termination. Feed consumption was recorded for a 7-day interval during 

study weeks 1 and 4, and every 4 weeks thereafter by cage. 

Method of Sacrifice 

CO2 asphyxiation 

Necropsy 

Necropsy performed on all rats except the 1,250 ppm group 

Histopathology 

Complete histopathology was performed on all 0, 625, 2,500, and 5,000 ppm rats. In addition to gross lesions, tissue masses, and associated 

lymph nodes, the tissues examined included: adrenal gland, brain, clitoral gland, esophagus, eyes, heart, large intestine (cecum, colon, and 

rectum), small intestine (duodenum, jejunum, and ileum), kidney, liver, lung, lymph nodes (mandibular and mesenteric), mammary gland, 

nose, ovary, pancreas, parathyroid gland, pituitary gland, preputial gland, prostate gland, salivary gland, skin, spleen, stomach (forestomach 

and glandular stomach), testis, thymus, thyroid gland, trachea, urinary bladder, and uterus. Histopathologic evaluation was limited to gross 

lesions, stomach (forestomach and glandular), small intestine, kidney, thyroid gland, and liver for the 10,000 ppm group. 

Plasma Oxazepam Determinations 

At weeks 27 (1,250 ppm group) and 105 (males) and 104 (females) (625, 2,500, and 5,000 ppm groups), blood was collected from the vena 

cava or retroorbital sinus for plasma oxazepam assays. 
28 Oxazepam, NTP TR 468
 
29 

RESULTS
 

2-YEAR STUDY 

Survival 

Estimates of 2-year survival probabilities for male and Survival of 2,500 ppm continuous-exposure males 

female rats are shown in Table 2 and in the and females was significantly less than that of the 

Kaplan-Meier survival curves (Figures 3 and 4). All controls. However, survival of 5,000 ppm females 

5,000 ppm continuous-exposure and 10,000 ppm stop- did not differ from that of the controls. 

exposure males died before the end of the study. 

TABLE 2 

Survival of Rats in the 2-Year Feed Study of Oxazepam 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Male 

Animals initially in study 50 50 50 50 50 

Moribund 25 27 33 43 39 

Natural deaths 8 12 11 7 11 

Animals surviving to study termination 17 11 6 0 0 

Percent probability of survival at end a of study 34 22 12 0 0 

Mean survival (days)b 662 616 621 531 617 

c Survival analysis P<0.001 P=0.070 P=0.002 P<0.001 P<0.001 

Female 

Animals initially in study 50 50 50 50 50 

d Accidental death 1 0 0 0 0 

Moribund 11 18 18 16 19 

Natural deaths 6 6 12 3 6 

Animals surviving to study termination 32 26 20 31 25 

Percent probability of survival at end

 of study 66 52 40 62 50 

Mean survival (days) 676 679 655 686 685 

Survival analysis	 P=1.000 P=0.339 P=0.019 P=0.967 P=0.257 

a Kaplan-Meier determinations b	 Mean of all deaths (uncensored, censored, and terminal sacrifice) 

The result of the life table trend test (Tarone, 1975) is in the control column (the 10,000 ppm stop-exposure group was excluded from the 

trend test), and the results of the life table pairwise comparisons (Cox, 1972) with the controls are in the exposed group columns. d	 Censored from survival analyses 

c 
 

30 Oxazepam, NTP TR 468 

FIGURE 3
 

Kaplan-Meier Survival Curves for Male and Female Rats
 

Administered Oxazepam in Feed for 2 Years
 
 

Oxazepam, NTP TR 468 31 

FIGURE 4
 

Kaplan-Meier Survival Curves for Male and Female Rats
 

in the 2 Year Stop-Exposure Feed Study of Oxazepam
 
32 Oxazepam, NTP TR 468 

Body Weights, Feed and Compound 

Consumption, and Clinical Findings 

The mean body weight gains of 2,500 and 5,000 ppm 

males and females were less than those of the controls 

throughout the study (Figure 5, Tables 3 and 4). The 

final mean body weights were 74% (2,500 ppm 

males), 62% (5,000 ppm males), 85% (2,500 ppm 

females), and 82% (5,000 ppm females) that of the 

respective controls. The mean body weights of 

10,000 ppm stop-exposure males were generally less 

than those of the controls throughout the study 

(Figure 6). The mean body weight of 10,000 ppm 

stop-exposure females was approximately 18% less 

than that of the controls at week 29, but increased 

steadily after the cessation of dosing at week 27, and 

was similar to that of the controls at the end of the 

study. 

During the first week of the study, there was a slight 

exposure concentration-related decrease in the amount 

of feed consumed by exposed rats compared to that by 

the controls (Tables E1 and E2). The reduction in 

feed consumption was not apparent after the first week 

of the study, and the reduced consumption was 

attributed to the initial ataxia experienced during the 

first week of the study rather than to poor palatability 

of the dosed feed. At the end of the study, the average 

daily feed consumption by exposed male and female 

rats was similar to that by the controls. In 

10,000 ppm stop-exposure males and females, the feed 

consumption was also similar to that by the controls. 

Dietary levels of 625, 2,500, 5,000, and 10,000 ppm 

delivered average daily doses of 25, 100, 250, and 

630 mg oxazepam/kg body weight to males and 25, 

110, 220, and 630 mg/kg to females. Treatmentrelated eye/nasal discharge, hyperactivity when 

handled, and/or ataxia were observed in exposed 

males and females on or about day 2 of exposure but 

were no longer apparent after day 7. The duration and 

severity of ataxia were exposure-concentration 

dependent. On day 2, ataxia was slight in male and 

female rats exposed to 625 or 1,250 ppm, moderate in 

male and female rats exposed to 2,500 ppm and female 

rats exposed to 5,000 ppm, and severe in male rats 

exposed to 5,000 ppm and male and female rats 

exposed to 10,000 ppm. 

The severity of ataxia diminished daily and was not 

apparent after day 2 in rats exposed to 625 ppm or 

2,500 ppm or after days 3 (males) or 6 (females) in 

rats exposed to 5,000 ppm. Hyperactivity and 

eye/nasal discharge were observed in male and female 

rats exposed to 5,000 ppm but were not apparent after 

days 3 (males) or 6 (females) of exposure. Male and 

female stop-exposure rats were hyperactive on day 197 

after being switched to undosed feed. 
 

Oxazepam, NTP TR 468 33 

FIGURE 5
 

Growth Curves for Male and Female Rats
 

Administered Oxazepam in Feed for 2 Years
 
34 Oxazepam, NTP TR 468 

TABLE 3 

Mean Body Weights and Survival of Male Rats in the 2-Year Feed Study of Oxazepam 

Weeks 0 ppm 625 ppm 2,500 ppm 

on Av. Wt. No. of Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of 

Study (g) Survivors (g) controls) Survivors (g) controls) Survivors 

1 132 50 132 100 50 132 100 50 

2 172 50 179 104 50 174 101 50 

3 211 50 218 103 50 216 102 50 

4 240 50 246 103 50 242 101 50 

5 257 50 265 103 50 262 102 50 

6 278 50 286 103 50 283 102 50 

7 297 50 304 102 50 296 99 50 

8 310 50 315 102 50 306 99 50 

9 323 50 326 101 50 314 97 50 

10 331 50 336 102 50 323 98 50 

11 344 50 347 101 50 332 97 50 

12 356 50 354 99 50 343 96 50 

13 367 50 366 100 50 349 95 50 

17 402 50 391 97 50 375 93 50 

21 422 50 413 98 50 393 93 50 

25 442 50 434 98 50 408 92 50 

29 462 50 448 97 50 426 92 50 

33 477 50 459 96 50 437 92 50 

37 479 50 465 97 50 438 92 50 

41 487 50 471 97 50 443 91 50 

45 492 50 479 97 50 451 92 50 

49 497 50 485 98 50 454 91 50 

53 503 50 492 98 50 449 89 50 

57 509 50 496 97 49 451 89 49 

61 509 50 488 96 49 449 88 47 

65 504 50 486 96 47 445 88 45 

69 506 49 492 97 44 443 88 45 

73 508 46 487 96 42 434 86 44 

77 500 44 478 96 40 432 86 42 

78 500 43 476 95 38 431 86 42 

81 493 41 471 96 36 414 84 40 

85 495 39 463 94 28 407 82 36 

88 493 36 452 92 27 396 80 32 

93 489 35 449 92 21 397 81 25 

97 470 35 441 94 18 372 79 17 

101 459 20 429 94 16 349 76 9 

104 463 17 428 93 11 341 74 6 

Mean for weeks 

1-13 278 283 102 275 99 

14-52 462 449 97 425 92 

53-104 493 469 95 414 84 
Oxazepam, NTP TR 468 35 

TABLE 3
 

Mean Body Weights and Survival of Male Rats in the 2-Year Feed Study of Oxazepam (continued)
 

Weeks 5,000 ppm 10,000 ppma 

on Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of 

Study (g) controls) Survivors (g) controls) Survivors 

1 132 100 50 132 99 50 

2 168 98 50 164 96 50 

3 213 101 50 208 99 50 

4 238 100 50 232 97 50 

5 254 99 50 247 96 50 

6 270 97 50 263 95 50 

7 284 95 50 275 93 50 

8 294 95 50 284 92 50 

9 304 94 50 290 90 50 

10 318 96 50 303 92 50 

11 324 94 50 309 90 50 

12 331 93 50 322 91 50 

13 338 92 50 323 88 50 

17 355 88 50 344 86 50 

21 375 89 50 358 85 50 

25 386 87 50 366 83 50 

29 400 87 50 361 78 50 

33 401 84 48 404 85 50 

37 401 84 47 424 89 50 

41 411 84 47 437 90 50 

45 420 85 47 449 91 50 

49 421 85 47 462 93 49 

53 420 84 47 467 93 49 

57 417 82 47 472 93 49 

61 403 79 47 473 93 49 

65 396 79 42 469 93 49 

69 388 77 38 469 93 49 

73 363 72 36 474 93 45 

77 358 72 24 469 94 45 

78 351 70 24 469 94 45 

81 334 68 20 458 93 43 

85 328 66 13 445 90 37 

88 313 63 10 425 86 31 

93 314 64 5 427 87 17 

97 333 71 4 403 86 12 

101 285 62 3 

Mean for weeks 

1-13 267 96 258 94 

14-52 397 86 401 87 

53-101 357 72 455 91 

a Stop-exposure group 
36 Oxazepam, NTP TR 468 

TABLE 4 

Mean Body Weights and Survival of Female Rats in the 2-Year Feed Study of Oxazepam 

Weeks 0 ppm 625 ppm 2,500 ppm 

on Av. Wt. No. of Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of 

Study (g) Survivors (g) controls) Survivors (g) controls) Survivors 

1 111 50 111 100 50 111 100 50 

2 129 50 132 103 50 133 103 50 

3 142 50 149 105 50 148 104 50 

4 153 50 159 104 50 157 103 50 

5 162 50 167 103 50 165 102 50 

6 171 50 177 103 50 172 100 50 

7 178 50 181 102 50 177 100 50 

8 182 50 185 102 50 180 99 50 

9 187 50 188 101 50 182 98 50 

10 191 50 193 101 50 186 97 50 

11 195 50 198 101 50 190 97 50 

12 200 50 200 101 50 194 97 50 

13 203 50 206 101 50 197 97 50 

17 216 50 218 101 50 207 96 50 

21 223 50 226 101 50 216 97 50 

25 234 50 235 100 50 224 96 50 

29 241 50 245 102 50 232 96 50 

33 247 49 253 102 50 238 96 50 

37 255 48 258 101 50 243 95 50 

41 263 48 270 103 50 249 95 50 

45 273 48 280 103 49 259 95 50 

49 286 48 289 101 49 264 92 50 

53 298 48 301 101 49 272 91 50 

57 308 48 311 101 49 277 90 50 

61 315 48 318 101 48 284 90 49 

65 322 48 323 100 48 296 92 48 

69 328 48 328 100 47 303 93 47 

73 328 48 330 101 46 302 92 47 

77 328 46 333 101 46 304 93 46 

81 333 45 341 102 45 308 92 42 

85 339 42 339 100 45 316 93 37 

88 343 40 343 100 42 316 92 34 

93 343 39 344 100 39 317 92 31 

97 343 38 348 101 35 314 91 28 

101 348 34 345 99 34 314 90 23 

104 348 32 343 98 27 296 85 21 

Mean for weeks 

1-13 170 173 102 169 100 

14-52 249 253 102 237 95 

53-104 330 332 100 301 91 
Oxazepam, NTP TR 468 37 

TABLE 4
 

Mean Body Weights and Survival of Female Rats in the 2-Year Feed Study of Oxazepam (continued)
 

Weeks 5,000 ppm 10,000 ppma 

on Av. Wt. Wt. (% of No. of Av. Wt. Wt. (% of No. of 

Study (g) controls) Survivors (g) controls) Survivors 

1 111 100 50 111 99 50 

2 134 104 50 133 103 50 

3 150 105 50 147 104 50 

4 158 103 49 156 102 50 

5 164 101 49 162 100 50 

6 170 99 49 168 98 50 

7 174 98 49 173 97 50 

8 177 97 49 175 96 50 

9 182 97 49 177 95 50 

10 184 96 49 183 96 50 

11 187 96 49 185 95 50 

12 191 96 49 187 94 50 

13 192 94 49 188 93 50 

17 203 94 49 197 91 50 

21 208 93 49 202 91 50 

25 216 92 49 208 89 50 

29 225 94 49 198 82 50 

33 229 93 49 224 90 50 

37 235 92 49 235 92 50 

41 241 92 49 245 93 50 

45 251 92 49 255 94 50 

49 251 88 49 266 93 50 

53 256 86 49 277 93 50 

57 261 85 49 290 94 50 

61 265 84 48 304 96 50 

65 270 84 48 316 98 50 

69 278 85 48 323 99 50 

73 277 84 48 324 99 49 

77 285 87 48 330 101 48 

81 283 85 47 331 100 48 

85 288 85 47 336 99 43 

88 287 84 47 346 101 39 

93 282 82 41 352 102 39 

97 282 82 39 357 104 35 

101 285 82 35 356 103 33 

104 284 82 31 346 100 27 

Mean for weeks 

1-13 167 99 165 98 

14-52 229 92 226 91 

53-104 277 84 328 99 

a Stop-exposure group 
 

38 Oxazepam, NTP TR 468 

FIGURE 6
 

Growth Curves for Male and Female Rats in the
 

2 Year Stop-Exposure Feed Study of Oxazepam
 
Oxazepam, NTP TR 468 39 

Plasma Oxazepam Determinations 

Plasma oxazepam concentrations were measured at the exposure concentration (Table 5). The concentrations 

end of the study. Due to mortality, no blood samples were somewhat higher than reported serum concenfrom males exposed to 5,000 ppm were available at trations in humans (0.3 to 1 μg/mL) receiving a therathe end of the study. Plasma oxazepam concentrations peutic dose of oxazepam (Greenblatt et al., 1980; 

were similar between males and females at each Salzman et al., 1983). 

TABLE 5 

Plasma Concentrations of Oxazepam in Rats in the 2-Year Feed Study of Oxazepama 

625 ppm 2,500 ppm 5,000 ppm 

Male 

n 10 6 Ób 

Week 105 0.50 ± 0.04 1.94 ± 0.34 Ó 

Female 

n 25 19 28 

Weeks 104-105 0.60 ± 0.05 1.61 ± 0.16 2.79 ± 0.24 

a Mean ± standard error; values given as Fg/mL b No samples collected due to 100% mortality 

Pathology and Statistical Analyses 

This section describes the statistically significant or 

biologically noteworthy changes in the incidences of 

neoplasms and/or nonneoplastic lesions of the kidney 

(with parathyroid gland and bone), gastrointestinal 

tract (forestomach, glandular stomach, and small 

intestine), liver, mammary gland, adrenal medulla, 

pituitary gland, and pancreas. Summaries of the 

incidences of neoplasms and nonneoplastic lesions, 

individual animal tumor diagnoses, statistical analyses 

of primary neoplasms that occurred with an incidence 

of at least 5% in at least one animal group, and 

historical incidences for the neoplasms mentioned in 

this section are presented in Appendix A for male rats 

and Appendix B for female rats. 

Kidney (with parathyroid gland and bone): At histopathologic examination of the standard kidney sections, three renal tubule adenomas were seen in male 

rats exposed to 2,500 ppm, which was at the upper 

limit of the historical range for this neoplasm in 2-year 

NTP feed studies (Tables 6, A3a, and A4a). 

This increased incidence of renal tubule adenoma in 

male rats exposed to 2,500 ppm suggested a 

compound-related effect; therefore, an extended stepsection evaluation of the kidneys was performed (male 

rats only, exposed and control groups) using the 

remaining residual formalin-fixed kidney wet tissue. 

Additional rats with renal tubule adenoma and numerous additional incidences of renal epithelial hyperplasia were identified. The incidences of these 

proliferative lesions observed in the extended stepsection evaluation and the combined incidences of 

standard and step sections in male rats are presented in 

Tables 6, A3a, and A3b. The incidences of renal 

tubule adenomas in the extended evaluation and the 
40 Oxazepam, NTP TR 468 

TABLE 6 

Incidences of Neoplasms and Nonneoplastic Lesions of the Kidney of Rats in the 2-Year Feed Study 

of Oxazepam 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Male 

Single Sections (Standard Evaluation) 

Number Examined Microscopically 

Nephropathya 50 

49 (1.9)b 

50 

44 (2.3) 

50 

49 (2.7)** 

50 

50 (3.2)** 

42 

42 (3.3)** 

Renal Tubule Hyperplasia 0 1 (1.0) 3 (2.3) 1 (2.0) 0 

Renal Tubule Adenomac 

Overall rated 

Adjusted ratee 

Terminal ratef 

First incidence (days) 

Logistic regression testg 

1/50 (2%) 

5.6% 

0/17 (0%) 

723 

P=0.103 

0/50 (0%) 

0.0% 

0/11 (0%) 

— h 

P=0.588N 

3/50 (6%) 

23.8% 

1/6 (17%) 

641 

P=0.188 

1/50 (2%) 

16.7% 

0/0 

634 

P=0.503 

0/50 (0%) 

0.0% 

0/0 

— 

P=0.588N 

Step Sections (Extended Evaluation) 

Number Examined Microscopically 50 50 50 50 50 

Renal Tubule Hyperplasia 5 6 9 8 21** 

Renal Tubule Hyperplasia,

 Oncocytic 0 1 2 2 3 

Renal Tubule Adenoma, Multiple 0 1 1 1 1 

Renal Tubule Adenoma (includes multiple) 

Overall rate 1/50 (2%) 1/50 (2%) 4/50 (8%) 5/50 (10%) 6/45 (13%) 

Adjusted rate 5.9% 9.1% 31.3% 19.5% 31.9% 

Terminal rate 1/17 (6%) 1/11 (9%) 1/6 (17%) 0/0 0/0 

First incidence (days) 730 (T) 730 (T) 653 467 613 

Logistic regression test P=0.006 P=0.663 P=0.071 P=0.151 P=0.024 

Renal Tubule, Oncocytoma 0 0 0 1 0 

Single Sections and Step Sections (Combined) 

Number Examined Microscopically 50 50 50 50 45 

Renal Tubule Hyperplasia 5 6 12* 9* 21** 

Renal Tubule Hyperplasia,

 Oncocytic 0 1 2 2 3i 

Renal Tubule Adenoma, Multiple 0 1 2 1 1 

Renal Tubule Adenoma (includes multiple) 

Overall rate 2/50 (4%) 1/50 (2%) 7/50 (14%) 6/50 (12%) 6/45 (13%) 

Adjusted rate 11.1% 9.1% 49.7% 32.9% 39.1% 

Terminal rate 1/17 (6%) 1/11 (9%) 2/6 (33%) 0/0 0/0 

First Incidence (days) 723 730 (T) 641 467 613 

Logistic regression test P=0.018 P=0.647 P=0.018 P=0.109 P=0.046 

Renal Tubule, Oncocytoma 0 0 0 1 0 
Oxazepam, NTP TR 468 41 

TABLE 6 

Incidences of Neoplasms and Nonneoplastic Lesions of the Kidney of Rats in the 2-Year Feed Study 

of Oxazepam (continued) 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Female 

Number Examined Microscopically 50 50 50 50 1j 

Nephropathy 32 (1.1) 43** (1.3) 41** (1.3) 48** (1.7)** 1 (2.0) 

* Significantly different (P#0.05) from the control group by the logistic regression test (incidence) or by the Mann-Whitney U test (severity) 

** P#0.01 a Number of animals with lesion 

b Average severity of lesions in affected animals: 1=minimal, 2=mild, 3=moderate, 4=marked c Historical incidence for 2-year NTP feed studies with untreated control groups (mean ± standard deviation): 9/1,301 (0.7% ± 1.5%); 

range, 0%-6% d	 Number of animals with neoplasms per number of animals with kidney examined microscopically e Kaplan-Meier estimated neoplasm incidence at the end of the study after adjustment for intercurrent mortality f	 Observed incidence in animals surviving until the end of the study g	 In the control column are the P values associated with the trend test (the 10,000 ppm stop-exposure group was excluded from the trend 

test). In the exposure group columns are the P values corresponding to pairwise comparisons between the controls and that exposure 

group. The logistic regression test regards lesions in animals dying prior to terminal kill as nonfatal. A lower incidence in an exposed 

group is indicated by N. h	 Not applicable; no neoplasms in animal group i	 Number examined microscopically equals 42. j Tissue was examined microscopically only when it was observed to be abnormal at necropsy; thus, statistical comparisons with the controls 

are not appropriate. 

combined incidences in standard and step sections 

were increased in 2,500, 5,000, and 10,000 ppm 

(stop-exposure) groups and were significantly greater 

in male rats in the 10,000 ppm (stop-exposure) group 

than in the controls. The incidences of renal tubule 

adenomas in the extended evaluation and the combined 

incidences in standard and step sections in these 

groups increased with a positive trend (Tables 6, A3a, 

A3b, and A4b). The incidences of renal tubule 

hyperplasia in standard and step sections (combined) 

in the male rats exposed to 2,500, 5,000, or 

10,000 ppm (stop-exposure) were significantly greater 

than that in the controls. 

One adenoma in each of the control and 2,500 and 

5,000 ppm groups was a grossly visible lesion at 

necropsy. Microscopically, approximately 50% of the 

adenomas in exposed groups in standard and step 

sections were approximately 1 mm in diameter. All 

were discrete, well-circumscribed lesions, five or more 

tubule diameters in size, and were distinguished from 

hyperplasia by having a more complex structure 

(Plates 1 and 2). 

Most hyperplasias were generally minimal to mild 

focal lesions consisting of tubules that were enlarged 

up to two to three times that of a normal tubule and 

were lined by increased numbers of epithelial cells 

which partially or totally filled the tubule lumen 

(Plates 3 and 4). Hyperplasia was considered a 

preneoplastic lesion and was distinguished from 

regenerative epithelial changes commonly seen as a 

component of chronic nephropathy. 

The incidences of nephropathy in the continuously 

exposed and stop-exposure male rats were similar to 

that in the controls (Tables 6 and A5). However, 

there was an exposure concentration-related increase 

in the severity (exacerbation) of nephropathy; the 

severities of nephropathy in male rats exposed to 

2,500, 5,000, or 10,000 ppm (stop-exposure) were 

significantly greater than that in the controls. The 

incidences of nephropathy in continuously exposed 
42 Oxazepam, NTP TR 468 

female rats were significantly greater than that in the males were significantly greater than those in the 

controls; however, the severity was significantly controls (Tables 7 and A5). In male rats exposed to 

increased only in the 5,000 ppm group (Tables 6 5,000 ppm, the incidences of mineralization of the 

and B5). Nephropathy in male rats was generally mild glandular stomach and erosion of the duodenum were 

in the control and 625 ppm groups and moderate to significantly greater than those in the controls. In the 

marked in the 2,500, 5,000, and 10,000 ppm (stop- 10,000 ppm stop-exposure males, the incidence of 

exposure) groups. Mild nephropathy involved less mineralization of the glandular stomach was signifithan 50% of the kidney and was composed of multi- cantly greater than that in the controls. In female rats 

focal renal tubule regeneration, minimal to mild tubule exposed to 2,500 ppm, the incidences of epithelial 

dilatation, and interstitial fibrosis with mononuclear hyperplasia, chronic inflammation, and ulcers in the 

infiltrates (Plate 5). Moderate nephropathy involved forestomach and of erosion of the glandular stomach 

a greater proportion of the kidney and consisted of a were significantly greater than those in the controls 

spectrum of changes that included dilatation of renal (Tables 7 and B5). 

tubules with hyaline or cellular casts, increased 

interstitial fibrosis with mononuclear inflammatory cell Epithelial hyperplasia of the forestomach occurred as 

infiltrates, and multifocal tubule regeneration. Severe focal or multifocal lesions of varying severity. Most 

nephropathy involved most of the kidney and consisted lesions occurred as slightly to moderately raised 

of a similar spectrum of lesions of greater severity thickenings of the mucosa, due to an increase in the 

(Plate 6). In addition, there was marked thickening number of epithelial cells at all levels of the epithelium 

and mineralization of the basement membrane of (Plates 7 and 8). Others were focal broad-based 

tubules, blood vessels, and glomeruli; atrophy of the lesions in which the epithelium was markedly thickglomerular tuft; dilatation of the glomerular urinary ened and thrown into papillary folds (Plates 9 and 10). 

space; and transitional epithelial hyperplasia of the In some cases, focal nests or finger-like projections of 

renal papilla. proliferative basal epithelium extended into the 

submucosa. Forestomach ulcers were also focal or 

Parathyroid gland hyperplasia and fibrous osteo- multifocal lesions characterized by loss of the mucosal 

dystrophy of the bone were considered secondary to squamous epithelium with necrosis and inflammation 

the exacerbated nephropathy that occurred in exposed of the adjacent muscularis mucosa and superficial 

male rats. In male rats, the incidences of parathyroid submucosa, with or without accompanying fibrosis 

gland hyperplasia (0 ppm, 3/39; 625 ppm, 6/41; (Plates 11 and 12). Variable thickening (hyperplasia) 

2,500 ppm, 9/46; 5,000 ppm, 16/40) and fibrous of the epithelium and keratin layer (hyperkeratosis) at 

osteodystrophy of the bone (0/50, 1/50, 6/50, 8/50) the edges of ulcers were consistent and frequently 

occurred with positive trends (Table A5). The inci- striking components of ulcerative lesions. Ulcers 

dences of parathyroid gland hyperplasia in male rats were sometimes accompanied by focal erosion of the 

exposed to 5,000 ppm and fibrous osteodystrophy of mucosal epithelium. Chronic active inflammation of 

the bone in male rats exposed to 2,500 or 5,000 ppm varying severity almost invariably occurred in the 

were greater than those in the controls. submucosa beneath hyperplastic and ulcerative lesions 

and consisted of a combination of edema and infiltrates 

Gastrointestinal Tract (forestomach, glandular stom- of neutrophils, macrophages, and lymphocytes with 

ach, and small intestine): In male rats, there were occasional focal hemorrhage (Plates 8, 10, and 12). In 

positive trends in the incidences of epithelial hyper- male rats, the incidence of mucosal erosions in the 

plasia and chronic inflammation of the forestomach. duodenum in the 5,000 ppm group was significantly 

The incidences of epithelial hyperplasia and chronic greater than in the controls. Erosions of the duodenum 

inflammation of the forestomach of males exposed to were characterized by focal loss and necrosis of the 

2,500 or 5,000 ppm and of ulcers in 2,500 ppm superficial mucosal epithelium. 
43 

c 

Oxazepam, NTP TR 468 

TABLE 7 

Incidences of Selected Nonneoplastic Lesions of the Gastrointestinal Tract of Rats in the 2-Year Feed Study of 

Oxazepam 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Male 

Forestomacha 

Chronic Inflammationb 

Ulcer 

Epithelium, Hyperplasia 

50 

6 

9 

5 

(1.5)c 

(2.7) 

(2.2) 

48 

8 

12 

8 

(1.5) 

(2.9) 

(2.0) 

50 

23** (2.0) 

20* (2.8) 

25** (2.3) 

50 

15* (1.9) 

10 (3.0) 

16** (2.4) 

49 

10 (2.2) 

7 (3.1) 

15* (2.5) 

Glandular Stomach 

Erosion 

Mineralization 

Ulcer 

50 

5 

0 

2 

(2.2) 

(2.5) 

48 

5 

3 

7 

(1.4) 

(2.3) 

(2.0) 

50 

9 

1 

7 

(2.3) 

(1.0) 

(1.6) 

50 

4 

4* 

4 

(2.5) 

(2.0) 

(1.8) 

47 

5 (1.4) 

16** (2.8) 

4 (2.8) 

Small Intestine, Duodenum 

Erosion 

50 

4 (2.0) 

48 

3 (2.3) 

49 

9 (1.8) 

50 

16* (2.4) 

44 

1 (1.0) 

Female 

Forestomach 

Chronic Inflammation 

Ulcer 

Epithelium, Hyperplasia 

50 

1 

1 

2 

(2.0) 

(3.0) 

(3.0) 

50 

5 

2 

6 

(1.8) 

(2.5) 

(2.2) 

50 

16** (2.0) 

9* (2.1) 

16** (2.3) 

50 

3 

6 

5 

(1.7) 

(2.2) 

(2.2) 

50 

5 

4 

5 

(1.4) 

(3.3) 

(1.8) 

Glandular stomach 

Erosion 

Ulcer 

Mineralization 

50 

0 

2 

1 

(2.0) 

(1.0) 

50 

4 

3 

0 

(2.0) 

(1.7) 

50 

7** (2.3) 

5 (2.0) 

1 (2.0) 

50 

2 

0 

2 

(2.0) 

(1.5) 

49 

0 

4 

0 

(2.0) 

* Significantly different (P#0.05) from the control group by the logistic regression test 

** P#0.01 a Number examined microscopically b Number of animals with lesion
 

Average severity of lesions in affected animals: 1=minimal, 2=mild, 3=moderate, 4=marked
 

Liver: The incidences of minimal to mild centrilobular females, 5,000 ppm continuous-exposure females, and 

hepatocyte hypertrophy in 2,500 and 5,000 ppm males 10,000 ppm stop-exposure females were significantly 

and females were significantly greater than those in less than in the controls. Centrilobular hypertrophy 

the controls (Tables 8, A5, and B5). In continuous- was characterized by enlargement of hepatocytes 

exposure females, the incidences of clear cell foci in around central veins; affected hepatocytes had more 

the 2,500 and 5,000 ppm groups were significantly abundant and more eosinophilic cytoplasm and slightly 

greater than in the controls but not in the 10,000 ppm larger nuclei than the surrounding unaffected 

stop-exposure group. The incidences of basophilic hepatocytes. 

foci in 2,500 ppm continuous-exposure males and 
44 Oxazepam, NTP TR 468 

TABLE 8 

Incidences of Nonneoplastic Lesions of the Liver of Rats in the 2-Year Feed Study of Oxazepam 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Male 

Number Examined Microscopically 

Basophilic Focusa 

Clear Cell Focus 

Eosinophilic Focus 

Mixed Cell Focus 

Hepatocyte, Centrilobular,

 Hypertrophy 

50 

21 

2 

8 

2 

0 

50 

11 

4 

5 

4 

1 (1.0) 

49 

4** (2.0) b 

0 

5 

2 

8** (1.0) 

50 

2 

0 

6 

1 

14** (1.3) 

50 

13 

0 

2 

1 

0 

Female 

Number Examined Microscopically 

Basophilic Focus 

Clear Cell Focus 

Eosinophilic Focus 

Mixed Cell Focus 

Hepatocyte, Centrilobular,

 Hypertrophy 

50 

44 

6 

17 

5 

0 

50 

41 

3 

18 

15* 

0 

50 

28** 

11* 

4** 

7 

10** (1.2) 

50 

26** 

22** 

11 

3 

31** (1.5) 

49 

16** 

0 

11 

2 

0 

* Significantly different (P#0.05) from the control group by the logistic regression test 

** P#0.01 a Number of animals with lesion 

b Average severity of lesions in affected animals: 1=minimal, 2=mild, 3=moderate, 4=marked 

Mammary Gland: In females exposed to 2,500 and pheochromocytoma of the adrenal medulla (0 ppm, 

5,000 ppm, the incidences of fibroadenoma were 14/50; 625 ppm, 9/50; 2,500 ppm, 6/50; 5,000 ppm, 

significantly less than that in the controls (Tables 9 3/50; Table A1), and the incidences in the 2,500 and 

and B3). The incidences of fibroadenoma; carcinoma; 5,000 ppm males were significantly less than that in 

and fibroadenoma, adenoma, or carcinoma (combined) the controls. The incidence of benign pheochromooccurred with negative trends. All neoplasm cytoma in 5,000 ppm male rats was less than the 

incidences were within the historical control ranges historical control range from 2-year NTP feed studies 

from NTP 2-year feed studies (Table B4). The (Table A4b). Adrenal glands were not routinely 

decreased incidences in 2,500 and 5,000 ppm females examined in the 10,000 ppm stop-exposure group. 

were most likely due to the significant reductions in The incidence of adrenal medulla hyperplasia in males 

mean body weights observed at these exposure exposed to 5,000 ppm was significantly (P#0.05) 

concentrations. The incidences of mammary gland greater than that in the controls (9/50, 9/50, 15/50, 

neoplasms in stop-exposure females were similar to 16/50; Table A5); the severities of this lesion in 

those in the controls. exposed rats were similar to that in the controls. This 

shift in the pattern of proliferative lesions of the 

adrenal medulla may be a consequence of the earlier 

Adrenal Medulla: In continuous-exposure males, there mortality in the 2,500 and 5,000 ppm and 10,000 ppm 

was a negative trend in the incidences of benign stop-exposure groups. 
Oxazepam, NTP TR 468 45 

TABLE 9 

Incidences of Mammary Gland Neoplasms in Female Rats in the 2-Year Study of Oxazepam

 0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Fibroadenomaa 

Overall rateb 25/50 (50%) 19/50 (38%) 9/50 (18%) 13/50 (26%) 23/50 (46%) c Adjusted rate 67.0% 52.8% 33.2% 35.1% 66.7% 

Terminal rated 20/32 (63%) 10/26 (38%) 4/20 (20%) 8/31 (26%) 14/25 (56%) 

First incidence (days) 529 612 589 550 562 e Logistic regression test P=0.003N P=0.152N P=0.003N P=0.007N P=0.428N 

Adenoma 

Overall rate 1/50 (2%) 2/50 (4%) 0/50 (0%) 0/50 (0%) 0/50 (0%) 

Fibroadenoma or Adenomaf 

Overall rate 26/50 (52%) 20/50 (40%) 9/50 (18%) 13/50 (26%) 23/50 (46%) 

Adjusted rate 67.8% 55.7% 33.2% 35.1% 66.7% 

Terminal rate 20/32 (63%) 11/26 (42%) 4/20 (20%) 8/31 (26%) 14/25 (56%) 

First incidence (days) 529 612 589 550 562 

Logistic regression test P=0.002N P=0.153N P=0.001N P=0.004N P=0.340N 

Carcinomag 

Overall rate 2/50 (4%) 3/50 (6%) 0/50 (0%) 0/50 (0%) 1/50 (2%) 

Adjusted rate 5.1% 10.3% 0.0% 0.0% 2.1% 

Terminal rate 1/32 (3%) 2/26 (8%) 0/20 (0%) 0/31 (0%) 0/25 (0%) 

First incidence (days) 228 697 —h — 562 

Logistic regression test P=0.048N P=0.483 P=0.288N P=0.213N P=0.713N 

Adenoma or Carcinomai 

Overall rate 3/50 (6%) 5/50 (10%) 0/50 (0%) 0/50 (0%) 1/50 (2%) 

Adjusted rate 7.4% 16.8% 0.0% 0.0% 2.1% 

Terminal rate 1/32 (3%) 3/26 (12%) 0/20 (0%) 0/31 (0%) 0/25 (0%) 

First incidence (days) 228 697 — — 562 

Logistic regression test P=0.013N P=0.347 P=0.130N P=0.109N P=0.466N 

Fibroadenoma, Adenoma, or Carcinomaj 

Overall rate 27/50 (54%) 23/50 (46%) 9/50 (18%) 13/50 (26%) 23/50 (46%) 

Adjusted rate 68.4% 62.7% 33.2% 35.1% 66.7% 

Terminal rate 20/32 (63%) 13/26 (50%) 4/20 (20%) 8/31 (26%) 14/25 (56%) 

First incidence (days) 228 612 589 550 562 

Logistic regression test P<0.001N P=0.268N P<0.001N P=0.003N P=0.346N 

a Historical incidence for 2-year NTP feed studies with untreated control groups (mean ± standard deviation): 524/1,301 

(40.3% ± 13.1%); range, 8%-58% b Number of animals with neoplasms per number of animals with mammary gland necropsied c Kaplan-Meier estimated neoplasm incidence at the end of the study after adjustment for intercurrent mortality d Observed incidence in animals surviving until the end of the study e In the control column are the P values associated with the trend test (the 10,000 ppm stop-exposure group was excluded from the trend test). 

In the exposure group columns are the P values corresponding to pairwise comparisons between the controls and that exposure group. The 

logistic regression test regards lesions in animals dying prior to terminal kill as nonfatal. A negative trend or lower incidence in an exposure 

group is indicated by N. f Historical incidence: 540/1,301 (41.5% ± 13.2%); range, 8%-62%
 g Historical incidence: 36/1,301 (2.8% ± 2.7%); range, 0%-8% h Not applicable; no neoplasms in animal group. i Historical incidence: 60/1,301 (4.6% ± 3.2%); range, 0%-10% j Historical incidence: 568/1,301 (43.7% ± 13.9%); range, 8%-64% 
46 Oxazepam, NTP TR 468 

Pituitary Gland: There were negative trends in the 

incidences of pituitary gland (pars distalis) adenoma in 

males (17/49, 12/50, 10/50, 2/48) and females (31/50, 

28/50, 21/50, 12/50) (Tables A3a and B3a). In males 

and females exposed to 5,000 ppm, incidences of 

adenoma were significantly less than those in the 

controls, and the incidences were below the historical 

ranges from 2-year NTP feed studies (Tables A4c and 

B4b). In females exposed to 5,000 ppm, the incidence 

of adenoma or carcinoma (combined) was also 

significantly less than that in the controls and was 

below the historical control range. There was a 

negative trend in the incidence of hyperplasia in male 

rats (9/49, 5/50, 3/50, 1/48; Table A5). In males 

exposed to 5,000 ppm, the incidence of hyperplasia 

was significantly less than that in the controls. The 

decreasing trends were most likely due at least in part 

to a combination of decreased body weights and 

survival in males and to decreased body weights in 

females, although it is unlikely that these reasons 

could fully account for the effects observed. 

Pancreas: The incidence of atrophy of the pancreatic 

acinus in males in the 5,000 ppm group was significantly less than that in the controls (17/50, 10/48, 

14/49, 1/50; Table A5), and the incidences of this 

lesion occurred with a negative trend. The lower 

incidences of this lesion may have been related to 

reduced survival of exposed males. 

GENETIC TOXICOLOGY 

Oxazepam (3 to 3,333 Fg/plate) did not induce 

mutations in Salmonella typhimurium strains TA97, 

TA98, TA100, TA102, or TA1535 when tested in a 

preincubation protocol with or without Aroclor 

1254-induced male Sprague-Dawley rat or Syrian 

hamster liver S9 (Table C1). In cytogenetic tests with 

cultured Chinese hamster ovary cells, oxazepam did 

not induce sister chromatid exchanges (Table C2) or 

chromosomal aberrations (Table C3), with or without 

S9. Cell cycle delay was noted at the 50 Fg/mL dose 

in the sister chromatid exchange test without S9; 

harvest time was extended to allow accumulation of 

sufficient second-division metaphase cells for analysis. 

Peripheral blood samples obtained from B6C3F1 mice

in a 14-week toxicity study were analyzed for 

frequency of micronucleated normochromatic erythrocytes; no increase in the frequency of micronucleated 

normochromatic erythrocytes was observed in any of 

the exposed groups (Table C4). 
PLATE 1 

Renal tubule adenoma in the kidney of a male F344/N rat administered 

2,500 ppm oxazepam for 2 years. Mass is well circumscribed with 

cells arranged in variably sized packets, some of which have central 

areas of cellular degeneration and hemorrhage (arrows). H&E; 35 ×
 

PLATE 2 

Higher magnification of Plate 1. Neoplastic cells resemble epithelial
 

cells of normal adjacent tubules and form small packets separated by
 

delicate fibrovascular septae. H&E; 175 ×
 

PLATE 3 

Mild renal tubule hyperplasia (arrowheads) in the kidney of a male 

F344/N rat administered 2,500 ppm oxazepam for 2 years. Group of 

hyperplastic tubules are surrounded by relatively normal renal 

tubules. Glomerulus (arrow). H&E; 140 ×
 

PLATE 4 

Higher magnification of Plate 3. Hyperplastic tubules are filled with
 

cuboidal to polygonal tubular epithelial cells. Note mitotic figure
 

(arrow). H&E; 230 ×
 
PLATE 5 

Mild nephropathy in a male F344/N rat administered 625 ppm 

oxazepam for 2 years. Note group of regenerative tubules with slight 

thickening of the tubular basement membrane (arrows) and slightly 

dilated tubules containing protein casts(*). H&E; 175× 

PLATE 6 

Marked nephropathy in a male F344/N rat administered 2,500 ppm 

oxazepam for 2 years. Note focal renal tubule regeneration, interstitial fibrosis, dilated glomeruli (arrows), and variably dilated renal 

tubules, many of which contain protein casts(*). H&E;45.5× 

PLATE 7 

Focal epithelial hyperplasia in the forestomach of a male F344/N rat 

administered 2,500 ppm oxazepam for 2 years. Note focal thickening 

of the mucosal epithelium (arrows). Normal mucosal epithelium is 

shown at left. H&E; 16.5× 

PLATE 8 

Higher magnification of Plate 7. Note hyperplastic mucosal epithelium. 

The adjacent submucosal is expanded by chronic active inflammation 

and edema (*).Focal areas of submucosal hemorrhage are also evident 

(arrows). H&E; 40× 
PLATE 9 

Marked focal epithelial hyperplasia in the forestomach of a male 

F344/N rat administered 2,500 ppm oxazepam for 2 years. The hyperplastic mucosal epithelium forms multiple thick papillary folds that 

project into the lumen. There is also thickening of the keratin layer 

(hyperkeratosis) covering the epithelial surface. H&E; 20 × 

PLATE 11 

Focal mucosal ulcer in the forestomach of a male F344/N rat administered 5,000 ppm oxazepam for 2 years. The cavity (ulcer) formed by 

the loss of the mucosal epithelium is partially filled with a coagulum 

of necrotic cellular debris and degenerate inflammatory cells (arrows). 

H&E; 16.5 × 

PLATE 10 

Higher magnification of Plate 9. Chronic active inflammation and 

edema are within the adjacent submucosal and extend into the muscle 

(tunica muscularis) layers (*). H&E; 33 × 

PLATE 12 

Higher magnification of Plate 11. Marked chronic active inflammation 

and fibrosis within the submucosa and extending into the muscle (tunica muscularis) layers (*). Note mucosal epithelial hyperplasia with 

hyperkeratosis at the margins of the ulcer (arrows). H&E; 33 × 
47 

DISCUSSION AND CONCLUSIONS
 

Evaluation of the toxicity and carcinogenicity of In female rats, adverse effects on body weights and 

oxazepam in F344/N rats was prompted by the finding survival were not nearly as severe as in males, alof a marked hepatocellular neoplasm response in though both body weights and survival were reduced 

similar studies with Swiss-Webster and B6C3F mice 1 in an exposure-related fashion. The incidences of 

(NTP, 1993; Bucher et al., 1994). Studies of the nephropathy were increased in females, but the 

carcinogenicity of oxazepam in Sprague-Dawley rats severities were mild. The difference between the 

were performed previously and reported to the FDA. responses of males and females to oxazepam appeared 

However, given the widespread use of benzo- to be in the unexpected and marked enhancement of 

diazepines and the fact that oxazepam is a common the nephropathy commonly seen in control male 

metabolite of several of the more widely used variants F344/N rats. Varying degrees of nephropathy norof this drug class, cancer studies in a second strain of mally develop in the aging rat, and this condition is 

rat were deemed necessary to examine possible worsened when the animals are maintained on a 

differences in response. relatively high protein diet, such as the NIH-07 diet 

used in these studies (Rao et al., 1993). Nephropathy 

No 13-week rat studies were performed prior to the is considered to be a major contributor to early 

2-year studies summarized in this report because there mortality in rats and likely accounts for the pattern of 

was some sense of urgency to begin the rat studies and deaths observed in this study. It is possible that this 

because relatively little useful information was kidney lesion would have been seen in certain 

obtained from the 13-week studies conducted in exposure groups in 13-week studies because nephroppreparation for the 2-year mouse studies. Instead, athy was more severe in the 10,000 ppm stopbased on information from the literature, a five-dose exposure group of males, 18 months after exposure 

2-year study was begun in anticipation that sufficient ceased. However, enhanced nephropathy was not seen 

information would be gained during the first 6 months in mice receiving oxazepam, nor was it reported in 

of the 2-year study to determine which exposure rats or mice in chronic studies with prazepam 

groups would be allowed to proceed to study termi- (de la Iglesia et al., 1981), temazepam (Robinson 

nation. Based on low body weight gains, groups of et al., 1984), or ripazepam (Fitzgerald et al., 1984), 

male and female rats exposed to 10,000 ppm were although some renal tubule dilatation in rats was 

removed from dosed feed and allowed to consume reported with the last compound. 

control diet until the end of the study. Groups consuming feed containing 1,250 ppm were terminated In the current study, the parathyroid gland hyperplasia 

because it was predicted that little additional informa- and fibrous osteodystrophy of bone that occurred in 

tion would be gained from these animals. the male rats are consistent sequelae to severe 

nephropathy and secondary hyperparathyroidism of 

In retrospect, the decision to forego performance of chronic renal failure (Leininger and Riley, 1990; Seely 

13-week studies was incorrect. The 2,500 and and Hildebrandt, 1990; Capen, 1994). Mineralization 

5,000 ppm exposure concentrations selected for the of the glandular stomach is also a common 

continuous administration portion of the study were manifestation of severe nephropathy and is due to 

sufficiently high to result in substantial reductions in hypercalcemia induced by secondary renal 

both body weight gains and in survival of male rats. hyperparathyroidism. It has been shown experiSurvival was somewhat reduced in the 625 ppm male mentally that stress-related ulceration of the glandular 

group, and mean body weights were also slightly stomach can be enhanced by either acidotic or nonlower in this group during most of the study. From acidotic renal insufficiency (Fischer et al., 1974), and 

the standpoint of body weight and survival, 625 ppm mineralization of the glandular stomach and the 

was sufficient for an adequate chronic toxicity and forestomach can be sequelae to uremia (Brown and 

carcinogenicity study in male rats. Hardisty, 1990). 
48 Oxazepam, NTP TR 468 

Male rats exposed to 2,500 or 5,000 ppm and female 

rats exposed to 2,500 ppm had increased incidences of 

epithelial hyperplasia, ulceration, and inflammation of 

the forestomach. Degenerative and proliferative 

forestomach lesions are relatively common in studies 

in which chemicals are administered orally (Gonipath 

et al., 1987). The spectrum of degenerative lesions 

includes erosions, ulceration, and necrosis with 

associated inflammation of the submucosa, which may 

extend to the serosal surface. Proliferative lesions 

range from mild hyperplasia to marked papillomatous 

hyperplasia of the squamous epithelium of the forestomach, with or without the development of papillomas. Papillomas were not noted in this study; 

however, severe papillary hyperplasia was observed in 

some animals. The increased incidences of 

these lesions in the forestomach of continuously exposed animals suggest that the development of these 

lesions was probably a direct effect of chemical administration. In the stop-exposure study, the significantly 

increased incidences of nonneoplastic lesions in the 

forestomach indicate a failure of these lesions to 

resolve during the prolonged recovery period. This is 

rather unexpected. It suggests that these lesions may 

have been due in part to the abrupt removal of the 

drug from the diet, eliciting stress related to dependence, coupled with compromised renal function later 

in the study. 

A few renal tubule adenomas were seen, principally in 

the 2,500 ppm group in the initial evaluation of 

kidneys of exposed male rats, although a dose 

response was not evident. Additional sections of the 

remaining embedded kidneys were taken and 

additional microscopic adenomas were observed. The 

NTP experience with multiple-step sectioning of 

kidneys has been reported by Eustis et al. (1994). In 

13 prior studies, additional renal tubule neoplasms and 

oncocytomas were observed with step sectioning in 

both control and exposed groups. Although no additional neoplasms were found in the control rat kidneys 

for many of the studies, as many as six were found in 

one study. Even greater numbers of additional 

neoplasms were found in some exposure groups. 

Eustis et al. (1994) noted that the studies in which 

additional renal neoplasms were found were also those 

in which nephropathy was more severe than usual, or 

those in which the chemical enhanced the nephropathy. This was the case in the present study with 

oxazepam. 

Although the renal tubule neoplasms occurred with a 

positive trend, this was considered an uncertain 

finding. The incidence of 14% in the 2,500 ppm 

group is similar to the upper range of neoplasms found 

in historical controls after step sectioning (Eustis 

et al., 1994). While it is unlikely that the 2,500, 

5,000, and 10,000 ppm stop-exposure groups 

incidences would all fall close to the upper range of 

historical control incidences by chance alone, the 

severe nephropathy complicated interpretation of these 

findings. There was no increase in renal tubule 

neoplasms in the 625 ppm group. Whether these renal 

neoplasms represent an intrinsic carcinogenic effect of 

oxazepam or are secondary to the oxazepam-enhanced 

nephropathy cannot be determined from these studies. 

There is no convincing evidence to suggest that 

oxazepam is mutagenic or has the ability to induce 

chromosomal aberrations or other adverse genetic 

effects. 

The effects of oxazepam on the liver of male and 

female rats were limited to centrilobular hepatocyte 

hypertrophy commonly seen with a wide variety of 

agents, including other benzodiazepines and barbiturates, and changes in the incidences of basophilic 

and clear cell foci. There was no evidence of an 

increase in hepatocellular neoplasms in male or female 

rats exposed to oxazepam. This is in sharp contrast to 

the increases in liver neoplasms reported with the two 

mouse strains studied earlier (NTP, 1993; Bucher 

et al., 1994). 

The reasons for the species differences in liver neoplasm response are not known. The response of the 

mouse liver to oxazepam includes a transient induction 

of hepatocyte replication, which, coupled with 

hepatocyte hypertrophy, accounts for the increase in 

liver weight. Increases in cytochrome P450 and 

b5 content and glucuronyl transferase activity are 

seen; however, there is little evidence to suggest 

that oxidative stress or cytotoxicity is induced 

(Bucher et al., 1994; Cunningham et al., 1994; Griffin 

et al., 1996). In similar studies reported in 

Appendix H, hepatocyte proliferation in rats was also 

transient and hypertrophy was a persistent change. 

Again, oxazepam did not induce significant cytotoxicity. In in vitro incubations of oxazepam with 

microsomes from human, rat, and mouse liver, 

evidence of covalent protein binding was found in all 

three cases, but the magnitude was greatest in rats, 
 

__________ 

Oxazepam, NTP TR 468 49 

followed by mice, and then humans (Griffin et al., 

1995a,b), suggesting that this activity is unrelated to 

the carcinogenic response. 

One area in which there are clear differences between 

rats and mice is in comparative metabolism. The 

metabolism of oxazepam is complex and has been 

extensively documented in the F344/N rat and the 

B6C3F and Swiss-Webster mouse (Griffin and Burka, 1 

1993, 1995). Oxidative metabolism (of the phenyl 

ring) occurs in both rats and mice (Griffin et al., 

1995c) but is more pronounced in rats. There are also 

differences in the major conjugation reactions with 

glucuronic acid and sulfate, as well as differences in 

fecal and urinary excretion patterns. On repeated 

dosing, there is a shift in the metabolite pattern in 

mice, but not rats, suggesting an induction of enzymes 

which are involved in oxazepam metabolism. Serum 

concentrations of oxazepam were higher at comparable 

dosed feed concentrations in mice (NTP, 1993) than in 

rats in the current study, but the differences appeared 

due at least in part to the relatively greater 

consumption of dosed feed by mice than rats on a 

body weight basis. Mice also eliminated less oxazepam in the feces than did rats and had a slightly 

longer terminal elimination half-life from plasma, 

suggesting that enterohepatic circulation may be 

greater in mice (Yuan et al., 1994; Griffin and Burka, 

1993, 1995). This may indicate a greater degree of 

exposure of the liver of mice to oxazepam and its 

metabolites when compared to rats. Nonetheless, as 

indicated earlier, despite considerable effort devoted to 

examining the basis for the differential carcinogenic 

response in rats and mice, no clear biochemical basis 

for this effect has been identified. 

Two recent epidemiology studies have evaluated the 

association between human cancers and benzodiazepine use. Neither examined oxazepam specifically. Rosenberg et al. (1995) did not find an association between sustained benzodiazepine use (at least 

4 days per week for at least 1 month, initiated at least 

2 years prior to hospital admission) and any one of 

11 cancers (breast, large bowel, malignant melanoma, 

lung, uterine endometrium, ovary, non-Hodgkin’s 

lymphoma, testis, Hodgkin’s disease, thyroid gland, 

and liver) in a large United States hospital-based 

surveillance study. Harlow and Cramer (1995) 

reported an association between prior use of benzodiazepines exceeding 1 to 6 months with subsequent 

development of ovarian cancer (adjusted odds ratio 

1.8, 95% CI 1.0 -3.1). These authors proposed that 

the induction of hepatic microsomal enzymes by 

benzodiazepines might enhance the metabolism of 

estrogen, thus stimulating higher gonadotropin levels. 

Ovarian neoplasms were not increased in female rats 

in the present studies or in studies with mice reported 

earlier (NTP, 1993). 

CONCLUSIONS 

In summary, under the conditions of these 2-year 

dosed-feed studies, there was equivocal evidence of 

carcinogenic activity* in male F344/N rats based on 

small increases in the incidences of renal tubule 

adenomas in exposed groups also exhibiting significantly enhanced nephropathy. There was no evidence 

of carcinogenic activity of oxazepam in female F344/N 

rats exposed to feed containing 625, 2,500, or 

5,000 ppm for 2 years or 10,000 ppm for 6 months. 

Administration of oxazepam to rats resulted in nonneoplastic lesions in the forestomach, glandular 

stomach, and small intestine as well as centrilobular 

hypertrophy of hepatocytes in the liver. In addition, 

nephropathy was increased in incidence in female rats 

and was markedly increased in severity in male rats, 

resulting in early mortality at the higher exposure 

concentrations. 

* Explanation of Levels of Evidence of Carcinogenic Activity is on page 9. A summary of the Technical Reports Review Subcommittee

 comments and the public discussion on this Technical Report appears on page 11. 
50 Oxazepam, NTP TR 468
 
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60 Oxazepam, NTP TR 468
 
 61 

APPENDIX A 

SUMMARY OF LESIONS IN MALE RATS 

IN THE 2-YEAR FEED STUDY 

OF OXAZEPAM 

TABLE A1 

TABLE A2 

TABLE A3a 

TABLE A3b 

TABLE A4a 

TABLE A4b 

TABLE A4c 

TABLE A5 

Summary of the Incidence of Neoplasms in Male Rats 

in the 2-Year Feed Study of Oxazepam .................................. 

Individual Animal Tumor Pathology of Male Rats 

in the 2-Year Feed Study of Oxazepam .................................. 

Statistical Analysis of Primary Neoplasms in Male Rats 

in the 2-Year Feed Study of Oxazepam .................................. 

Statistical Analysis of Primary Neoplasms in Male Rats 

in the 2-Year Stop-Exposure Feed Study of Oxazepam ........................ 

Historical Incidence of Renal Tubule Adenoma 

in Untreated Male F344/N Rats ....................................... 

Historical Incidence of Benign Adrenal Medulla Pheochromocytoma 

in Untreated Male F344/N Rats ....................................... 

Historical Incidence of Pituitary Gland (Pars Distalis) Adenoma 

in Untreated Male F344/N Rats ....................................... 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats 

in the 2-Year Feed Study of Oxazepam .................................. 

62 

66 

90 

96 

101 

101 

102 

103 
62 Oxazepam, NTP TR 468 

TABLE A1 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Feed Study of Oxazepama 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Disposition Summary 

Animals initially in study 50 50 50 50 50 

Early deaths

 Moribund 25 27 33 43 39

 Natural deaths 8 12 11 7 11 

Survivors

 Terminal sacrifice 17 11 6 

Animals examined microscopically 50 50 50 50 50 

Alimentary System 

Intestine large, colon (50) (47) (50) (50) (1) 

Polyp adenomatous 1 (2%) 

Intestine large, rectum (50) (48) (49) (50) (1) 

Polyp adenomatous 1 (2%) 

Intestine small, jejunum (49) (48) (46) (49) 

Carcinoma 2 (4%) 

Leiomyosarcoma 1 (2%) 

Liver (50) (50) (49) (50) (50) 

Fibrous histiocytoma, metastatic, lung 1 (2%) 

Hepatocellular carcinoma 1 (2%) 

Hepatocellular adenoma 1 (2%) 3 (6%) 1 (2%) 

Mesentery (7) (6) (4) (4) (5) 

Leiomyosarcoma, metastatic,

 intestine small, jejunum 1 (14%) 

Leiomyosarcoma, metastatic, stomach,

 glandular 1 (17%) 

Oral mucosa (1) 

Gingival, squamous cell carcinoma 1 (100%) 

Pancreas (50) (48) (49) (50) 

Adenoma 1 (2%) 

Fibrous histiocytoma, metastatic, lung 1 (2%) 

Acinus, adenoma 1 (2%) 1 (2%) 

Acinus, adenoma, mixed cell 1 (2%) 

Stomach, forestomach (50) (48) (50) (50) (49) 

Leiomyosarcoma 1 (2%) 

Stomach, glandular (50) (48) (50) (50) (47) 

Leiomyosarcoma 1 (2%) 

Tongue (1) (1) 

Squamous cell carcinoma 1 (100%) 

Squamous cell papilloma 1 (100%) 

Tooth (1) 

Odontoma 1 (100%) 

Cardiovascular System 

Heart (50) (50) (50) (50) (7) 

Schwannoma malignant 1 (2%) 
Oxazepam, NTP TR 468 63 

TABLE A1
 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Endocrine System 

Adrenal cortex (50) (50) (50) (50) 

Adenoma 1 (2%) 

Fibrous histiocytoma, metastatic, lung 1 (2%) 

Adrenal medulla (50) (50) (50) (50) (1) 

Pheochromocytoma malignant 1 (100%) 

Pheochromocytoma benign 9 (18%) 8 (16%) 5 (10%) 1 (2%) 

Bilateral, pheochromocytoma benign 5 (10%) 1 (2%) 1 (2%) 2 (4%) 

Islets, pancreatic (50) (48) (49) (50) 

Adenoma 1 (2%) 

Carcinoma 2 (4%) 

Pituitary gland (49) (50) (50) (48) (5) 

Pars distalis, adenoma 17 (35%) 12 (24%) 9 (18%) 2 (4%) 5 (100%) 

Pars distalis, adenoma, multiple 1 (2%) 

Thyroid gland (50) (49) (50) (50) (50) 

Bilateral, C-cell, adenoma 1 (2%) 2 (4%) 

C-cell, adenoma 9 (18%) 5 (10%) 4 (8%) 2 (4%) 1 (2%) 

C-cell, carcinoma 1 (2%) 

Follicular cell, adenoma 1 (2%) 1 (2%) 2 (4%) 2 (4%) 

Follicular cell, carcinoma 3 (6%) 3 (6%) 3 (6%) 4 (8%) 1 (2%) 

General Body System 

Peritoneum (2) (1) (1) (2) (1) 

Genital System 

Epididymis (50) (49) (50) (50) (1) 

Preputial gland (48) (50) (50) (49) (14) 

Adenoma 6 (13%) 9 (18%) 5 (10%) 3 (6%) 7 (50%) 

Carcinoma 1 (2%) 

Fibrous histiocytoma, metastatic, lung 1 (2%) 

Bilateral, adenoma 1 (2%) 1 (2%) 3 (21%) 

Seminal vesicle (50) (50) (50) (50) (1) 

Testes (50) (50) (50) (50) (48) 

Bilateral, interstitial cell, adenoma 35 (70%) 42 (84%) 47 (94%) 46 (92%) 44 (92%) 

Interstitial cell, adenoma 10 (20%) 6 (12%) 2 (4%) 1 (2%) 4 (8%) 

Hematopoietic System 

Bone marrow (50) (50) (50) (50) 

Fibrous histiocytoma, metastatic, lung 1 (2%) 

Lymph node (5) (8) (8) (1) (9) 

Deep cervical, carcinoma, metastatic,

 thyroid gland 1 (11%) 

Lymph node, mandibular (50) (49) (49) (50) (4) 

Lymph node, mesenteric (49) (49) (50) (47) (4) 

Spleen (50) (50) (50) (50) (33) 

Fibroma 1 (2%) 

Hemangiosarcoma 1 (2%) 1 (2%) 

Histiocytic sarcoma 1 (2%) 1 (2%) 

Thymus (49) (47) (49) (47) 

Thymoma malignant 1 (2%) 
64 Oxazepam, NTP TR 468 

TABLE A1
 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Integumentary System 

Mammary gland 

Adenoma 

Carcinoma 

Fibroadenoma 

Skin 

Fibroma 

Fibrosarcoma 

Keratoacanthoma 

Keratoacanthoma, multiple 

Liposarcoma 

Osteosarcoma 

Sarcoma 

Schwannoma malignant 

Squamous cell papilloma 

Sebaceous gland, adenoma 

(50) 

4 (8%) 

(50) 

3 (6%) 

2 (4%) 

3 (6%) 

1 (2%) 

3 (6%) 

2 (4%) 

1 (2%) 

(44) 

5 (11%) 

(49) 

1 (2%) 

3 (6%) 

5 (10%) 

(48) 

4 (8%) 

(49) 

1 (2%) 

1 (2%) 

1 (2%) 

1 (2%) 

(48) 

1 (2%) 

2 (4%) 

(50) 

2 (4%) 

2 (4%) 

1 (2%) 

1 (2%) 

(2) 

1 (50%) 

1 (50%) 

(8) 

2 (25%) 

1 (13%) 

2 (25%) 

2 (25%) 

Musculoskeletal System 

Bone 

Chordoma 

(50) (50) (50) 

1 (2%) 

(50) (4) 

Nervous System 

Brain 

Astrocytoma malignant 

Fibrous histiocytoma, metastatic, lung 

Oligodendroglioma malignant 

(50) (50) 

1 (2%) 

(50) 

1 (2%) 

1 (2%) 

(50) (2) 

Respiratory System 

Lung (50) 

Alveolar/bronchiolar adenoma 1 (2%) 

Alveolar/bronchiolar carcinoma 

Chordoma, metastatic, bone 

Fibrosarcoma, metastatic, skin 1 (2%) 

Fibrous histiocytoma 

Schwannoma malignant, metastatic, skin 1 (2%) 

(50) 

1 (2%) 

1 (2%) 

(50) 

1 (2%) 

1 (2%) 

1 (2%) 

(50) (3) 

Special Senses System 

Zymbal’s gland 

Carcinoma 

(1) 

1 (100%) 

(1) 

1 (100%) 

(1) 

1 (100%) 

Urinary System 

Kidney 

Fibrous histiocytoma, metastatic, lung 

Renal tubule, adenoma 

Urinary bladder 

(50) 

1 (2%) 

(50) 

(50) 

1 (2%) 

(50) 

(50) 

3 (6%) 

(50) 

(50) 

1 (2%) 

(50) 

(42) 

(1) 
65 

c 

Oxazepam, NTP TR 468 

TABLE A1
 

Summary of the Incidence of Neoplasms in Male Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Systemic Lesions 

Multiple organsb (50) (50) (50) (50) (50) 

Histiocytic sarcoma 1 (2%) 1 (2%) 

Leukemia mononuclear 27 (54%) 36 (72%) 33 (66%) 19 (38%) 34 (68%) 

Lymphoma malignant 1 (2%) 

Mesothelioma malignant 2 (4%) 2 (4%) 1 (2%) 1 (2%) 1 (2%) 

Neoplasm Summary 

Total animals with primary neoplasmsc 50 50 50 48 48 

Total primary neoplasms 160 151 135 99 116 

Total animals with benign neoplasms 47 50 50 47 48

 Total benign neoplasms 115 99 89 71 74 

Total animals with malignant neoplasms 38 43 40 25 35

 Total malignant neoplasms 45 52 46 28 42 

Total animals with metastatic neoplasms 3 2 1 1

 Total metastatic neoplasms 3 8 1 1 

a Number of animals examined microscopically at the site and the number of animals with neoplasm b Number of animals with any tissue examined microscopically 

Primary neoplasms: all neoplasms except metastatic neoplasms 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

66 Oxazepam, NTP TR 468 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 0 ppm 

4 4 4 4 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 6 6 6 

Number of Days on Study 7 8 9 9 1 1 3 4 5 7 8 9 0 0 2 8 8 8 8 8 8 9 9 9 9 

1 0 1 8 7 9 7 1 4 1 5 2 1 8 1 1 2 2 2 4 8 0 0 4 5 

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

Carcass ID Number 3 3 1 2 2 2 0 4 3 0 4 4 4 3 2 1 1 2 3 5 3 0 0 1 2 

0 2 9 5 9 7 6 3 5 7 4 8 1 1 2 7 2 8 7 0 9 4 9 8 1 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine large, colon + + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine large, rectum + + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine large, cecum + + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine small, duodenum + + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine small, jejunum + + + + + + + + + + + + + + + + + + + + + + + + + 

Carcinoma X 

Leiomyosarcoma 

Intestine small, ileum + + + + + + + + + + + + + + + + + + + + + + + + + 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + 

Hepatocellular carcinoma X 

Hepatocellular adenoma 

Mesentery + + 

Leiomyosarcoma, metastatic,

 intestine small, jejunum 

Pancreas + + + + + + + + + + + + + + + + + + + + + + + + + 

Acinus, adenoma 

Acinus, adenoma, mixed cell 

Salivary glands + + + + + + + + + + + + + + + + + + + + + + + + + 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + 

Tooth 

Odontoma 

Cardiovascular System 

Blood vessel + + + + + + + + + + + + + + + + + + + + + + + + + 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + 

Pheochromocytoma benign X X X X 

Bilateral, pheochromocytoma benign X X X X 

Islets, pancreatic + + + + + + + + + + + + + + + + + + + + + + + + + 

Adenoma X 

Carcinoma X X 

Parathyroid gland M M + + + M + + M + M + + + + + + M + + M + + + + 

Pituitary gland + + + + + + + + + + + + M + + + + + + + + + + + + 

Pars distalis, adenoma X X X X X 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + 

Bilateral, C-cell, adenoma 

C-cell, adenoma X X X X X 

Follicular cell, adenoma X 

Follicular cell, carcinoma X X 

General Body System 

Peritoneum + + 

+: Tissue examined microscopically M: Missing tissue X: Lesion present 

A: Autolysis precludes examination I: Insufficient tissue Blank: Not examined 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 67 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 0 ppm (continued)
 

6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 9 9 9 9 9 1 1 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

5 6 8 8 8 1 6 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Total 

Carcass ID Number 4 2 0 1 3 4 0 1 0 0 0 1 1 1 1 2 2 2 3 3 3 4 4 4 4 Tissues/ 

0 3 1 6 6 9 8 0 2 3 5 1 3 4 5 0 4 6 3 4 8 2 5 6 7 Tumors 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, colon + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, rectum + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, cecum + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine small, duodenum + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine small, jejunum + + + + + A + + + + + + + + + + + + + + + + + + + 49 

Carcinoma X 2 

Leiomyosarcoma X 1 

Intestine small, ileum + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Hepatocellular carcinoma 1 

Hepatocellular adenoma X 1 

Mesentery + + + + + 7 

Leiomyosarcoma, metastatic,

 intestine small, jejunum X 1 

Pancreas + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Acinus, adenoma X 1 

Acinus, adenoma, mixed cell X 1 

Salivary glands + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Tooth + 1 

Odontoma X 1 

Cardiovascular System 

Blood vessel + + + + + + + + + + + + + + + + + + + + + + + + 49 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Pheochromocytoma benign X X X X X 9 

Bilateral, pheochromocytoma benign X 5 

Islets, pancreatic + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Adenoma 1 

Carcinoma 2 

Parathyroid gland + + + + + + + + M + + + + M M + + M + + + + + + + 39 

Pituitary gland + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Pars distalis, adenoma X X X X X X X X X X X X 17 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Bilateral, C-cell, adenoma X 1 

C-cell, adenoma X X X X 9 

Follicular cell, adenoma 1 

Follicular cell, carcinoma X 3 

General Body System 

Peritoneum 2 
 

 

 

 

 

 

 

 

 

 

 

 

68 Oxazepam, NTP TR 468 

TABLE A2
 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 0 ppm (continued)
 

4 4 4 4 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 6 6 6 

Number of Days on Study 7 8 9 9 1 1 3 4 5 7 8 9 0 0 2 8 8 8 8 8 8 9 9 9 9 

1 0 1 8 7 9 7 1 4 1 5 2 1 8 1 1 2 2 2 4 8 0 0 4 5 

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

Carcass ID Number 3 3 1 2 2 2 0 4 3 0 4 4 4 3 2 1 1 2 3 5 3 0 0 1 2 

0 2 9 5 9 7 6 3 5 7 4 8 1 1 2 7 2 8 7 0 9 4 9 8 1 

Genital System 

Coagulating gland + + 

Epididymis + + + + + + + + + + + + + + + + + + + + + + + + + 

Preputial gland + + M + + + + + + + + + + + + + + + + + + + + M + 

Adenoma X 

Carcinoma X 

Bilateral, adenoma X 

Prostate + + + + + + + + + + + + + + + + + + + + + + + + + 

Seminal vesicle + + + + + + + + + + + + + + + + + + + + + + + + + 

Testes + + + + + + + + + + + + + + + + + + + + + + + + + 

Bilateral, interstitial cell, adenoma X X X X X X X X X X X X 

Interstitial cell, adenoma X X X X X X X X 

Hematopoietic System 

Bone marrow + + + + + + + + + + + + + + + + + + + + + + + + + 

Lymph node + + + 

Lymph node, mandibular + + + + + + + + + + + + + + + + + + + + + + + + + 

Lymph node, mesenteric + + + + + + + + + + + + + + + + + + + + + + + + M 

Spleen + + + + + + + + + + + + + + + + + + + + + + + + + 

Fibroma 

Thymus + + + + + + + + + + + + + + + + + + + + + + + + + 

Integumentary System 

Mammary gland + + + + + + + + + + + + + + + + + + + + + + + + + 

Fibroadenoma 

Skin + + + + + + + + + + + + + + + + + + + + + + + + + 

Fibroma 

Fibrosarcoma X 

Keratoacanthoma X X 

Sarcoma 

Schwannoma malignant X 

Squamous cell papilloma X X 

Sebaceous gland, adenoma X 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Lung + + + + + + + + + + + + + + + + + + + + + + + + + 

Alveolar/bronchiolar adenoma X 

Fibrosarcoma, metastatic, skin X 

Schwannoma malignant, metastatic, skin 

Nose + + + + + + + + + + + + + + + + + + + + + + + + + 

Trachea + + + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Ear 

Eye 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 69 

TABLE A2
 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 0 ppm (continued)
 

6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 9 

5 

9 

6 

9 

8 

9 

8 

9 

8 

1 

1 

1 

6 

2 

3 

3 

0 

3 

0 

3 

0 

3 

0 

3 

0 

3 

0 

3 

0 

3 

0 

3 

0 

3 

0 

3 

0 

3 

0 

3 

0 

3 

0 

3 

0 

3 

0 

3 

0 

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Total 

Carcass ID Number 4 

0 

2 

3 

0 

1 

1 

6 

3 

6 

4 

9 

0 

8 

1 

0 

0 

2 

0 

3 

0 

5 

1 

1 

1 

3 

1 

4 

1 

5 

2 

0 

2 

4 

2 

6 

3 

3 

3 

4 

3 

8 

4 

2 

4 

5 

4 

6 

4 

7 

Tissues/ 

Tumors 

Genital System 

Coagulating gland

Epididymis 

Preputial gland 

Adenoma 

Carcinoma

Bilateral, adenoma

Prostate 

Seminal vesicle 

Testes 

Bilateral, interstitial cell, adenoma 

Interstitial cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X X X X X X X X X X X X X X X X X X X 

X X 

2 

50 

48 

6 

1 

1 

50 

50 

50 

35 

10 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, mandibular 

Lymph node, mesenteric 

Spleen 

Fibroma 

Thymus 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ +

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X

+ + + + + + + + + + + + + + + + + + + M + + + + + 

50 

5 

50 

49 

50 

1 

49 

Integumentary System 

Mammary gland 

Fibroadenoma 

Skin 

Fibroma 

Fibrosarcoma 

Keratoacanthoma 

Sarcoma 

Schwannoma malignant 

Squamous cell papilloma

Sebaceous gland, adenoma

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X

X

X

X

X X

50 

4 

50 

3 

2 

3 

1 

3 

2 

1 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Respiratory System 

Lung 

Alveolar/bronchiolar adenoma

Fibrosarcoma, metastatic, skin

Schwannoma malignant, metastatic, skin 

Nose 

Trachea 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

50 

1 

1 

1 

50 

50 

Special Senses System 

Ear 

Eye + 

+

+

 1 

2 
 

 

 

70 Oxazepam, NTP TR 468 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 0 ppm (continued)
 

4 4 4 4 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 6 6 6 

Number of Days on Study 7 8 9 9 1 1 3 4 5 7 8 9 0 0 2 8 8 8 8 8 8 9 9 9 9 

1 0 1 8 7 9 7 1 4 1 5 2 1 8 1 1 2 2 2 4 8 0 0 4 5 

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

Carcass ID Number 3 3 1 2 2 2 0 4 3 0 4 4 4 3 2 1 1 2 3 5 3 0 0 1 2 

0 2 9 5 9 7 6 3 5 7 4 8 1 1 2 7 2 8 7 0 9 4 9 8 1 

Urinary System 

Kidney + + + + + + + + + + + + + + + + + + + + + + + + + 

Renal tubule, adenoma 

Urinary bladder + + + + + + + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs + + + + + + + + + + + + + + + + + + + + + + + + + 

Leukemia mononuclear X X X X X X X X X X X X X X 

Mesothelioma malignant X X 
 

 

 

Oxazepam, NTP TR 468 71 

TABLE A2
 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 0 ppm (continued)
 

6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 9 9 9 9 9 1 1 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

5 6 8 8 8 1 6 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Total 

Carcass ID Number 4 2 0 1 3 4 0 1 0 0 0 1 1 1 1 2 2 2 3 3 3 4 4 4 4 Tissues/ 

0 3 1 6 6 9 8 0 2 3 5 1 3 4 5 0 4 6 3 4 8 2 5 6 7 Tumors 

Urinary System 

Kidney + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Renal tubule, adenoma X 1 

Urinary bladder + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Systemic Lesions 

Multiple organs + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Leukemia mononuclear X X X X X X X X X X X X X 27 

Mesothelioma malignant 2 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

72 Oxazepam, NTP TR 468 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 625 ppm 

3 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 

Number of Days on Study 8 2 4 5 6 7 8 0 2 2 3 3 5 5 7 7 7 8 8 8 8 8 0 1 2 

6 6 8 2 6 3 1 1 3 4 6 6 0 7 1 2 8 5 5 6 6 9 4 4 0 

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

Carcass ID Number 5 5 6 9 6 6 5 9 6 8 5 7 7 5 8 8 7 7 8 9 9 6 7 5 5 

2 7 7 3 3 0 3 8 2 3 4 8 2 5 4 7 4 1 6 2 5 4 5 9 8 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine large, colon + + + + A A + + + + + + + + + A + + + + + + + + + 

Polyp adenomatous X 

Intestine large, rectum + + + + A A + + + + + + + + + + + + + + + + + + + 

Polyp adenomatous 

Intestine large, cecum + + + + A A + + + + + + + + + + + + + + + + + + + 

Intestine small, duodenum + + + + A A + + + + + + + + + + + + + + + + + + + 

Intestine small, jejunum + + + + A A + + + + + + + + + + + + + + + + + + + 

Intestine small, ileum + + A + A A + + + + + + + + + + + + + + + + + + + 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + 

Fibrous histiocytoma, metastatic, lung X 

Mesentery + + + 

Leiomyosarcoma, metastatic, stomach, glandular 

Pancreas + + + + A A + + + + + + + + + + + + + + + + + + + 

Adenoma 

Fibrous histiocytoma, metastatic, lung X 

Salivary glands + + + + + + + + + + + + + + + + + + + + + M + + + 

Stomach, forestomach + + + + A A + + + + + + + + + + + + + + + + + + + 

Stomach, glandular + + + + A A + + + + + + + + + + + + + + + + + + + 

Leiomyosarcoma 

Tongue + 

Squamous cell papilloma X 

Cardiovascular System 

Blood vessel + + + + + + + + + + + + + + + + + + + + + + + + + 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 

Schwannoma malignant 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 

Adenoma 

Fibrous histiocytoma, metastatic, lung X 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + 

Pheochromocytoma benign X X X 

Bilateral, pheochromocytoma benign 

Islets, pancreatic + + + + A A + + + + + + + + + + + + + + + + + + + 

Parathyroid gland + M + + + + M + M + + M + M + + + + + + + M + M + 

Pituitary gland + + + + + + + + + + + + + + + + + + + + + + + + + 

Pars distalis, adenoma X X X X X X 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + M + + + 

C-cell, adenoma X 

Follicular cell, carcinoma X 

General Body System 

Peritoneum + 

Genital System 

Epididymis + + + + + + + + + + + + M + + + + + + + + + + + + 

Preputial gland + + + + + + + + + + + + + + + + + + + + + + + + + 

Adenoma X X X X X X 

Fibrous histiocytoma, metastatic, lung X 

Prostate + + + + + + + + + + + + + + + + + + + + + + + + + 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 73 

TABLE A2
 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 625 ppm (continued)
 

6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 2 2 3 4 5 5 6 8 9 0 0 1 1 2 3 3 3 3 3 3 3 3 3 3 3 

5 8 4 2 1 2 7 2 8 2 9 2 4 2 0 0 0 0 0 0 0 0 0 0 0 

0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Total 

Carcass ID Number 8 8 7 8 5 9 0 6 6 6 9 6 5 8 6 7 7 7 7 8 8 9 9 9 9 Tissues/ 

9 0 3 2 1 7 0 6 5 8 1 9 6 5 1 0 6 7 9 1 8 0 4 6 9 Tumors 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, colon + + + + + + + + + + + + + + + + + + + + + + + + + 47 

Polyp adenomatous 1 

Intestine large, rectum + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Polyp adenomatous X 1 

Intestine large, cecum + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Intestine small, duodenum + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Intestine small, jejunum + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Intestine small, ileum + + + + + + + + + + + + + + + + + + + + + + + + + 47 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Fibrous histiocytoma, metastatic, lung 1 

Mesentery + + + 6 

Leiomyosarcoma, metastatic, stomach, glandular X 1 

Pancreas + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Adenoma X 1 

Fibrous histiocytoma, metastatic, lung 1 

Salivary glands + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Leiomyosarcoma X 1 

Tongue 1 

Squamous cell papilloma 1 

Cardiovascular System 

Blood vessel + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Schwannoma malignant X 1 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Adenoma X 1 

Fibrous histiocytoma, metastatic, lung 1 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Pheochromocytoma benign X X X X X 8 

Bilateral, pheochromocytoma benign X 1 

Islets, pancreatic + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Parathyroid gland + + + + + + + + + + + + + + + + + + + + M + + + M 41 

Pituitary gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Pars distalis, adenoma X X X X X X 12 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + 49 

C-cell, adenoma X X X X 5 

Follicular cell, carcinoma X X 3 

General Body System 

Peritoneum 1 

Genital System 

Epididymis + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Preputial gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Adenoma X X X 9 

Fibrous histiocytoma, metastatic, lung 1 

Prostate + + + + + + + + + + + + + + + + + + + + + + + + + 50 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

74 Oxazepam, NTP TR 468 

TABLE A2
 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 625 ppm (continued)
 

3 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 

Number of Days on Study 8 

6 

2 

6 

4 

8 

5 

2 

6 

6 

7 

3 

8 

1 

0 

1 

2 

3 

2 

4 

3 

6 

3 

6 

5 

0 

5 

7 

7 

1 

7 

2 

7 

8 

8 

5 

8 

5 

8 

6 

8 

6 

8 

9 

0 

4 

1 

4 

2 

0 

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

Carcass ID Number 5 

2 

5 

7 

6 

7 

9 

3 

6 

3 

6 

0 

5 

3 

9 

8 

6 

2 

8 

3 

5 

4 

7 

8 

7 

2 

5 

5 

8 

4 

8 

7 

7 

4 

7 

1 

8 

6 

9 

2 

9 

5 

6 

4 

7 

5 

5 

9 

5 

8 

Genital System (continued) 

Seminal vesicle 

Testes 

Bilateral, interstitial cell, adenoma 

Interstitial cell, adenoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X X X X X X X X X X X X X X X X 

X X X X X 

Hematopoietic System 

Bone marrow 

Fibrous histiocytoma, metastatic, lung 

Lymph node 

Lymph node, mandibular 

Lymph node, mesenteric 

Spleen 

Hemangiosarcoma 

Histiocytic sarcoma 

Thymus 

Thymoma malignant 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + 

+ + + + + + + + + + + + + + + + + + + + + M + + + 

+ + M + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + M + + + + + + + + + + + + 

X 

Integumentary System 

Mammary gland 

Fibroadenoma 

Skin 

Fibroma 

Fibrosarcoma 

Keratoacanthoma 

+ + M + + M + + + M M + + + + + + + + + + M + + + 

X 

+ + + + + + + + + + + + + + + + + + + + + M + + + 

X 

X X 

X X X 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain 

Fibrous histiocytoma, metastatic, lung 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

Respiratory System 

Lung 

Alveolar/bronchiolar carcinoma 

Fibrous histiocytoma 

Nose 

Trachea 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Eye 

Zymbal’s gland 

Carcinoma 

+ 

X 

+ 

Urinary System 

Kidney 

Fibrous histiocytoma, metastatic, lung 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 75 

TABLE A2
 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 625 ppm (continued)
 

6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 2 2 3 4 5 5 6 8 9 0 0 1 1 2 3 3 3 3 3 3 3 3 3 3 3 

5 8 4 2 1 2 7 2 8 2 9 2 4 2 0 0 0 0 0 0 0 0 0 0 0 

0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Total 

Carcass ID Number 8 8 7 8 5 9 0 6 6 6 9 6 5 8 6 7 7 7 7 8 8 9 9 9 9 Tissues/ 

9 0 3 2 1 7 0 6 5 8 1 9 6 5 1 0 6 7 9 1 8 0 4 6 9 Tumors 

Genital System (continued) 

Seminal vesicle + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Testes + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Bilateral, interstitial cell, adenoma X X X X X X X X X X X X X X X X X X X X X X 42 

Interstitial cell, adenoma X 6 

Hematopoietic System 

Bone marrow + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Fibrous histiocytoma, metastatic, lung 1 

Lymph node + + + 8 

Lymph node, mandibular + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Lymph node, mesenteric + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Spleen + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Hemangiosarcoma X 1 

Histiocytic sarcoma X 1 

Thymus + + + + + + + + + + M + + + + + + + + + + + + M + 47 

Thymoma malignant 1 

Integumentary System 

Mammary gland + + + + + + + + + + + + + + + + + + M + + + + + + 44 

Fibroadenoma X X X X 5 

Skin + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Fibroma 1 

Fibrosarcoma X 3 

Keratoacanthoma X X 5 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Fibrous histiocytoma, metastatic, lung 1 

Respiratory System 

Lung + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Alveolar/bronchiolar carcinoma X 1 

Fibrous histiocytoma 1 

Nose + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Trachea + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Special Senses System 

Eye + + 3 

Zymbal’s gland 1 

Carcinoma 1 

Urinary System 

Kidney + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Fibrous histiocytoma, metastatic, lung 1 

Urinary bladder + + + + + + + + + + + + + + + + + + + + + + + + + 50 

50 
 

 

 

76 Oxazepam, NTP TR 468 

TABLE A2
 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 625 ppm (continued)
 

3 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 

Number of Days on Study 8 2 4 5 6 7 8 0 2 2 3 3 5 5 7 7 7 8 8 8 8 8 0 1 2 

6 6 8 2 6 3 1 1 3 4 6 6 0 7 1 2 8 5 5 6 6 9 4 4 0 

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

Carcass ID Number 5 5 6 9 6 6 5 9 6 8 5 7 7 5 8 8 7 7 8 9 9 6 7 5 5 

2 7 7 3 3 0 3 8 2 3 4 8 2 5 4 7 4 1 6 2 5 4 5 9 8 

Systemic Lesions 

Multiple organs + + + + + + + + + + + + + + + + + + + + + + + + + 

Histiocytic sarcoma 

Leukemia mononuclear X X X X X X X X X X X X X X X X X 

Mesothelioma malignant X 
 

 

Oxazepam, NTP TR 468 77 

TABLE A2
 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 625 ppm (continued)
 

6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 2 2 3 4 5 5 6 8 9 0 0 1 1 2 3 3 3 3 3 3 3 3 3 3 3 

5 8 4 2 1 2 7 2 8 2 9 2 4 2 0 0 0 0 0 0 0 0 0 0 0 

0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Total 

Carcass ID Number 8 8 7 8 5 9 0 6 6 6 9 6 5 8 6 7 7 7 7 8 8 9 9 9 9 Tissues/ 

9 0 3 2 1 7 0 6 5 8 1 9 6 5 1 0 6 7 9 1 8 0 4 6 9 Tumors 

Systemic Lesions 

Multiple organs + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Histiocytic sarcoma X 1 

Leukemia mononuclear X X X X X X X X X X X X X X X X X X X 36 

Mesothelioma malignant X 2 
 

 

 

 

 

 

 

 

 

 

78 Oxazepam, NTP TR 468 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 2,500 ppm 

3 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 

Number of Days on Study 8 0 1 2 4 7 0 2 5 5 6 7 7 7 9 9 0 0 1 1 2 2 3 4 4 

1 0 5 4 0 9 7 6 4 8 8 0 1 6 6 9 0 5 3 3 0 6 3 1 1 

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 

Carcass ID Number 9 8 5 6 9 6 9 6 9 9 5 9 5 7 6 7 7 6 6 8 6 8 9 7 9 

3 6 5 1 1 7 8 2 4 7 4 9 7 3 5 1 8 4 3 0 9 5 5 5 2 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine large, colon + + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine large, rectum + + A + + + + + + + + + + + + + + + + + + + + + + 

Intestine large, cecum + + + + M + + + + + + + + + + + + + + + + + + + + 

Intestine small, duodenum A + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine small, jejunum A A A + A + + + + + + + + + + + + + + + + + + + + 

Intestine small, ileum A A A + A + + + + + + + + + + + + + + + + + + + + 

Liver A + + + + + + + + + + + + + + + + + + + + + + + + 

Mesentery + + + 

Oral mucosa 

Gingival, squamous cell carcinoma 

Pancreas A + + + + + + + + + + + + + + + + + + + + + + + + 

Acinus, adenoma X 

Salivary glands + + + + + + + + + + + + + + + + + + + + + + + + + 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + 

Leiomyosarcoma X 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + 

Cardiovascular System 

Blood vessel + + + + + + + + + + + + + + + + + + + + + + + + + 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + 

Pheochromocytoma benign 

Bilateral, pheochromocytoma benign 

Islets, pancreatic A + + + + + + + + + + + + + + + + + + + + + + + + 

Parathyroid gland + M + M + + M + + M + + + + + + + + + + + + + + + 

Pituitary gland + + + + + + + + + + + + + + + + + + + + + + + + + 

Pars distalis, adenoma X 

Pars distalis, adenoma, multiple 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + 

Bilateral, C-cell, adenoma 

C-cell, adenoma X X 

Follicular cell, adenoma X 

Follicular cell, carcinoma X 

General Body System 

Peritoneum + 

Genital System 

Epididymis + + + + + + + + + + + + + + + + + + + + + + + + + 

Preputial gland + + + + + + + + + + + + + + + + + + + + + + + + + 

Adenoma X X 

Prostate + + + + + + + + + + + + + + + + + + + + + + + + + 

Seminal vesicle + + + + + + + + + + + + + + + + + + + + + + + + + 

Testes + + + + + + + + + + + + + + + + + + + + + + + + + 

Bilateral, interstitial cell, adenoma X X X X X X X X X X X X X X X X X X X X X X 

Interstitial cell, adenoma X X 
 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 79 

TABLE A2
 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 2,500 ppm (continued)
 

6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 5 5 5 5 6 6 6 7 7 8 8 8 8 8 9 0 0 0 1 3 3 3 3 3 3 

3 5 9 9 2 3 3 3 6 0 1 4 7 9 5 1 2 5 6 0 0 0 0 0 0 

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 Total 

Carcass ID Number 5 5 8 8 6 7 9 5 6 8 8 7 8 7 8 7 5 7 5 5 6 7 8 9 0 Tissues/ 

3 2 1 8 8 2 0 1 6 2 9 0 7 6 3 7 6 9 9 8 0 4 4 6 0 Tumors 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, colon + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, rectum + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Intestine large, cecum + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Intestine small, duodenum + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Intestine small, jejunum + + + + + + + + + + + + + + + + + + + + + + + + + 46 

Intestine small, ileum + + + + + + + + + + + + + + + + + + + + + + + + + 46 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Mesentery + 4 

Oral mucosa + 1 

Gingival, squamous cell carcinoma X 1 

Pancreas + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Acinus, adenoma 1 

Salivary glands + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Leiomyosarcoma 1 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Cardiovascular System 

Blood vessel + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Pheochromocytoma benign X X X X X 5 

Bilateral, pheochromocytoma benign X 1 

Islets, pancreatic + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Parathyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + 46 

Pituitary gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Pars distalis, adenoma X X X X X X X X 9 

Pars distalis, adenoma, multiple X 1 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Bilateral, C-cell, adenoma X X 2 

C-cell, adenoma X X 4 

Follicular cell, adenoma 1 

Follicular cell, carcinoma X X 3 

General Body System 

Peritoneum 1 

Genital System 

Epididymis + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Preputial gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Adenoma X X X 5 

Prostate + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Seminal vesicle + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Testes + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Bilateral, interstitial cell, adenoma X X X X X X X X X X X X X X X X X X X X X X X X X 47 

Interstitial cell, adenoma 2 
 

 

 

 

 

 

 

 

 

 

 

 

80 Oxazepam, NTP TR 468 

TABLE A2
 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 2,500 ppm (continued)
 

Number of Days on Study 

3 

8 

1 

4 

0 

0 

4 

1 

5 

4 

2 

4 

4 

4 

0 

4 

7 

9 

5 

0 

7 

5 

2 

6 

5 

5 

4 

5 

5 

8 

5 

6 

8 

5 

7 

0 

5 

7 

1 

5 

7 

6 

5 

9 

6 

5 

9 

9 

6 

0 

0 

6 

0 

5 

6 

1 

3 

6 

1 

3 

6 

2 

0 

6 

2 

6 

6 

3 

3 

6 

4 

1 

6 

4 

1 

Carcass ID Number 

1 

9 

3 

1 

8 

6 

1 

5 

5 

1 

6 

1 

1 

9 

1 

1 

6 

7 

1 

9 

8 

1 

6 

2 

1 

9 

4 

1 

9 

7 

1 

5 

4 

1 

9 

9 

1 

5 

7 

1 

7 

3 

1 

6 

5 

1 

7 

1 

1 

7 

8 

1 

6 

4 

1 

6 

3 

1 

8 

0 

1 

6 

9 

1 

8 

5 

1 

9 

5 

1 

7 

5 

1 

9 

2 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, mandibular 

Lymph node, mesenteric 

Spleen 

Hemangiosarcoma 

Histiocytic sarcoma 

Thymus 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

M 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

M 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

Integumentary System 

Mammary gland 

Fibroadenoma 

Skin 

Fibroma 

Keratoacanthoma 

Osteosarcoma 

Squamous cell papilloma 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

M 

M 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

M 

+ 

Musculoskeletal System 

Bone 

Chordoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain 

Astrocytoma malignant 

Oligodendroglioma malignant 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Chordoma, metastatic, bone 

Nose 

Trachea 

Special Senses System 

Eye 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

Urinary System 

Kidney 

Renal tubule, adenoma 

Urinary bladder 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

Systemic Lesions 

Multiple organs 

Histiocytic sarcoma 

Leukemia mononuclear 

Mesothelioma malignant 

+ 

X 

+ 

X 

+ 

X 

+ + 

X 

+ 

X 

+ 

X 

+ + 

X 

+ 

X 

+ 

X 

+ + 

X 

+ 

X 

+ + 

X 

+ 

X 

+ 

X 

+ 

X 

+ 

X 

+ + 

X 

+ 

X 

+ 

X 

+ 

X 
 

 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 81 

TABLE A2
 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 2,500 ppm (continued)
 

6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 5 5 5 5 6 6 6 7 7 8 8 8 8 8 9 0 0 0 1 3 3 3 3 3 3 

3 5 9 9 2 3 3 3 6 0 1 4 7 9 5 1 2 5 6 0 0 0 0 0 0 

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 Total 

Carcass ID Number 5 5 8 8 6 7 9 5 6 8 8 7 8 7 8 7 5 7 5 5 6 7 8 9 0 Tissues/ 

3 2 1 8 8 2 0 1 6 2 9 0 7 6 3 7 6 9 9 8 0 4 4 6 0 Tumors 

Hematopoietic System 

Bone marrow + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Lymph node 8 

Lymph node, mandibular + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Lymph node, mesenteric + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Spleen + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Hemangiosarcoma X 1 

Histiocytic sarcoma X 1 

Thymus + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Integumentary System 

Mammary gland + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Fibroadenoma X X X X 4 

Skin + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Fibroma 1 

Keratoacanthoma X 1 

Osteosarcoma 1 

Squamous cell papilloma X 1 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Chordoma X 1 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Astrocytoma malignant X 1 

Oligodendroglioma malignant X 1 

Respiratory System 

Lung + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Alveolar/bronchiolar adenoma X 1 

Alveolar/bronchiolar carcinoma X 1 

Chordoma, metastatic, bone X 1 

Nose + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Trachea + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Special Senses System 

Eye + + 2 

Urinary System 

Kidney + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Renal tubule, adenoma X X 3 

Urinary bladder + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Systemic Lesions 

Multiple organs + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Histiocytic sarcoma X 1 

Leukemia mononuclear X X X X X X X X X X X X X X 33 

Mesothelioma malignant 1 
 

 

 

 

 

 

 

 

 

 

 

 

82 Oxazepam, NTP TR 468 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 5,000 ppm 

Number of Days on Study 

2 2 2 4 4 4 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 

2 2 3 2 3 3 3 4 5 5 5 6 9 9 0 1 1 1 2 2 2 2 2 2 3 

3 4 7 2 2 9 9 2 1 1 2 7 8 8 7 2 6 9 1 6 8 9 9 9 0 

Carcass ID Number 

2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 

0 3 1 0 3 0 0 4 2 2 1 4 1 1 1 0 4 4 3 4 4 2 3 5 4 

9 5 0 8 7 1 7 0 3 6 3 5 2 4 6 6 9 8 1 4 3 4 4 0 6 

Alimentary System 

Esophagus 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Hepatocellular adenoma 

Mesentery 

Pancreas 

Salivary glands 

Stomach, forestomach 

Stomach, glandular 

Tongue 

Squamous cell carcinoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + A + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + M + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X 

+ 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ 

X 

Cardiovascular System 

Blood vessel + + + + + + + + + + + + + + + + + + + + + + + + + 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + 

Pheochromocytoma benign X 

Bilateral, pheochromocytoma benign X X 

Islets, pancreatic + + + + + + + + + + + + + + + + + + + + + + + + + 

Parathyroid gland + M M + M + + M + M + + + M + + M + + + M M + + + 

Pituitary gland + + + + + + + M + + + + + + + + + + + + + + + + + 

Pars distalis, adenoma X 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + 

C-cell, adenoma X 

Follicular cell, adenoma 

Follicular cell, carcinoma X X 

General Body System 

Peritoneum + 

Genital System 

Epididymis + + + + + + + + + + + + + + + + + + + + + + + + + 

Preputial gland + + + + + + + + + + + + + + + + + + + + + + + + + 

Adenoma X 

Bilateral, adenoma X 

Prostate + + + + + + + + + + + + + + + + + + + + + + + + + 

Seminal vesicle + + + + + + + + + + + + + + + + + + + + + + + + + 

Testes + + + + + + + + + + + + + + + + + + + + + + + + + 

Bilateral, interstitial cell, adenoma X X X X X X X X X X X X X X X X X X X X X 

Interstitial cell, adenoma X 
 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 83 

TABLE A2
 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 5,000 ppm (continued)
 

5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 7 7 7 

Number of Days on Study 3 4 4 4 5 6 6 6 7 7 7 8 0 0 1 1 2 2 3 3 4 8 0 1 1 

0 1 1 3 0 2 2 2 5 6 7 5 5 5 0 8 0 8 1 4 7 8 5 0 2 

2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Total 

Carcass ID Number 4 2 3 2 3 1 1 1 0 2 4 3 2 4 3 2 3 0 0 3 2 1 2 0 1 Tissues/ 

7 0 6 7 0 5 7 9 2 5 2 2 8 1 3 2 9 3 5 8 9 1 1 4 8 Tumors 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, colon + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, rectum + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, cecum + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine small, duodenum + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine small, jejunum + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Intestine small, ileum + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Hepatocellular adenoma 3 

Mesentery + + + 4 

Pancreas + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Salivary glands + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Tongue 1 

Squamous cell carcinoma 1 

Cardiovascular System 

Blood vessel + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Pheochromocytoma benign 1 

Bilateral, pheochromocytoma benign 2 

Islets, pancreatic + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Parathyroid gland + + + + + + + + + + + + + + + + + + + M + + + + + 40 

Pituitary gland + + + + + + + + + + + + + + + + + + + M + + + + + 48 

Pars distalis, adenoma X 2 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

C-cell, adenoma X 2 

Follicular cell, adenoma X X 2 

Follicular cell, carcinoma X X 4 

General Body System 

Peritoneum +

Genital System 

Epididymis + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Preputial gland + + + + + + + + + + + + + + + + + + + + M + + + + 49 

Adenoma X X 3 

Bilateral, adenoma 1 

Prostate + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Seminal vesicle + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Testes + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Bilateral, interstitial cell, adenoma X X X X X X X X X X X X X X X X X X X X X X X X X 46 

Interstitial cell, adenoma 1 

 2 
 

 

 

 

 

 

 

 

84 Oxazepam, NTP TR 468 

TABLE A2
 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 5,000 ppm (continued)
 

Number of Days on Study 

2 

2 

3 

2 

2 

4 

2 

3 

7 

4 

2 

2 

4 

3 

2 

4 

3 

9 

4 

3 

9 

4 

4 

2 

4 

5 

1 

4 

5 

1 

4 

5 

2 

4 

6 

7 

4 

9 

8 

4 

9 

8 

5 

0 

7 

5 

1 

2 

5 

1 

6 

5 

1 

9 

5 

2 

1 

5 

2 

6 

5 

2 

8 

5 

2 

9 

5 

2 

9 

5 

2 

9 

5 

3 

0 

Carcass ID Number 

2 

0 

9 

2 

3 

5 

2 

1 

0 

2 

0 

8 

2 

3 

7 

2 

0 

1 

2 

0 

7 

2 

4 

0 

2 

2 

3 

2 

2 

6 

2 

1 

3 

2 

4 

5 

2 

1 

2 

2 

1 

4 

2 

1 

6 

2 

0 

6 

2 

4 

9 

2 

4 

8 

2 

3 

1 

2 

4 

4 

2 

4 

3 

2 

2 

4 

2 

3 

4 

2 

5 

0 

2 

4 

6 

Hematopoietic System 

Bone marrow 

Lymph node 

Lymph node, mandibular 

Lymph node, mesenteric 

Spleen 

Thymus 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + M + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Integumentary System 

Mammary gland 

Carcinoma 

Fibroadenoma 

Skin 

Fibroma 

Keratoacanthoma 

Keratoacanthoma, multiple 

Liposarcoma 

+ + + + + + + + + + + + + + + + + + + M + + + + + 

X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Lung 

Nose 

Trachea 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Eye 

Zymbal’s gland 

Carcinoma 

+ 

Urinary System 

Kidney 

Renal tubule, adenoma 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear 

Mesothelioma malignant 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X X X X X 

X 
 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 85 

TABLE A2
 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 5,000 ppm (continued)
 

5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 7 7 7 

Number of Days on Study 3 4 4 4 5 6 6 6 7 7 7 8 0 0 1 1 2 2 3 3 4 8 0 1 1 

0 1 1 3 0 2 2 2 5 6 7 5 5 5 0 8 0 8 1 4 7 8 5 0 2 

2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Total 

Carcass ID Number 4 2 3 2 3 1 1 1 0 2 4 3 2 4 3 2 3 0 0 3 2 1 2 0 1 Tissues/ 

7 0 6 7 0 5 7 9 2 5 2 2 8 1 3 2 9 3 5 8 9 1 1 4 8 Tumors 

Hematopoietic System 

Bone marrow + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Lymph node + 1 

Lymph node, mandibular + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Lymph node, mesenteric + + + + + + + + + M M + + + + + + + + + + + + + + 47 

Spleen + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Thymus M + + + + + + M + M + + + + + + + + + + + + + + + 47 

Integumentary System 

Mammary gland + + + + + M + + + + + + + + + + + + + + + + + + + 48 

Carcinoma 1 

Fibroadenoma X 2 

Skin + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Fibroma X X 2 

Keratoacanthoma X 2 

Keratoacanthoma, multiple X 1 

Liposarcoma 1 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Lung + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Nose + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Trachea + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Special Senses System 

Eye 1 

Zymbal’s gland + 1 

Carcinoma X 1 

Urinary System 

Kidney + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Renal tubule, adenoma X 1 

Urinary bladder + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Systemic Lesions 

Multiple organs + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Leukemia mononuclear X X X X X X X X X X 19 

Mesothelioma malignant 1 

50 

50 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

86 Oxazepam, NTP TR 468 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 10,000 ppm 

(Stop-Exposure) 

3 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 

Number of Days on Study 1 

7 

8 

0 

8 

4 

9 

0 

9 

8 

4 

2 

5 

8 

6 

4 

6 

7 

7 

2 

8 

4 

8 

5 

8 

7 

9 

0 

9 

0 

9 

6 

9 

6 

0 

5 

1 

3 

1 

3 

1 

3 

1 

4 

1 

4 

1 

6 

1 

8 

2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 

Carcass ID Number 5 7 5 6 7 8 5 5 9 8 8 9 6 6 8 5 7 9 6 7 7 5 9 7 5 

1 8 9 8 9 5 2 3 9 1 9 0 2 9 7 5 5 3 3 2 4 8 6 6 6 

Alimentary System 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Liver 

+ 

+ 

+ 

A + + A + + + + A + + + + + + + + + A + + + + A + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Hepatocellular adenoma 

Mesentery 

Stomach, forestomach 

Stomach, glandular 

X 

+ + + + 

+ + + A + + + + + + + + + + + + + + + + + + + + + 

A + + A + + + + A + + + + + + + + + + + + + + + + 

Cardiovascular System 

Heart + 

Endocrine System 

Adrenal medulla 

Pheochromocytoma malignant 

Parathyroid gland 

Pituitary gland 

Pars distalis, adenoma 

Thyroid gland 

C-cell, adenoma 

C-cell, carcinoma 

Follicular cell, adenoma 

Follicular cell, carcinoma 

+ + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

General Body System 

Peritoneum + 

Genital System 

Epididymis 

Preputial gland 

Adenoma 

+ + + 

X 

+ 

+ 

+ + 

X X 

Bilateral, adenoma 

Seminal vesicle 

X 

Testes + + + + + + + + + + + + + + + + + + + + + + + 

Bilateral, interstitial cell, adenoma 

Interstitial cell, adenoma 

X X X X 

X 

X X 

X X X 

X X X X X X X X X X X X X 

Hematopoietic System 

Lymph node 

Deep cervical, carcinoma, metastatic,

 thyroid gland 

Lymph node, mandibular 

Lymph node, mesenteric 

Spleen 

+ + + 

+ + 

+ + 

+ + + + + + 

+ 

+ + 

+ + 

+ + + + + 

+ 

+ + + + 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 87 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 10,000 ppm 

(Stop-Exposure) (continued) 

6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 7 7 7 7 

Number of Days on Study 2 2 3 3 3 4 4 4 4 4 5 5 7 8 8 9 9 9 9 9 9 0 1 1 2 

0 7 1 4 8 1 1 1 5 7 3 9 0 1 7 0 1 2 4 6 7 2 9 9 2 

2 2 2 2 2 2 2 2 2 2 2 3 2 2 2 2 2 2 2 2 2 2 2 2 2 Total 

Carcass ID Number 9 9 9 9 6 6 6 8 6 9 8 0 8 6 8 8 7 7 5 7 6 9 5 7 8 Tissues/ 

4 5 7 8 5 0 1 3 4 2 0 0 4 7 2 8 7 0 7 3 6 1 4 1 6 Tumors 

Alimentary System 

Intestine large, colon 1 

Intestine large, rectum 1 

Intestine large, cecum 1 

Intestine small, duodenum + + + + + + + + + + + + + + + + + A + + + + + + + 44 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Hepatocellular adenoma 1 

Mesentery + 5 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + 47 

Cardiovascular System 

Heart + + + + + + 7 

Endocrine System 

Adrenal medulla + 1 

Pheochromocytoma malignant X 1 

Parathyroid gland + + + + + + + + 13 

Pituitary gland + + + + + 5 

Pars distalis, adenoma X X X X X 5 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

C-cell, adenoma X 1 

C-cell, carcinoma X 1 

Follicular cell, adenoma X X 2 

Follicular cell, carcinoma X 1 

General Body System 

Peritoneum

Genital System 

Epididymis 1 

Preputial gland + + + + + + + + 14 

Adenoma X X X X 7 

Bilateral, adenoma X X 3 

Seminal vesicle + 1 

Testes + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Bilateral, interstitial cell, adenoma X X X X X X X X X X X X X X X X X X X X X X X X X 44 

Interstitial cell, adenoma 4 

Hematopoietic System 

Lymph node + + + 9 

Deep cervical, carcinoma, metastatic,

 thyroid gland X 1 

Lymph node, mandibular + 4 

Lymph node, mesenteric + + 4 

Spleen + + + + + + + + + + + + + + + + 33 

 1 
 

 

 

 

 

 

 

 

 

 

 

 

 

88 Oxazepam, NTP TR 468 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 10,000 ppm 

(Stop-Exposure) (continued) 

Number of Days on Study 

3 

1 

7 

4 

8 

0 

4 

8 

4 

4 

9 

0 

4 

9 

8 

5 

4 

2 

5 

5 

8 

5 

6 

4 

5 

6 

7 

5 

7 

2 

5 

8 

4 

5 

8 

5 

5 

8 

7 

5 

9 

0 

5 

9 

0 

5 

9 

6 

5 

9 

6 

6 

0 

5 

6 

1 

3 

6 

1 

3 

6 

1 

3 

6 

1 

4 

6 

1 

4 

6 

1 

6 

6 

1 

8 

Carcass ID Number 

2 

5 

1 

2 

7 

8 

2 

5 

9 

2 

6 

8 

2 

7 

9 

2 

8 

5 

2 

5 

2 

2 

5 

3 

2 

9 

9 

2 

8 

1 

2 

8 

9 

2 

9 

0 

2 

6 

2 

2 

6 

9 

2 

8 

7 

2 

5 

5 

2 

7 

5 

2 

9 

3 

2 

6 

3 

2 

7 

2 

2 

7 

4 

2 

5 

8 

2 

9 

6 

2 

7 

6 

2 

5 

6 

Integumentary System 

Mammary gland + 

Adenoma 

Carcinoma X 

Skin + + + + 

Fibroma X 

Fibrosarcoma 

Keratoacanthoma X X 

Sebaceous gland, adenoma X 

Musculoskeletal System 

Bone 

Nervous System 

Brain 

Peripheral nerve 

Spinal cord 

+ 

+ 

+ 

Respiratory System 

Lung + 

Special Senses System 

Eye 

Zymbal’s gland 

Carcinoma 

Urinary System 

Kidney 

Urinary bladder 

+ + + + 

+ 

+ + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X X X X X X X X X X X X X 

Lymphoma malignant 

Mesothelioma malignant X 
 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 89 

TABLE A2 

Individual Animal Tumor Pathology of Male Rats in the 2-Year Feed Study of Oxazepam: 10,000 ppm 

(Stop-Exposure) (continued) 

Number of Days on Study 

6 

2 

0 

6 

2 

7 

6 

3 

1 

6 

3 

4 

6 

3 

8 

6 

4 

1 

6 

4 

1 

6 

4 

1 

6 

4 

5 

6 

4 

7 

6 

5 

3 

6 

5 

9 

6 

7 

0 

6 

8 

1 

6 

8 

7 

6 

9 

0 

6 

9 

1 

6 

9 

2 

6 

9 

4 

6 

9 

6 

6 

9 

7 

7 

0 

2 

7 

1 

9 

7 

1 

9 

7 

2 

2 

Carcass ID Number 

2 

9 

4 

2 

9 

5 

2 

9 

7 

2 

9 

8 

2 

6 

5 

2 

6 

0 

2 

6 

1 

2 

8 

3 

2 

6 

4 

2 

9 

2 

2 

8 

0 

3 

0 

0 

2 

8 

4 

2 

6 

7 

2 

8 

2 

2 

8 

8 

2 

7 

7 

2 

7 

0 

2 

5 

7 

2 

7 

3 

2 

6 

6 

2 

9 

1 

2 

5 

4 

2 

7 

1 

2 

8 

6 

Total 

Tissues/ 

Tumors 

Integumentary System 

Mammary gland 

Adenoma 

Carcinoma

Skin 

Fibroma 

Fibrosarcoma 

Keratoacanthoma

Sebaceous gland, adenoma 

+

X

+ + + 

X

X

+

X

 2 

1 

1 

8 

2 

1 

2 

2 

Musculoskeletal System 

Bone + + + + 4 

Nervous System 

Brain 

Peripheral nerve 

Spinal cord 

+

+

+

 2 

2 

2 

Respiratory System 

Lung + + 3 

Special Senses System 

Eye 

Zymbal’s gland 

Carcinoma 

+ 

+

X

+ 2 

1 

1 

Urinary System 

Kidney 

Urinary bladder

+ + + + + + + + + + + + + + + + + + + + + + + 42 

1 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear 

Lymphoma malignant 

Mesothelioma malignant

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X X X X X X X X X X X X X 

X

50 

34 

1 

1 
90 Oxazepam, NTP TR 468 

TABLE A3a 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Feed Study of Oxazepam 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 

Adrenal Medulla: Benign Pheochromocytoma a Overall rate 14/50 (28%) 9/50 (18%) 6/50 (12%) 3/50 (6%) 

Adjusted rateb 44.1% 42.4% 38.8% 8.8% c Terminal rate 3/17 (18%) 2/11 (18%) 1/6 (17%) 0/0 

First incidence (days) 571 557 655 452 

d Life table test P=0.481 P=0.562N P=0.529N P=0.543 

Logistic regression testd P=0.043N P=0.259N P=0.022N P=0.049N 

Cochran-Armitage testd P=0.003N 

d Fisher exact test P=0.171N P=0.039N P=0.003N 

Kidney (Renal Tubule): Adenoma (Single Sections) 

Overall rate 1/50 (2%) 0/50 (0%) 3/50 (6%) 1/50 (2%) 

Adjusted rate 5.6% 0.0% 23.8% 16.7% 

Terminal rate 0/17 (0%) 0/11 (0%) 1/6 (17%) 0/0 e First incidence (days) 723 — 641 634 

Life table test P=0.009 P=0.598N P=0.099 P=0.159 

Logistic regression test P=0.103 P=0.588N P=0.188 P=0.503 

Cochran-Armitage test P=0.399 

Fisher exact test P=0.500N P=0.309 P=0.753N 

Kidney (Renal Tubule): Adenoma (Step Sections) 

Overall rate 1/50 (2%) 1/50 (2%) 4/50 (8%) 5/50 (10%) 

Adjusted rate 5.9% 9.1% 31.3% 19.5% 

Terminal rate 1/17 (6%) 1/11 (9%) 1/6 (17%) 0/0 

First incidence (days) 730 (T) 730 (T) 653 467 

Life table test P<0.001 P=0.663 P=0.027 P=0.008 

Logistic regression test P=0.009 P=0.663 P=0.071 P=0.151 

Cochran-Armitage test P=0.028 

Fisher exact test P=0.753N P=0.181 P=0.102 

Kidney (Renal Tubule): Adenoma (Single and Step Sections) 

Overall rate 2/50 (4%) 1/50 (2%) 7/50 (14%) 6/50 (12%) 

Adjusted rate 11.1% 9.1% 49.7% 32.9% 

Terminal rate 1/17 (6%) 1/11 (9%) 2/6 (33%) 0/0 

First incidence (days) 723 730 (T) 641 467 

Life table test P<0.001 P=0.656N P=0.004 P=0.001 

Logistic regression test P=0.002 P=0.647N P=0.018 P=0.109 

Cochran-Armitage test P=0.027 

Fisher exact test P=0.500N P=0.080 P=0.134 

Liver: Hepatocellular Adenoma 

Overall rate 1/50 (2%) 0/50 (0%) 0/49 (0%) 3/50 (6%) 

Adjusted rate 5.9% 0.0% 0.0% 8.9% 

Terminal rate 1/17 (6%) 0/11 (0%) 0/6 (0%) 0/0 

First incidence (days) 730 (T) — — 451 

Life table test P=0.011 P=0.587N P=0.707N P=0.073 

Logistic regression test P=0.125 P=0.587N P=0.707N P=0.419 

Cochran-Armitage test P=0.072 

Fisher exact test P=0.500N P=0.505N P=0.309 
Oxazepam, NTP TR 468 91 

TABLE A3a
 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 

Liver: Hepatocellular Adenoma or Carcinoma 

Overall rate 2/50 (4%) 0/50 (0%) 0/49 (0%) 3/50 (6%) 

Adjusted rate 8.4% 0.0% 0.0% 8.9% 

Terminal rate 1/17 (6%) 0/11 (0%) 0/6 (0%) 0/0 

First incidence (days) 608 — — 451 

Life table test P=0.047 P=0.325N P=0.368N P=0.144 

Logistic regression test P=0.299 P=0.269N P=0.268N P=0.637 

Cochran-Armitage test P=0.201 

Fisher exact test P=0.247N P=0.253N P=0.500 

Mammary Gland: Fibroadenoma 

Overall rate 4/50 (8%) 5/50 (10%) 4/50 (8%) 2/50 (4%) 

Adjusted rate 18.2% 32.9% 38.9% 7.4% 

Terminal rate 1/17 (6%) 3/11 (27%) 2/6 (33%) 0/0 

First incidence (days) 698 481 655 452 

Life table test P=0.094 P=0.280 P=0.213 P=0.330 

Logistic regression test P=0.575N P=0.336 P=0.384 P=0.592N 

Cochran-Armitage test P=0.200N 

Fisher exact test P=0.500 P=0.643N P=0.339N 

Mammary Gland: Fibroadenoma or Carcinoma 

Overall rate 4/50 (8%) 5/50 (10%) 4/50 (8%) 2/50 (4%) 

Adjusted rate 18.2% 32.9% 38.9% 7.4% 

Terminal rate 1/17 (6%) 3/11 (27%) 2/6 (33%) 0/0 

First incidence (days) 698 481 655 452 

Life table test P=0.094 P=0.280 P=0.213 P=0.330 

Logistic regression test P=0.575N P=0.336 P=0.384 P=0.592N 

Cochran-Armitage test P=0.200N 

Fisher exact test P=0.500 P=0.643N P=0.339N 

Pancreatic Islets: Adenoma or Carcinoma 

Overall rate 3/50 (6%) 0/48 (0%) 0/49 (0%) 0/50 (0%) 

Adjusted rate 9.9% 0.0% 0.0% 0.0% 

Terminal rate 0/17 (0%) 0/11 (0%) 0/6 (0%) 0/0 

First incidence (days) 682 — — — 

Life table test P=0.257N P=0.232N P=0.321N P=0.648N 

Logistic regression test P=0.142N P=0.170N P=0.173N P=0.404N 

Cochran-Armitage test P=0.073N 

Fisher exact test P=0.129N P=0.125N P=0.121N 

Pituitary Gland (Pars Distalis): Adenoma 

Overall rate 17/49 (35%) 12/50 (24%) 10/50 (20%) 2/48 (4%) 

Adjusted rate 61.7% 41.5% 56.7% 10.9% 

Terminal rate 8/17 (47%) 1/11 (9%) 1/6 (17%) 0/0 

First incidence (days) 471 481 600 529 

Life table test P=0.478N P=0.577N P=0.330 P=0.573N 

Logistic regression test P=0.007N P=0.246N P=0.246N P=0.030N 

Cochran-Armitage test P<0.001N 

Fisher exact test P=0.172N P=0.078N P<0.001N 
92 Oxazepam, NTP TR 468 

TABLE A3a
 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 

Preputial Gland: Adenoma 

Overall rate 7/48 (15%) 9/50 (18%) 5/50 (10%) 4/49 (8%) 

Adjusted rate 29.8% 38.8% 30.2% 17.7% 

Terminal rate 3/17 (18%) 3/11 (27%) 1/6 (17%) 0/0 

First incidence (days) 601 523 613 529 

Life table test P=0.142 P=0.178 P=0.371 P=0.069 

Logistic regression test P=0.251N P=0.362 P=0.558N P=0.656N 

Cochran-Armitage test P=0.101N 

Fisher exact test P=0.428 P=0.351N P=0.250N 

Preputial Gland: Adenoma or Carcinoma 

Overall rate 8/48 (17%) 9/50 (18%) 5/50 (10%) 4/49 (8%) 

Adjusted rate 31.5% 38.8% 30.2% 17.7% 

Terminal rate 3/17 (18%) 3/11 (27%) 1/6 (17%) 0/0 

First incidence (days) 541 523 613 529 

Life table test P=0.210 P=0.257 P=0.494 P=0.143 

Logistic regression test P=0.163N P=0.507 P=0.377N P=0.432N 

Cochran-Armitage test P=0.070N 

Fisher exact test P=0.537 P=0.250N P=0.168N 

Skin: Keratoacanthoma 

Overall rate 3/50 (6%) 5/50 (10%) 1/50 (2%) 3/50 (6%) 

Adjusted rate 10.1% 23.5% 5.0% 17.5% 

Terminal rate 0/17 (0%) 1/11 (9%) 0/6 (0%) 0/0 

First incidence (days) 585 524 663 507 

Life table test P=0.199 P=0.210 P=0.547N P=0.121 

Logistic regression test P=0.439N P=0.343 P=0.338N P=0.606 

Cochran-Armitage test P=0.351N 

Fisher exact test P=0.357 P=0.309N P=0.661N 

Skin: Squamous Cell Papilloma or Keratoacanthoma 

Overall rate 5/50 (10%) 5/50 (10%) 2/50 (4%) 3/50 (6%) 

Adjusted rate 14.6% 23.5% 12.9% 17.5% 

Terminal rate 0/17 (0%) 1/11 (9%) 0/6 (0%) 0/0 

First incidence (days) 517 524 663 507 

Life table test P=0.293 P=0.422 P=0.512N P=0.292 

Logistic regression test P=0.268N P=0.616N P=0.222N P=0.411N 

Cochran-Armitage test P=0.200N 

Fisher exact test P=0.630N P=0.218N P=0.357N 

Skin: Malignant Schwannoma 

Overall rate 3/50 (6%) 0/50 (0%) 0/50 (0%) 0/50 (0%) 

Adjusted rate 11.6% 0.0% 0.0% 0.0% 

Terminal rate 1/17 (6%) 0/11 (0%) 0/6 (0%) 0/0 

First incidence (days) 480 — — — 

Life table test P=0.188N P=0.181N P=0.256N P=0.467N 

Logistic regression test P=0.076N P=0.110N P=0.109N P=0.155N 

Cochran-Armitage test P=0.074N 

Fisher exact test P=0.121N P=0.121N P=0.121N 
Oxazepam, NTP TR 468 93 

TABLE A3a
 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 

Skin (Subcutaneous Tissue): Fibroma 

Overall rate 3/50 (6%) 1/50 (2%) 1/50 (2%) 2/50 (4%) 

Adjusted rate 16.2% 2.9% 3.1% 100.0% 

Terminal rate 2/17 (12%) 0/11 (0%) 0/6 (0%) 0/0 

First incidence (days) 711 572 613 585 

Life table test P=0.088 P=0.433N P=0.609N P=0.016 

Logistic regression test P=0.398 P=0.398N P=0.452N P=0.230 

Cochran-Armitage test P=0.512N 

Fisher exact test P=0.309N P=0.309N P=0.500N 

Skin (Subcutaneous Tissue): Fibrosarcoma 

Overall rate 2/50 (4%) 3/50 (6%) 0/50 (0%) 0/50 (0%) 

Adjusted rate 6.3% 10.4% 0.0% 0.0% 

Terminal rate 0/17 (0%) 0/11 (0%) 0/6 (0%) 0/0 

First incidence (days) 491 536 — — 

Life table test P=0.137N P=0.389 P=0.339N P=0.461N 

Logistic regression test P=0.030N P=0.607 P=0.182N P=0.188N 

Cochran-Armitage test P=0.051N 

Fisher exact test P=0.500 P=0.247N P=0.247N 

Skin (Subcutaneous Tissue): Fibrosarcoma or Sarcoma 

Overall rate 3/50 (6%) 3/50 (6%) 0/50 (0%) 0/50 (0%) 

Adjusted rate 11.0% 10.4% 0.0% 0.0% 

Terminal rate 0/17 (0%) 0/11 (0%) 0/6 (0%) 0/0 

First incidence (days) 491 536 — — 

Life table test P=0.107N P=0.533 P=0.252N P=0.434N 

Logistic regression test P=0.020N P=0.608N P=0.107N P=0.149N 

Cochran-Armitage test P=0.027N 

Fisher exact test P=0.661N P=0.121N P=0.121N 

Skin (Subcutaneous Tissue): Fibroma, Fibrosarcoma, or Sarcoma 

Overall rate 5/50 (10%) 4/50 (8%) 1/50 (2%) 2/50 (4%) 

Adjusted rate 21.5% 12.9% 3.1% 100.0% 

Terminal rate 2/17 (12%) 0/11 (0%) 0/6 (0%) 0/0 

First incidence (days) 491 536 613 585 

Life table test P=0.541 P=0.594 P=0.318N P=0.231 

Logistic regression test P=0.172N P=0.489N P=0.124N P=0.670N 

Cochran-Armitage test P=0.107N 

Fisher exact test P=0.500N P=0.102N P=0.218N 

Testes: Adenoma 

Overall rate 45/50 (90%) 48/50 (96%) 49/50 (98%) 47/50 (94%) 

Adjusted rate 100.0% 100.0% 100.0% 100.0% 

Terminal rate 17/17 (100%) 11/11 (100%) 6/6 (100%) 0/0 

First incidence (days) 517 386 381 422 

Life table test P<0.001 P=0.014 P<0.001 P<0.001 

Logistic regression test P=0.011 P=0.054 P=0.012 P<0.001 

Cochran-Armitage test P=0.354 

Fisher exact test P=0.218 P=0.102 P=0.357 
94 Oxazepam, NTP TR 468 

TABLE A3a
 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 

Thyroid Gland (C-cell): Adenoma 

Overall rate 10/50 (20%) 5/49 (10%) 6/50 (12%) 2/50 (4%) 

Adjusted rate 35.5% 34.6% 31.7% 8.6% 

Terminal rate 3/17 (18%) 3/11 (27%) 0/6 (0%) 0/0 

First incidence (days) 571 614 558 452 

Life table test P=0.299 P=0.400N P=0.444 P=0.564 

Logistic regression test P=0.210N P=0.312N P=0.351N P=0.145N 

Cochran-Armitage test P=0.023N 

Fisher exact test P=0.140N P=0.207N P=0.014N 

Thyroid Gland (Follicular Cell): Carcinoma 

Overall rate 3/50 (6%) 3/49 (6%) 3/50 (6%) 4/50 (8%) 

Adjusted rate 12.5% 16.3% 12.6% 13.4% 

Terminal rate 1/17 (6%) 1/11 (9%) 0/6 (0%) 0/0 

First incidence (days) 688 614 424 442 

Life table test P=0.021 P=0.456 P=0.339 P=0.057 

Logistic regression test P=0.395 P=0.546 P=0.656 P=0.516 

Cochran-Armitage test P=0.405 

Fisher exact test P=0.651 P=0.661N P=0.500 

Thyroid Gland (Follicular Cell): Adenoma or Carcinoma 

Overall rate 4/50 (8%) 3/49 (6%) 4/50 (8%) 6/50 (12%) 

Adjusted rate 14.6% 16.3% 15.4% 59.2% 

Terminal rate 1/17 (6%) 1/11 (9%) 0/6 (0%) 0/0 

First incidence (days) 554 614 424 442 

Life table test P=0.002 P=0.603 P=0.354 P=0.010 

Logistic regression test P=0.188 P=0.582N P=0.617N P=0.318 

Cochran-Armitage test P=0.218 

Fisher exact test P=0.511N P=0.643N P=0.370 

All Organs: Mononuclear Cell Leukemia 

Overall rate 27/50 (54%) 36/50 (72%) 33/50 (66%) 19/50 (38%) 

Adjusted rate 72.4% 91.4% 86.0% 100.0% 

Terminal rate 8/17 (47%) 8/11 (73%) 3/6 (50%) 0/0 

First incidence (days) 498 426 381 442 

Life table test P<0.001 P=0.005 P=0.002 P<0.001 

Logistic regression test P=0.049N P=0.020 P=0.187 P=0.459N 

Cochran-Armitage test P=0.009N 

Fisher exact test P=0.048 P=0.154 P=0.080N 

All Organs: Benign Neoplasms 

Overall rate 47/50 (94%) 50/50 (100%) 50/50 (100%) 47/50 (94%) 

Adjusted rate 100.0% 100.0% 100.0% 100.0% 

Terminal rate 17/17 (100%) 11/11 (100%) 6/6 (100%) 0/0 

First incidence (days) 471 386 381 422 

Life table test P<0.001 P=0.014 P<0.001 P<0.001 

Logistic regression test P=0.040 P=0.011 P=0.014 P=0.001 

Cochran-Armitage test P=0.370N 

Fisher exact test P=0.121 P=0.121 P=0.661N 
95 

c 

Oxazepam, NTP TR 468 

TABLE A3a
 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 

All Organs: Malignant Neoplasms 

Overall rate 38/50 (76%) 43/50 (86%) 40/50 (80%) 25/50 (50%) 

Adjusted rate 85.6% 93.5% 96.5% 100.0% 

Terminal rate 11/17 (65%) 8/11 (73%) 5/6 (83%) 0/0 

First incidence (days) 480 426 381 237 

Life table test P<0.001 P=0.016 P=0.003 P<0.001 

Logistic regression test P<0.001N P=0.083 P=0.477 P=0.025N 

Cochran-Armitage test P<0.001N 

Fisher exact test P=0.154 P=0.405 P=0.006N 

All Organs: Benign or Malignant Neoplasms 

Overall rate 50/50 (100%) 50/50 (100%) 50/50 (100%) 48/50 (96%) 

Adjusted rate 100.0% 100.0% 100.0% 100.0% 

Terminal rate 17/17 (100%) 11/11 (100%) 6/6 (100%) 0/0 

First incidence (days) 471 386 381 237 

Life table test 

Logistic regression test 

P<0.001 

—f P=0.035 — 

P=0.001 

— 

P<0.001 

— 

Cochran-Armitage test P=0.043N 

Fisher exact test P=1.000N P=1.000N P=0.247N 

(T) Terminal sacrifice a Number of neoplasm-bearing animals/number of animals examined. Denominator is number of animals examined microscopically for adrenal gland, 

kidney, liver, pancreatic islets, pituitary gland, preputial gland, testes, and thyroid gland; for other tissues, denominator is number of animals necropsied. b Kaplan-Meier estimated neoplasm incidence at the end of the study after adjustment for intercurrent mortality 

Observed incidence at terminal kill 

d	 Beneath the control incidence are the P values associated with the trend test. Beneath the exposed group incidence are the P values corresponding to 

pairwise comparisons between the controls and that exposed group. The life table test regards neoplasms in animals dying prior to terminal kill as being 

(directly or indirectly) the cause of death. The logistic regression test regards these lesions as nonfatal. The Cochran-Armitage and Fisher exact tests 

compare directly the overall incidence rates. For all tests, a negative trend or a lower incidence in an exposed group is indicated by N. e Not applicable; no neoplasms in animal group f Value of statistic cannot be computed. 
96 Oxazepam, NTP TR 468 

TABLE A3b 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Stop-Exposure Feed Study of Oxazepam 

0 ppm 10,000 ppm 

Adrenal Medulla: Benign Pheochromocytoma 

Overall ratea 14/50 (28%) 0/1 (0%)d 

Adjusted rateb 44.1% c Terminal rate 3/17 (18%) 

First incidence (days) 571 

Adrenal Medulla: Benign or Malignant Pheochromocytoma 

Overall rate 14/50 (28%) 1/1 (100%)d
 

Adjusted rate 44.1%
 

Terminal rate 3/17 (18%)
 

First incidence (days) 571
 

Kidney (Renal Tubule): Adenoma (Step Sections) 

Overall rate 1/50 (2%) 6/45 (13%) 

Adjusted rate 5.9% 39.1% 

Terminal rate 1/17 (6%) 0/0 

First incidence (days) 730 (T) 613 

Life table teste P=0.001 e Logistic regression test P=0.024 

Fisher exact teste P=0.041 

Kidney (Renal Tubule): Adenoma (Single and Step Sections) 

Overall rate 2/50 (4%) 6/45 (13%) 

Adjusted rate 11.1% 39.1% 

Terminal rate 1/17 (6%) 0/0 

First incidence (days) 723 613 

Life table test P=0.001 

Logistic regression test P=0.046 

Fisher exact test P=0.103 

Mammary Gland: Fibroadenoma 

Overall rate 4/50 (8%) 0/50 (0%) 

Adjusted rate 18.2% 0.0% 

Terminal rate 1/17 (6%) 0/0 

First incidence (days) 698 —f 

Life table test P=0.537N 

Logistic regression test P=0.214N 

Fisher exact test P=0.059N 

Mammary Gland: Fibroadenoma or Adenoma 

Overall rate 4/50 (8%) 1/50 (2%) 

Adjusted rate 18.2% 10.0% 

Terminal rate 1/17 (6%) 0/0 

First incidence (days) 698 690 

Life table test P=0.608 

Logistic regression test P=0.515N 

Fisher exact test P=0.181N 

Mammary Gland: Fibroadenoma, Adenoma, or Carcinoma 

Overall rate 4/50 (8%) 2/50 (4%) 

Adjusted rate 18.2% 13.1% 

Terminal rate 1/17 (6%) 0/0 

First incidence (days) 698 614 

Life table test P=0.345 

Logistic regression test P=0.614N 

Fisher exact test P=0.339N 
Oxazepam, NTP TR 468 97 

TABLE A3b
 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Stop-Exposure Feed Study of Oxazepam (continued)
 

0 ppm 10,000 ppm 

Pancreatic Islets: Adenoma or Carcinoma 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

3/50 (6%) 

9.9% 

0/17 (0%) 

682 

0/0d 

Pituitary Gland (Pars Distalis): Adenoma 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

17/49 (35%) 

61.7% 

8/17 (47%) 

471 

5/5 (100%)d 

Preputial Gland: Adenoma 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

7/48 (15%) 

29.8% 

3/17 (18%) 

601 

10/14 (71%)d 

Preputial Gland: Adenoma or Carcinoma 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

8/48 (17%) 

31.5% 

3/17 (18%) 

541 

10/14 (71%)d 

Skin: Keratoacanthoma 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

Life table test 

3/50 (6%) 

10.1% 

0/17 (0%) 

585 

2/50 (4%) 

4.8% 

0/0 

542 

P=0.645 

Logistic regression test 

Fisher exact test 

P=0.449N 

P=0.500N 

Skin: Squamous Cell Papilloma or Keratoacanthoma 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

Life table test 

5/50 (10%) 

14.6% 

0/17 (0%) 

517 

2/50 (4%) 

4.8% 

0/0 

542 

P=0.458N 

Logistic regression test 

Fisher exact test 

P=0.157N 

P=0.218N 

Skin: Malignant Schwannoma 

Overall rate 

Adjusted rate 

Terminal rate 

First incidence (days) 

Life table test 

3/50 (6%) 

11.6% 

1/17 (6%) 

480 

0/50 (0%) 

0.0% 

0/0 

— 

P=0.377N 

Logistic regression test 

Fisher exact test 

P=0.107N 

P=0.121N 
98 Oxazepam, NTP TR 468 

TABLE A3b
 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Stop-Exposure Feed Study of Oxazepam (continued)
 

0 ppm 10,000 ppm 

Skin (Subcutaneous Tissue): Fibroma 

Overall rate 3/50 (6%) 2/50 (4%) 

Adjusted rate 16.2% 34.8% 

Terminal rate 2/17 (12%) 0/0 

First incidence (days) 711 558 

Life table test P=0.154 

Logistic regression test P=0.629 

Fisher exact test P=0.500N 

Skin (Subcutaneous Tissue): Fibrosarcoma or Sarcoma 

Overall rate 3/50 (6%) 1/50 (2%) 

Adjusted rate 11.0% 20.0% 

Terminal rate 0/17 (0%) 0/0 

First incidence (days) 491 697 

Life table test P=0.712 

Logistic regression test P=0.323N 

Fisher exact test P=0.309N 

Skin (Subcutaneous Tissue): Fibroma, Fibrosarcoma, or Sarcoma 

Overall rate 5/50 (10%) 3/50 (6%) 

Adjusted rate 21.5% 47.9% 

Terminal rate 2/17 (12%) 0/0 

First incidence (days) 491 558 

Life table test P=0.187 

Logistic regression test P=0.492N 

Fisher exact test P=0.357N 

Testes: Adenoma 

Overall rate 45/50 (90%) 48/48 (100%) 

Adjusted rate 100.0% 100.0% 

Terminal rate 17/17 (100%) 0/0 

First incidence rate 517 480 

Life table test P<0.001 

Logistic regression test P=0.014 

Fisher exact test P=0.031 

Thyroid Gland (C-cell): Adenoma 

Overall rate 10/50 (20%) 1/50 (2%) 

Adjusted rate 35.5% 9.1% 

Terminal rate 3/17 (18%) 0/0 

First incidence (days) 571 687 

Life table test P=0.320N 

Logistic regression test P=0.030N 

Fisher exact test P=0.004N 

Thyroid Gland (C-cell): Adenoma or Carcinoma 

Overall rate 10/50 (20%) 2/50 (4%) 

Adjusted rate 35.5% 13.2% 

Terminal rate 3/17 (18%) 0/0 

First incidence (days) 571 634 

Life table test P=0.516N 

Logistic regression test P=0.068N 

Fisher exact test P=0.014N 
Oxazepam, NTP TR 468 99 

TABLE A3b
 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Stop-Exposure Feed Study of Oxazepam (continued)
 

0 ppm 10,000 ppm 

Thyroid Gland (Follicular Cell): Carcinoma 

Overall rate 3/50 (6%) 1/50 (2%) 

Adjusted rate 12.5% 4.8% 

Terminal rate 1/17 (6%) 0/0 

First incidence (days) 688 638 

Life table test P=0.660 

Logistic regression test P=0.513N 

Fisher exact test P=0.309N 

Thyroid Gland (Follicular Cell): Adenoma or Carcinoma 

Overall rate 4/50 (8%) 2/50 (4%) 

Adjusted rate 14.6% 9.5% 

Terminal rate 1/17 (6%) 0/0 

First incidence (days) 554 638 

Life table test P=0.573 

Logistic regression test P=0.400N 

Fisher exact test P=0.339N 

All Organs: Mononuclear Cell Leukemia 

Overall rate 27/50 (54%) 34/50 (68%) 

Adjusted rate 72.4% 100.0% 

Terminal rate 8/17 (47%) 0/0 

First incidence (days) 498 480 

Life table test P<0.001 

Logistic regression test P=0.075 

Fisher exact test P=0.109 

All Organs: Benign Neoplasms 

Overall rate 47/50 (94%) 48/50 (96%) 

Adjusted rate 100.0% 100.0% 

Terminal rate 17/17 (100%) 0/0 

First incidence (days) 471 480 

Life table test P<0.001 

Logistic regression test P=0.331 

Fisher exact test P=0.500 

All Organs: Malignant Neoplasms 

Overall rate 38/50 (76%) 35/50 (70%) 

Adjusted rate 85.6% 100.0% 

Terminal rate 11/17 (65%) 0/0 

First incidence (days) 480 480 

Life table test P<0.001 

Logistic regression test P=0.363N 

Fisher exact test P=0.326N 
100 

c 

Oxazepam, NTP TR 468 

TABLE A3b
 

Statistical Analysis of Primary Neoplasms in Male Rats in the 2-Year Stop-Exposure Feed Study of Oxazepam (continued)
 

0 ppm	 10,000 ppm 

All Organs: Benign or Malignant Neoplasms 

Overall rate 50/50 (100%) 48/50 (96%) 

Adjusted rate 100.0% 100.0% 

Terminal rate 17/17 (100%) 0/0 

First incidence (days) 471 480 

Life table test P<0.001 

Logistic regression test P=0.423N 

Fisher exact test P=0.247N 

a Number of neoplasm-bearing animals/number of animals examined. Denominator is number of animals examined microscopically for adrenal gland, 

kidney, pancreatic islets, pituitary gland, preputial gland, testes, and thyroid gland; for other tissues, denominator is number of animals necropsied. b	 Kaplan-Meier estimated neoplasm incidence at the end of the study after adjustment for intercurrent mortality 

Observed incidence at terminal kill 

d	 Tissue was examined microscopically only when it was observed to be abnormal at necropsy; thus, statistical comparisons with the controls are not 

appropriate. e Beneath the exposed group incidence are the P values corresponding to pairwise comparisons between the controls and the exposed group. The life 

table test regards neoplasms in animals dying prior to terminal kill as being (directly or indirectly) the cause of death. The logistic regression test 

regards these lesions as nonfatal. The Fisher exact test compares directly the overall incidence rates. For all tests, a lower incidence in the exposed 

group is indicated by N. f	 Not applicable; no neoplasms in animal group 
Oxazepam, NTP TR 468 101 

TABLE A4a 

Historical Incidence of Renal Tubule Adenoma in Untreated Male F344/N Ratsa 

Study Incidence in Controls 

Historical Incidence at Battelle Columbus Laboratories 

4,4'-Thiobis(6-t-Butyl-m-Cresol) 0/50 

5,5-Diphenylhydantoin 0/50 

Ethylene Thiourea 0/50 

Polybrominated Biphenyls (Firemaster FF-1®) 0/50 

Manganese (II) Sulfate Monohydrate 1/52 

Triamterene 1/50 

Tricresyl Phosphate 0/51 

Overall Historical Incidence 

Total 9/1,301 (0.7%) 

Standard deviation 1.5% 

Range 0%-6% 

a Data as of 12 May 1995 

TABLE A4b 

Historical Incidence of Benign Adrenal Medulla Pheochromocytoma in Untreated Male F344/N Ratsa 

Study Incidence in Controls 

Historical Incidence at Battelle Columbus Laboratories 

4,4'-Thiobis(6-t-Butyl-m-Cresol) 14/50 

5,5-Diphenylhydantoin 19/50 

Ethylene Thiourea 22/50 

Polybrominated Biphenyls (Firemaster FF-1®) 12/49 

Manganese (II) Sulfate Monohydrate 14/52 

Triamterene 9/50 

Tricresyl Phosphate 5/50 

Overall Historical Incidence 

Total 396/1,283 (30.9%) 

Standard deviation 12.1% 

Range 10%-63% 

a Data as of 12 May 1995 
102 Oxazepam, NTP TR 468 

TABLE A4c 

Historical Incidence of Pituitary Gland (Pars Distalis) Adenoma in Untreated Male F344/N Ratsa 

Study Incidence in Controls 

Historical Incidence at Battelle Columbus Laboratories 

4,4'-Thiobis(6-t-Butyl-m-Cresol) 14/50 

5,5-Diphenylhydantoin 14/50 

Ethylene Thiourea 19/50 

Polybrominated Biphenyls (Firemaster FF-1®) 13/50 

Manganese (II) Sulfate Monohydrate 13/52 

Triamterene 8/50 

Tricresyl Phosphate 8/51 

Overall Historical Incidence 

Total 377/1,284 (29.4%) 

Standard deviation 10.6% 

Range 14%-60% 

a Data as of 12 May 1995 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 103 

TABLE A5 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Feed Study of Oxazepama 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Disposition Summary 

Animals initially in study 50 50 50 50 50 

Early deaths

 Moribund 25 27 33 43 39

 Natural deaths 8 12 11 7 11 

Survivors

 Terminal sacrifice 17 11 6 

Animals examined microscopically 50 50 50 50 50 

Alimentary System 

Intestine large, colon (50) (47) (50) (50) (1) 

Parasite metazoan 4 (9%) 2 (4%) 

Serosa, inflammation, chronic 1 (100%) 

Intestine large, rectum (50) (48) (49) (50) (1) 

Congestion 1 (2%) 

Edema 1 (2%) 

Parasite metazoan 1 (2%) 2 (4%) 

Serosa, inflammation, chronic 1 (100%) 

Intestine large, cecum (50) (48) (49) (50) (1) 

Congestion 1 (2%) 

Edema 1 (2%) 

Serosa, inflammation, chronic 1 (100%) 

Intestine small, duodenum (50) (48) (49) (50) (44) 

Erosion 4 (8%) 3 (6%) 9 (18%) 16 (32%) 1 (2%) 

Inflammation, chronic active 1 (2%) 

Mineralization 6 (14%) 

Ulcer 1 (2%) 2 (4%) 2 (4%) 

Intestine small, ileum (50) (47) (46) (49) 

Ulcer 1 (2%) 

Liver (50) (50) (49) (50) (50) 

Angiectasis 1 (2%) 1 (2%) 

Basophilic focus 21 (42%) 11 (22%) 4 (8%) 2 (4%) 13 (26%) 

Clear cell focus 2 (4%) 4 (8%) 

Degeneration, cystic 3 (6%) 1 (2%) 1 (2%) 

Degeneration, fatty 1 (2%) 1 (2%) 

Eosinophilic focus 8 (16%) 5 (10%) 5 (10%) 6 (12%) 2 (4%) 

Hepatodiaphragmatic nodule 1 (2%) 3 (6%) 1 (2%) 2 (4%) 3 (6%) 

Mixed cell focus 2 (4%) 4 (8%) 2 (4%) 1 (2%) 1 (2%) 

Necrosis, focal 1 (2%) 5 (10%) 4 (8%) 

Bile duct, hyperplasia 1 (2%) 1 (2%) 

Centrilobular, congestion 1 (2%) 

Centrilobular, degeneration 1 (2%) 1 (2%) 1 (2%) 

Centrilobular, necrosis 3 (6%) 1 (2%) 4 (8%) 3 (6%) 2 (4%) 

Hepatocyte, centrilobular, hypertrophy 1 (2%) 8 (16%) 14 (28%) 

Serosa, fibrosis 1 (2%) 

Serosa, inflammation, chronic 1 (2%) 

Mesentery (7) (6) (4) (4) (5) 

Accessory spleen 1 (14%) 1 (17%) 1 (20%) 

Necrosis, acute, focal 1 (17%) 

Fat, necrosis 6 (86%) 3 (50%) 3 (75%) 4 (100%) 4 (80%) 

Pancreas (50) (48) (49) (50) 

Acinus, atrophy 17 (34%) 10 (21%) 14 (29%) 1 (2%) 

Acinus, hyperplasia 1 (2%) 

Artery, inflammation, granulomatous 1 (2%) 1 (2%) 

a Number of animals examined microscopically at the site and the number of animals with lesion 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

104 Oxazepam, NTP TR 468 

TABLE A5
 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Alimentary System (continued) 

Salivary glands (50) (49) (50) (50) 

Parotid gland, degeneration 1 (2%) 

Parotid gland, hyperplasia, focal 1 (2%) 

Stomach, forestomach (50) (48) (50) (50) (49) 

Erosion 1 (2%) 1 (2%) 2 (4%) 1 (2%) 

Hyperplasia 1 (2%) 

Inflammation, chronic 1 (2%) 

Inflammation, chronic active 6 (12%) 8 (17%) 22 (44%) 15 (30%) 10 (20%) 

Mineralization 1 (2%) 4 (8%) 

Ulcer 9 (18%) 12 (25%) 20 (40%) 10 (20%) 7 (14%) 

Epithelium, hyperplasia 5 (10%) 8 (17%) 25 (50%) 16 (32%) 15 (31%) 

Serosa, inflammation 3 (6%) 

Stomach, glandular (50) (48) (50) (50) (47) 

Erosion 5 (10%) 5 (10%) 9 (18%) 4 (8%) 5 (11%) 

Inflammation, chronic active 2 (4%) 

Mineralization 3 (6%) 1 (2%) 4 (8%) 16 (34%) 

Ulcer 2 (4%) 7 (15%) 7 (14%) 4 (8%) 4 (9%) 

Serosa, inflammation 2 (4%) 

Cardiovascular System 

Blood vessel (49) (50) (50) (50) 

Aorta, mineralization 1 (2%) 3 (6%) 

Aorta, thrombosis 1 (2%) 

Heart (50) (50) (50) (50) (7) 

Atrium, thrombosis 7 (14%) 1 (2%) 5 (71%) 

Myocardium, degeneration 46 (92%) 40 (80%) 43 (86%) 37 (74%) 1 (14%) 

Myocardium, mineralization 1 (2%) 2 (4%) 1 (2%) 4 (57%) 

Endocrine System 

Adrenal cortex (50) (50) (50) (50) 

Degeneration, cystic 1 (2%) 

Hyperplasia, focal 5 (10%) 10 (20%) 8 (16%) 6 (12%) 

Hypertrophy, focal 1 (2%) 

Necrosis, focal 1 (2%) 

Adrenal medulla (50) (50) (50) (50) (1) 

Hyperplasia 9 (18%) 9 (18%) 15 (30%) 16 (32%) 

Islets, pancreatic (50) (48) (49) (50) 

Hyperplasia 3 (6%) 2 (4%) 1 (2%) 

Parathyroid gland (39) (41) (46) (40) (13) 

Hyperplasia 3 (8%) 6 (15%) 9 (20%) 16 (40%) 13 (100%) 

Pituitary gland (49) (50) (50) (48) (5) 

Cyst 1 (2%) 

Degeneration, cystic 1 (2%) 

Pars distalis, cyst 2 (4%) 1 (2%) 

Pars distalis, hyperplasia 9 (18%) 5 (10%) 3 (6%) 1 (2%) 

Pars distalis, thrombosis 1 (2%) 

Pars nervosa, gliosis, focal 1 (2%) 

Thyroid gland (50) (49) (50) (50) (50) 

Mineralization 1 (2%) 

C-cell, hyperplasia 33 (66%) 36 (73%) 38 (76%) 38 (76%) 41 (82%) 

Follicle, cyst 4 (8%) 2 (4%) 4 (8%) 6 (12%) 9 (18%) 

Follicle, hyperplasia 1 (2%) 

Follicle, ultimobranchial cyst 1 (2%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 105 

TABLE A5
 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

General Body System 

Peritoneum (2) (1) (1) (2) (1) 

Inflammation, chronic 1 (50%) 

Genital System 

Epididymis (50) (49) (50) (50) (1) 

Cyst 1 (2%) 

Inflammation, chronic 1 (2%) 

Preputial gland (48) (50) (50) (49) (14) 

Cyst 1 (2%) 

Hyperplasia 1 (2%) 

Inflammation, chronic active 2 (4%) 1 (2%) 

Inflammation, suppurative 1 (2%) 1 (2%) 4 (8%) 3 (21%) 

Duct, cyst 1 (2%) 4 (8%) 4 (8%) 3 (6%) 1 (7%) 

Prostate (50) (50) (50) (50) 

Inflammation, chronic active 1 (2%) 

Inflammation, suppurative 1 (2%) 

Seminal vesicle (50) (50) (50) (50) (1) 

Atrophy 1 (100%) 

Cyst 1 (2%) 1 (2%) 

Fibrosis 1 (2%) 

Hyperplasia 1 (2%) 

Inflammation, chronic 1 (2%) 

Inflammation, suppurative 1 (2%) 

Testes (50) (50) (50) (50) (48) 

Germinal epithelium, atrophy 2 (4%) 2 (4%) 1 (2%) 1 (2%) 

Hematopoietic System 

Bone marrow (50) (50) (50) (50) 

Necrosis 1 (2%) 

Thrombosis 1 (2%) 

Lymph node (5) (8) (8) (1) (9) 

Renal, ectasia 1 (13%) 

Renal, pigmentation 1 (11%) 

Lymph node, mesenteric (49) (49) (50) (47) (4) 

Congestion 1 (2%) 

Inflammation, chronic active 1 (2%) 

Spleen (50) (50) (50) (50) (33) 

Fibrosis 7 (14%) 3 (6%) 3 (6%) 4 (8%) 8 (24%) 

Hematopoietic cell proliferation 6 (12%) 1 (2%) 3 (6%) 5 (10%) 

Necrosis 1 (2%) 1 (2%) 

Pigmentation, hemosiderin 1 (2%) 3 (6%) 2 (4%) 

Lymphoid follicle, atrophy 1 (2%) 1 (2%) 

Red pulp, congestion 1 (2%) 1 (2%) 2 (4%) 

Thymus (49) (47) (49) (47) 

Ectopic parathyroid gland 2 (4%) 

Ectopic thyroid 1 (2%) 

Integumentary System 

Mammary gland (50) (44) (48) (48) (2) 

Hyperplasia, cystic 3 (6%) 

Inflammation, suppurative 1 (2%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

106 Oxazepam, NTP TR 468 

TABLE A5
 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Integumentary System (continued) 

Skin (50) (49) (49) (50) (8) 

Ulcer 2 (4%) 

Epidermis, cyst 1 (2%) 

Epidermis, inflammation, suppurative 1 (13%) 

Hair follicle, cyst 1 (2%) 

Musculoskeletal System 

Bone (50) (50) (50) (50) (4) 

Fibrosis 1 (25%) 

Fibrous osteodystrophy 1 (2%) 6 (12%) 8 (16%) 3 (75%) 

Hyperostosis 3 (6%) 1 (2%) 

Nervous System 

Brain (50) (50) (50) (50) (2) 

Hydrocephalus 6 (12%) 2 (4%) 1 (2%) 

Necrosis, focal 1 (2%) 

Hypothalamus, degeneration 1 (2%) 

Medulla, gliosis, focal 1 (2%) 

Respiratory System 

Lung (50) (50) (50) (50) (3) 

Fibrosis 1 (2%) 

Hematopoietic cell proliferation 1 (2%) 

Hemorrhage 1 (2%) 

Inflammation, acute, focal 1 (2%) 

Inflammation, chronic, focal 1 (2%) 

Inflammation, granulomatous 1 (2%) 2 (4%) 3 (6%) 

Metaplasia, squamous 1 (2%) 

Alveolar epithelium, hyperplasia 1 (2%) 1 (2%) 1 (2%) 

Interstitium, inflammation, acute 1 (2%) 

Interstitium, inflammation, chronic 2 (4%) 3 (6%) 

Interstitium, inflammation, chronic,

 focal 1 (2%) 

Interstitium, mineralization 1 (2%) 1 (2%) 

Mediastinum, inflammation, chronic 1 (2%) 

Vein, thrombosis 1 (2%) 

Nose (50) (50) (50) (50) 

Inflammation, suppurative 13 (26%) 14 (28%) 9 (18%) 7 (14%) 

Special Senses System 

Eye (2) (3) (2) (1) (2) 

Cataract 1 (33%) 

Inflammation, suppurative 1 (100%) 

Anterior chamber, inflammation, acute 1 (33%) 1 (50%) 

Anterior chamber, inflammation,

 suppurative 1 (50%) 

Lens, cataract 2 (100%) 1 (33%) 1 (50%) 1 (50%) 
 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 107 

TABLE A5
 

Summary of the Incidence of Nonneoplastic Lesions in Male Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Urinary System 

Kidney (50) (50) (50) (50) (42) 

Amyloid deposition 1 (2%) 

Fibrosis, focal 1 (2%) 

Infarct 1 (2%) 

Nephropathy 49 (98%) 44 (88%) 49 (98%) 50 (100%) 42 (100%) 

Renal tubule, cyst 1 (2%) 1 (2%) 6 (12%) 8 (16%) 3 (7%) 

Renal tubule, hyperplasia 1 (2%) 3 (6%) 1 (2%) 

Renal tubule, pigmentation, lipofuscin 1 (2%) 

Urinary bladder (50) (50) (50) (50) (1) 

Hemorrhage 1 (2%) 

Ulcer 1 (100%) 

Transitional epithelium, hyperplasia 1 (2%) 
108 Oxazepam, NTP TR 468
 
 109 

APPENDIX B 

SUMMARY OF LESIONS IN FEMALE RATS 

IN THE 2-YEAR FEED STUDY 

OF OXAZEPAM 

TABLE B1 

TABLE B2 

TABLE B3a 

TABLE B3b 

TABLE B4a 

TABLE B4b 

TABLE B5 

Summary of the Incidence of Neoplasms in Female Rats 

in the 2-Year Feed Study of Oxazepam .................................. 

Individual Animal Tumor Pathology of Female Rats 

in the 2-Year Feed Study of Oxazepam .................................. 

Statistical Analysis of Primary Neoplasms in Female Rats 

in the 2-Year Feed Study of Oxazepam .................................. 

Statistical Analysis of Primary Neoplasms in Female Rats 

in the 2-Year Stop-Exposure Feed Study of Oxazepam ........................ 

Historical Incidence of Mammary Gland Neoplasms 

in Untreated Female F344/N Rats ...................................... 

Historical Incidence of Pituitary Gland (Pars Distalis) Neoplasms 

in Untreated Female F344/N Rats ...................................... 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats 

in the 2-Year Feed Study of Oxazepam .................................. 

111 

114 

134 

139 

142 

142 

143 
110 Oxazepam, NTP TR 468
 
Oxazepam, NTP TR 468 111 

TABLE B1 

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Feed Study of Oxazepama 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Disposition Summary 

Animals initially in study 50 50 50 50 50 

Early deaths

 Accidental death 1

 Moribund 11 18 18 16 19

 Natural deaths 6 6 12 3 6 

Survivors

 Terminal sacrifice 32 26 20 31 25 

Animals examined microscopically 50 50 50 50 50 

Alimentary System 

Intestine large, colon (50) (48) (49) (50) 

Polyp adenomatous 1 (2%) 

Liver (50) (50) (50) (50) (49) 

Histiocytic sarcoma, metastatic, skin 1 (2%) 

Mesentery (10) (9) (4) (6) (13) 

Pancreas (50) (50) (49) (49) 

Acinus, adenoma 1 (2%) 

Salivary glands (50) (50) (48) (49) (1) 

Myoepithelioma 1 (100%) 

Stomach, forestomach (50) (50) (50) (50) (50) 

Tongue (1) 

Squamous cell carcinoma 1 (100%) 

Cardiovascular System 

None 

Endocrine System 

Adrenal cortex (50) (50) (50) (50) (2) 

Adenoma 1 (2%) 1 (2%) 1 (50%) 

Adrenal medulla (50) (50) (50) (50) 

Pheochromocytoma malignant 1 (2%) 

Pheochromocytoma complex 1 (2%) 

Pheochromocytoma benign 1 (2%) 3 (6%) 1 (2%) 

Islets, pancreatic (50) (50) (49) (49) 

Adenoma 1 (2%) 

Parathyroid gland (42) (38) (38) (33) 

Adenoma 1 (3%) 

Pituitary gland (50) (50) (50) (50) (35) 

Pars distalis, adenoma 30 (60%) 28 (56%) 20 (40%) 12 (24%) 23 (66%) 

Pars distalis, adenoma, multiple 1 (2%) 1 (2%) 

Pars distalis, carcinoma 1 (2%) 

Thyroid gland (50) (50) (48) (49) (50) 

Bilateral, C-cell, adenoma 2 (4%) 

C-cell, adenoma 6 (12%) 3 (6%) 6 (13%) 2 (4%) 2 (4%) 

C-cell, carcinoma 1 (2%) 1 (2%) 1 (2%) 

Follicular cell, adenoma 1 (2%) 2 (4%) 

Follicular cell, carcinoma 1 (2%) 3 (6%) 1 (2%) 
112 Oxazepam, NTP TR 468 

TABLE B1
 

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

General Body System 

None 

Genital System 

Clitoral gland (49) (50) (50) (50) (11) 

Adenoma 6 (12%) 3 (6%) 3 (6%) 4 (8%) 7 (64%) 

Carcinoma 1 (2%) 1 (2%) 

Bilateral, adenoma 1 (2%) 

Ovary (50) (50) (50) (50) (4) 

Granulosa cell tumor benign 1 (2%) 

Tubulostromal adenoma 1 (2%) 

Uterus (50) (50) (50) (50) (5) 

Polyp stromal 2 (4%) 4 (8%) 3 (6%) 4 (8%) 

Sarcoma stromal 1 (2%) 1 (2%) 1 (20%) 

Hematopoietic System 

Lymph node (4) (2) (9) (3) (4) 

Deep cervical, carcinoma, metastatic,

 thyroid gland 1 (25%) 

Renal, pheochromocytoma malignant,

 metastatic, adrenal medulla 1 (25%) 

Lymph node, mandibular (50) (48) (48) (49) (3) 

Squamous cell carcinoma,

 metastatic, skin 1 (33%) 

Lymph node, mesenteric (50) (50) (50) (49) (2) 

Spleen (50) (50) (50) (49) (12) 

Thymus (50) (48) (46) (47) 

Integumentary System 

Mammary gland (49) (49) (49) (50) (23) 

Adenoma 1 (2%) 2 (4%) 

Carcinoma 2 (4%) 3 (6%) 

Carcinoma, multiple 1 (4%) 

Fibroadenoma 11 (22%) 14 (29%) 8 (16%) 12 (24%) 17 (74%) 

Fibroadenoma, multiple 14 (29%) 5 (10%) 1 (2%) 1 (2%) 6 (26%) 

Skin (50) (50) (50) (50) (6) 

Basal cell carcinoma 1 (2%) 

Fibroma 1 (2%) 2 (33%) 

Fibrosarcoma 2 (4%) 

Keratoacanthoma 1 (2%) 

Squamous cell carcinoma 1 (17%) 

Trichoepithelioma 1 (2%) 

Sebaceous gland, adenoma 1 (2%) 

Subcutaneous tissue, histiocytic sarcoma 1 (17%) 

Musculoskeletal System 

Bone (50) (50) (50) (50) (1) 

Osteosarcoma 1 (2%) 
113 

c 

Oxazepam, NTP TR 468 

TABLE B1
 

Summary of the Incidence of Neoplasms in Female Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Nervous System 

Brain 

Astrocytoma benign 

Carcinoma, metastatic, pituitary gland 

Oligodendroglioma malignant 

(50) 

1 (2%) 

(50) 

1 (2%) 

(50) 

1 (2%) 

(50) 

Respiratory System 

Lung 

Alveolar/bronchiolar adenoma 

Alveolar/bronchiolar carcinoma 

Carcinoma, metastatic, thyroid gland 

(50) (50) 

1 (2%) 

(49) 

1 (2%) 

(49) 

2 (4%) 

Special Senses System 

Zymbal’s gland 

Carcinoma 

(2) 

2 (100%) 

Urinary System 

Kidney 

Nephroblastoma 

Urinary bladder 

Sarcoma stromal, metastatic, uterus 

(50) 

(48) 

(50) 

1 (2%) 

(49) 

(50) 

(49) 

(50) 

(50) 

1 (2%) 

(1) 

Systemic Lesions 

Multiple organsb 

Histiocytic sarcoma 

Leukemia mononuclear 

(50) 

14 (28%) 

(50) 

19 (38%) 

(50) 

29 (58%) 

(50) 

18 (36%) 

(50) 

1 (2%) 

15 (30%) 

Neoplasm Summary 

Total animals with primary neoplasmsc

 Total primary neoplasms 

Total animals with benign neoplasms 

Total benign neoplasms 

Total animals with malignant neoplasms 

Total malignant neoplasms 

Total animals with metastatic neoplasms 

Total metastatic neoplasms 

49 

101 

43 

77 

21 

24 

2 

2 

49 

93 

39 

65 

26 

28 

45 

80 

30 

45 

34 

35 

2 

2 

38 

67 

26 

44 

22 

23 

1 

1 

43 

80 

38

61 

17

19 

2

2 

a Number of animals examined microscopically at the site and the number of animals with neoplasm b Number of animals with any tissue examined microscopically 

Primary neoplasms: all neoplasms except metastatic neoplasms 
 

 

 

 

 

 

 

 

 

 

 

 

 

114 Oxazepam, NTP TR 468 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 0 ppm 

Number of Days on Study 

2 2 5 5 5 5 5 5 5 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 

2 2 2 2 5 6 7 8 9 1 4 4 9 9 9 0 0 0 2 3 3 3 3 3 3 

3 8 2 9 0 9 1 3 7 3 1 7 0 6 7 0 1 8 9 0 0 0 0 0 0 

Carcass ID Number 

3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

0 2 0 0 4 2 2 5 0 3 0 2 3 1 0 2 2 1 0 0 0 1 1 1 2 

1 2 5 4 1 3 9 0 9 7 8 4 1 5 2 6 8 4 6 3 7 1 2 3 0 

Alimentary System 

Esophagus 

Intestine large, colon 

Polyp adenomatous 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Mesentery 

Pancreas 

Salivary glands 

Stomach, forestomach 

Stomach, glandular 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

A + + + + + + + + + A + A + + A + + + + + + + + + 

A + + + + + + + + + M + + + + A + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Cardiovascular System 

Blood vessel + + + + + + + + + + + + + + + + + + + + + + + + + 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + 

Pheochromocytoma malignant X 

Pheochromocytoma complex X 

Pheochromocytoma benign 

Islets, pancreatic + + + + + + + + + + + + + + + + + + + + + + + + + 

Adenoma 

Parathyroid gland + + + + + + + + + + M + + + + + + + + + + + + + + 

Pituitary gland + + + + + + + + + + + + + + + + + + + + + + + + + 

Pars distalis, adenoma X X X X X X X X X X X X X X 

Pars distalis, adenoma, multiple 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + 

C-cell, adenoma X X X 

C-cell, carcinoma X 

Follicular cell, adenoma 

Follicular cell, carcinoma X 

General Body System 

None 

Genital System 

Clitoral gland + + + + + + + + + + + + + + + + + + + + + M + + + 

Adenoma X X 

Carcinoma 

Bilateral, adenoma X 

Ovary + + + + + + + + + + + + + + + + + + + + + + + + + 

Granulosa cell tumor benign 

Uterus + + + + + + + + + + + + + + + + + + + + + + + + + 

Polyp stromal 

Sarcoma stromal 

+: Tissue examined microscopically M: Missing tissue X: Lesion present 

A: Autolysis precludes examination I: Insufficient tissue Blank: Not examined 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 115 

TABLE B2
 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 0 ppm (continued)
 

7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 

3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Total 

Carcass ID Number 2 3 3 3 3 3 3 4 4 4 1 1 1 1 1 2 2 3 3 4 4 4 4 4 4 Tissues/ 

1 0 3 5 6 8 9 3 4 8 0 6 7 8 9 5 7 2 4 0 2 5 6 7 9 Tumors 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, colon + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Polyp adenomatous 1 

Intestine large, rectum + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, cecum + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine small, duodenum + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine small, jejunum + + + + + + + + + + + + + + + + + + + + + + + + + 46 

Intestine small, ileum + + + + + + + + + + + + + + + + + + + + + + + + + 47 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Mesentery + + + + + 10 

Pancreas + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Salivary glands + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Cardiovascular System 

Blood vessel + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Pheochromocytoma malignant 1 

Pheochromocytoma complex 1 

Pheochromocytoma benign X 1 

Islets, pancreatic + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Adenoma X 1 

Parathyroid gland + + M + + M + + + + + M + + + M + + + M + + M M + 42 

Pituitary gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Pars distalis, adenoma X X X X X X X X X X X X X X X X 30 

Pars distalis, adenoma, multiple X 1 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

C-cell, adenoma X X X 6 

C-cell, carcinoma 1 

Follicular cell, adenoma X 1 

Follicular cell, carcinoma 1 

General Body System 

None 

Genital System 

Clitoral gland + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Adenoma X X X X 6 

Carcinoma X 1 

Bilateral, adenoma 1 

Ovary + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Granulosa cell tumor benign X 1 

Uterus + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Polyp stromal X X 2 

Sarcoma stromal X 1 
 

 

 

 

 

 

 

 

 

 

116 Oxazepam, NTP TR 468 

TABLE B2
 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 0 ppm (continued)
 

Number of Days on Study 

2 

2 

3 

2 

2 

8 

5 

2 

2 

5 

2 

9 

5 

5 

0 

5 

6 

9 

5 

7 

1 

5 

8 

3 

5 

9 

7 

6 

1 

3 

6 

4 

1 

6 

4 

7 

6 

9 

0 

6 

9 

6 

6 

9 

7 

7 

0 

0 

7 

0 

1 

7 

0 

8 

7 

2 

9 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

Carcass ID Number 

3 

0 

1 

3 

2 

2 

3 

0 

5 

3 

0 

4 

3 

4 

1 

3 

2 

3 

3 

2 

9 

3 

5 

0 

3 

0 

9 

3 

3 

7 

3 

0 

8 

3 

2 

4 

3 

3 

1 

3 

1 

5 

3 

0 

2 

3 

2 

6 

3 

2 

8 

3 

1 

4 

3 

0 

6 

3 

0 

3 

3 

0 

7 

3 

1 

1 

3 

1 

2 

3 

1 

3 

3 

2 

0 

Hematopoietic System 

Bone marrow 

Lymph node 

Deep cervical, carcinoma, metastatic,

 thyroid gland 

Renal, pheochromocytoma malignant,

 metastatic, adrenal medulla 

Lymph node, mandibular 

Lymph node, mesenteric 

Spleen 

Thymus 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + 

X 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Integumentary System 

Mammary gland 

Adenoma 

Carcinoma 

Fibroadenoma 

Fibroadenoma, multiple 

Skin 

M + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X 

X X X X 

X X X X X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Musculoskeletal System 

Bone 

Osteosarcoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

Nervous System 

Brain 

Oligodendroglioma malignant 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

Respiratory System 

Lung 

Nose 

Trachea 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Eye + 

Urinary System 

Kidney 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + A + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X X X X 
 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 117 

TABLE B2
 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 0 ppm (continued)
 

7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 

3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Total 

Carcass ID Number 2 3 3 3 3 3 3 4 4 4 1 1 1 1 1 2 2 3 3 4 4 4 4 4 4 Tissues/ 

1 0 3 5 6 8 9 3 4 8 0 6 7 8 9 5 7 2 4 0 2 5 6 7 9 Tumors 

Hematopoietic System 

Bone marrow + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Lymph node 4 

Deep cervical, carcinoma, metastatic,

 thyroid gland 1 

Renal, pheochromocytoma malignant,

 metastatic, adrenal medulla 1 

Lymph node, mandibular + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Lymph node, mesenteric + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Spleen + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Thymus + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Integumentary System 

Mammary gland + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Adenoma 1 

Carcinoma X 2 

Fibroadenoma X X X X X X X 11 

Fibroadenoma, multiple X X X X X X X X X 14 

Skin + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Osteosarcoma 1 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Oligodendroglioma malignant 1 

Respiratory System 

Lung + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Nose + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Trachea + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Special Senses System 

Eye +

Urinary System 

Kidney + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Urinary bladder + + + + + + + + + + + + + + + + + + + M + + + + + 48 

Systemic Lesions 

Multiple organs + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Leukemia mononuclear X X X X X X 14 

 2 
 

 

 

 

 

 

 

 

 

 

 

118 Oxazepam, NTP TR 468 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 625 ppm 

Number of Days on Study 

2 4 4 4 5 5 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 

8 0 7 7 5 9 0 1 3 3 3 4 5 6 6 9 0 1 1 1 1 1 1 2 2 

8 0 5 8 0 0 6 2 1 3 4 7 4 6 9 7 8 5 7 8 8 8 8 8 9 

Carcass ID Number 

3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

9 8 8 5 8 5 6 5 7 6 8 6 8 7 5 6 8 6 5 5 6 7 9 5 7 

0 0 4 8 1 7 6 6 5 4 3 7 2 4 2 3 7 9 5 4 5 0 3 1 3 

Alimentary System 

Esophagus 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Mesentery 

Pancreas 

Salivary glands 

Stomach, forestomach 

Stomach, glandular 

Tongue 

Squamous cell carcinoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

A + + + + + A + + + + + + + + + + + + + + + + + + 

A + + + + + + + + + + + + + + + + + + + + + + + + 

A + + + + + A + + + + + + + + + + + + + + + + + + 

A + + + + + + + + + + + + + + + + + + + + + + + + 

A + + + + + A + + + + + + + + + + + + + + + + + + 

A + A + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ 

X 

Cardiovascular System 

Blood vessel + + + + + + + + + + + + + + + + + + + + + + + + + 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 

Adenoma 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + 

Pheochromocytoma benign X X 

Islets, pancreatic + + + + + + + + + + + + + + + + + + + + + + + + + 

Parathyroid gland + + + + M + M + + + + M + + M + + + + + M + + + M 

Pituitary gland + + + + + + + + + + + + + + + + + + + + + + + + + 

Pars distalis, adenoma X X X X X X X X X X 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + 

C-cell, adenoma X 

General Body System 

None 

Genital System 

Clitoral gland + + + + + + + + + + + + + + + + + + + + + + + + + 

Adenoma X 

Ovary + + + + + + + + + + + + + + + + + + + + + + + + + 

Uterus + + + + + + + + + + + + + + + + + + + + + + + + + 

Polyp stromal X X 

Vagina + 

Hematopoietic System 

Bone marrow + + + + + + + + + + + + + + + + + + + + + + + + + 

Lymph node + + 

Lymph node, mandibular M + + + + + + + + + + + + + + + + + + + + M + + + 

Lymph node, mesenteric + + + + + + + + + + + + + + + + + + + + + + + + + 

Spleen + + + + + + + + + + + + + + + + + + + + + + + + + 

Thymus + + + + + + + + + + + + + + + + + + + + M + + + M 
 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 119 

TABLE B2
 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 625 ppm (continued)
 

7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

9 9 9 9 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 

3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 3 3 3 3 3 3 3 3 3 3 Total 

Carcass ID Number 7 8 9 9 5 5 6 7 7 7 7 7 8 9 0 6 6 6 8 8 9 9 9 9 9 Tissues/ 

6 6 4 7 3 9 1 1 2 7 8 9 5 6 0 0 2 8 8 9 1 2 5 8 9 Tumors 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, colon + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Intestine large, rectum + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Intestine large, cecum + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Intestine small, duodenum + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Intestine small, jejunum + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Intestine small, ileum + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Mesentery + + + + 9 

Pancreas + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Salivary glands + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Tongue 1 

Squamous cell carcinoma 1 

Cardiovascular System 

Blood vessel + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Adenoma X 1 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Pheochromocytoma benign X 3 

Islets, pancreatic + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Parathyroid gland M M + + + + M M + M + + M + + + + + + + + + + + + 38 

Pituitary gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Pars distalis, adenoma X X X X X X X X X X X X X X X X X X 28 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

C-cell, adenoma X X 3 

General Body System 

None 

Genital System 

Clitoral gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Adenoma X X 3 

Ovary + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Uterus + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Polyp stromal X X 4 

Vagina 1 

Hematopoietic System 

Bone marrow + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Lymph node 2 

Lymph node, mandibular + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Lymph node, mesenteric + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Spleen + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Thymus + + + + + + + + + + + + + + + + + + + + + + + + + 48 
 

 

 

 

 

 

 

 

 

 

 

120 Oxazepam, NTP TR 468 

TABLE B2
 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 625 ppm (continued)
 

Number of Days on Study 

2 

8 

8 

4 

0 

0 

4 

7 

5 

4 

7 

8 

5 

5 

0 

5 

9 

0 

6 

0 

6 

6 

1 

2 

6 

3 

1 

6 

3 

3 

6 

3 

4 

6 

4 

7 

6 

5 

4 

6 

6 

6 

6 

6 

9 

6 

9 

7 

7 

0 

8 

7 

1 

5 

7 

1 

7 

7 

1 

8 

7 

1 

8 

7 

1 

8 

7 

1 

8 

7 

2 

8 

7 

2 

9 

Carcass ID Number 

3 

9 

0 

3 

8 

0 

3 

8 

4 

3 

5 

8 

3 

8 

1 

3 

5 

7 

3 

6 

6 

3 

5 

6 

3 

7 

5 

3 

6 

4 

3 

8 

3 

3 

6 

7 

3 

8 

2 

3 

7 

4 

3 

5 

2 

3 

6 

3 

3 

8 

7 

3 

6 

9 

3 

5 

5 

3 

5 

4 

3 

6 

5 

3 

7 

0 

3 

9 

3 

3 

5 

1 

3 

7 

3 

Integumentary System 

Mammary gland M + + + + + + + + + + + + + + + + + + + + + + + + 

Adenoma X 

Carcinoma X 

Fibroadenoma X X X X X X X X 

Fibroadenoma, multiple X X 

Skin + + + + + + + + + + + + + + + + + + + + + + + + + 

Basal cell carcinoma 

Fibrosarcoma X 

Sebaceous gland, adenoma X 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain 

Astrocytoma benign 

Peripheral nerve 

Spinal cord 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ 

+ 

Respiratory System 

Lung 

Alveolar/bronchiolar carcinoma 

Nose 

Trachea 

Special Senses System 

Eye 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

Urinary System 

Kidney 

Nephroblastoma 

Urinary bladder 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + + + M + + + + + + + + + + + + + + + + + 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X X X X X X X X X 
 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 121 

TABLE B2
 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 625 ppm (continued)
 

7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

9 9 9 9 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 

3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 3 3 3 3 3 3 3 3 3 3 Total 

Carcass ID Number 7 8 9 9 5 5 6 7 7 7 7 7 8 9 0 6 6 6 8 8 9 9 9 9 9 Tissues/ 

6 6 4 7 3 9 1 1 2 7 8 9 5 6 0 0 2 8 8 9 1 2 5 8 9 Tumors 

Integumentary System 

Mammary gland + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Adenoma X 2 

Carcinoma X X 3 

Fibroadenoma X X X X X X 14 

Fibroadenoma, multiple X X X 5 

Skin + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Basal cell carcinoma X 1 

Fibrosarcoma X 2 

Sebaceous gland, adenoma 1 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Astrocytoma benign X 1 

Peripheral nerve 1 

Spinal cord 1 

Respiratory System 

Lung + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Alveolar/bronchiolar carcinoma 1 

Nose + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Trachea + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Special Senses System 

Eye +

Urinary System 

Kidney + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Nephroblastoma 1 

Urinary bladder + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Systemic Lesions 

Multiple organs + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Leukemia mononuclear X X X X X X 19 

50 

 1 
 

 

 

 

 

 

 

 

 

 

 

122 Oxazepam, NTP TR 468 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 2,500 ppm 

Number of Days on Study 

4 

1 

4 

4 

3 

2 

4 

5 

3 

5 

0 

6 

5 

3 

9 

5 

4 

0 

5 

5 

0 

5 

5 

6 

5 

6 

5 

5 

7 

8 

5 

8 

3 

5 

8 

5 

5 

8 

9 

5 

9 

7 

5 

9 

7 

6 

1 

1 

6 

3 

2 

6 

3 

3 

6 

3 

4 

6 

4 

6 

6 

5 

2 

6 

6 

9 

6 

9 

2 

6 

9 

7 

7 

0 

0 

Carcass ID Number 

4 

7 

7 

4 

8 

9 

4 

8 

4 

4 

8 

8 

4 

6 

1 

4 

6 

8 

4 

7 

1 

4 

7 

9 

4 

7 

0 

4 

7 

5 

4 

5 

9 

4 

6 

4 

4 

7 

2 

4 

5 

2 

4 

9 

4 

4 

6 

5 

4 

9 

3 

4 

9 

9 

4 

9 

7 

4 

8 

1 

4 

6 

0 

4 

9 

2 

4 

6 

3 

4 

8 

6 

4 

5 

5 

Alimentary System 

Esophagus 

Intestine large, colon 

Intestine large, rectum 

Intestine large, cecum 

Intestine small, duodenum 

Intestine small, jejunum 

Intestine small, ileum 

Liver 

Mesentery 

Pancreas 

Salivary glands 

Stomach, forestomach 

Stomach, glandular 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

A 

A 

A 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

A 

A 

A 

A 

A 

A 

+ 

A 

M 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

A 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

A 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

A 

A 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

M 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

Cardiovascular System 

Blood vessel + 

Heart + 

Endocrine System 

Adrenal cortex + 

Adenoma 

Adrenal medulla + 

Islets, pancreatic + 

Parathyroid gland + 

Adenoma 

Pituitary gland + 

Pars distalis, adenoma 

Pars distalis, adenoma, multiple 

Pars distalis, carcinoma 

Thyroid gland + 

C-cell, adenoma 

C-cell, carcinoma 

Follicular cell, carcinoma 

General Body System 

None 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

M 

+ 

+ 

A 

M 

+ 

M 

+ 

+ 

+ 

+ 

+ 

M 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

M 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

X 

+ 

+ 

+ 

+ 

+ 

M 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

M 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

M 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

M 

+ 

M 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

Genital System 

Clitoral gland + 

Adenoma 

Carcinoma 

Ovary + 

Uterus + 

Polyp stromal 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

Hematopoietic System 

Bone marrow + 

Lymph node + 

Lymph node, mandibular + 

Lymph node, mesenteric + 

Spleen + 

Thymus + 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

M 

+ 

+ 

M 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

M 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 
 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 123 

TABLE B2
 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 2,500 ppm (continued)
 

7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 0 0 0 0 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

0 1 3 3 8 9 9 9 9 9 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 

4 4 4 4 4 4 4 4 4 5 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 Total 

Carcass ID Number 8 7 7 9 8 5 6 8 9 0 5 5 6 6 6 7 7 8 9 5 5 5 8 9 9 Tissues/ 

2 3 6 8 5 8 9 3 5 0 1 7 2 6 7 4 8 7 1 3 4 6 0 0 6 Tumors 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, colon + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Intestine large, rectum + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Intestine large, cecum + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Intestine small, duodenum + + + + + + + + + + + + + + + + + + + + + + + + + 47 

Intestine small, jejunum + + + + + + + + + + + + + + + + + + + + + + + + + 47 

Intestine small, ileum + + + + + + + + + + + + + + + + + + + + + + + + + 46 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Mesentery + + 4 

Pancreas + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Salivary glands + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Cardiovascular System 

Blood vessel + 

Heart + 

Endocrine System 

Adrenal cortex + 

Adenoma X

Adrenal medulla + 

Islets, pancreatic + 

Parathyroid gland + 

Adenoma 

Pituitary gland + 

Pars distalis, adenoma X 

Pars distalis, adenoma, multiple 

Pars distalis, carcinoma 

Thyroid gland + 

C-cell, adenoma 

C-cell, carcinoma 

Follicular cell, carcinoma 

General Body System 

None 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

M 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

M 

+ 

X 

+ 

X

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

M 

+ 

X

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X

+ 

X 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

X

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

X

+ 

+ 

+ 

+ 

+ 

M 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 50 

+ 49 

+ 50 

1 

+ 50 

+ 49 

M 38 

1 

+ 50 

20 

X 1 

1 

+ 48 

6 

1 

3 

Genital System 

Clitoral gland + 

Adenoma 

Carcinoma

Ovary + 

Uterus + 

Polyp stromal 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 50 

3 

1 

+ 50 

+ 50 

3 

Hematopoietic System 

Bone marrow + 

Lymph node 

Lymph node, mandibular + 

Lymph node, mesenteric + 

Spleen + 

Thymus + 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

M 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+

+ 

+ 

+ 

M 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 50 

9 

+ 48 

+ 50 

+ 50 

M 46 
 

 

 

 

 

 

124 Oxazepam, NTP TR 468 

TABLE B2
 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 2,500 ppm (continued)
 

Number of Days on Study 

4 

1 

4 

4 

3 

2 

4 

5 

3 

5 

0 

6 

5 

3 

9 

5 

4 

0 

5 

5 

0 

5 

5 

6 

5 

6 

5 

5 

7 

8 

5 

8 

3 

5 

8 

5 

5 

8 

9 

5 

9 

7 

5 

9 

7 

6 

1 

1 

6 

3 

2 

6 

3 

3 

6 

3 

4 

6 

4 

6 

6 

5 

2 

6 

6 

9 

6 

9 

2 

6 

9 

7 

7 

0 

0 

Carcass ID Number 

4 

7 

7 

4 

8 

9 

4 

8 

4 

4 

8 

8 

4 

6 

1 

4 

6 

8 

4 

7 

1 

4 

7 

9 

4 

7 

0 

4 

7 

5 

4 

5 

9 

4 

6 

4 

4 

7 

2 

4 

5 

2 

4 

9 

4 

4 

6 

5 

4 

9 

3 

4 

9 

9 

4 

9 

7 

4 

8 

1 

4 

6 

0 

4 

9 

2 

4 

6 

3 

4 

8 

6 

4 

5 

5 

Integumentary System 

Mammary gland 

Fibroadenoma 

Fibroadenoma, multiple 

Skin 

Trichoepithelioma 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain + 

Carcinoma, metastatic, pituitary gland 

Respiratory System 

Lung + 

Carcinoma, metastatic, thyroid gland 

Nose + 

Trachea + 

Special Senses System 

None 

Urinary System 

Kidney + 

Urinary bladder + 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

M 

+ 

M 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

A 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

Systemic Lesions 

Multiple organs + + + + + + + + + + + + + + + + + + + + + + + + + 

Leukemia mononuclear X X X X X X X X X X X X X X X X X X 
 

 

 

 

 

 

Oxazepam, NTP TR 468 125 

TABLE B2
 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 2,500 ppm (continued)
 

7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 0 0 0 0 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

0 1 3 3 8 9 9 9 9 9 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 

4 4 4 4 4 4 4 4 4 5 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 Total 

Carcass ID Number 8 7 7 9 8 5 6 8 9 0 5 5 6 6 6 7 7 8 9 5 5 5 8 9 9 Tissues/ 

2 3 6 8 5 8 9 3 5 0 1 7 2 6 7 4 8 7 1 3 4 6 0 0 6 Tumors 

Integumentary System 

Mammary gland + + + + + + M + + + + + + + + + + + + + + + + + + 49 

Fibroadenoma X X X X X 8 

Fibroadenoma, multiple X 1 

Skin + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Trichoepithelioma X 1 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Nervous System 

Brain + 

Carcinoma, metastatic, pituitary gland 

Respiratory System 

Lung + 

Carcinoma, metastatic, thyroid gland 

Nose + 

Trachea + 

Special Senses System 

None 

Urinary System 

Kidney + 

Urinary bladder + 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 50 

1 

+ 49 

1 

+ 50 

+ 49 

+ 50 

+ 49 

Systemic Lesions 

Multiple organs + 

Leukemia mononuclear X 

+ + 

X 

+ 

X 

+ 

X 

+ 

X 

+ 

X 

+ + 

X 

+ + + + + 

X 

+ + + 

X 

+ + + + + + 

X 

+ 

X 

+ 50 

29 
 

 

 

 

 

 

 

 

 

 

 

 

126 Oxazepam, NTP TR 468 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 5,000 ppm 

0 4 5 6 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 1 1 5 1 2 3 3 3 4 4 6 7 7 8 0 1 1 1 2 2 2 2 2 2 2 

7 3 0 3 4 1 4 8 1 6 9 5 9 3 0 1 5 5 1 9 9 9 9 9 9 

5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 

Carcass ID Number 4 2 3 0 1 2 1 4 4 0 2 1 4 3 3 4 0 4 4 0 0 1 1 1 4 

9 3 8 9 5 5 8 2 1 2 2 1 8 2 1 5 3 6 4 4 5 0 2 7 0 

Alimentary System 

Esophagus M + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine large, colon + + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine large, rectum + + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine large, cecum A + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine small, duodenum A + + + + + + + + + + + + + + + + + + + + + + + + 

Intestine small, jejunum A + A + + + + + + + + + + + + + + + + + + + + + + 

Intestine small, ileum A + + + + + + + + + + + + + + + + + + + + + + + + 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + 

Mesentery + + + 

Pancreas M + + + + + + + + + + + + + + + + + + + + + + + + 

Acinus, adenoma X 

Salivary glands M + + + + + + + + + + + + + + + + + + + + + + + + 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + 

Cardiovascular System 

Blood vessel M + + + + + + + + + + + + + + + + + + + + + + + + 

Heart M + + + + + + + + + + + + + + + + + + + + + + + + 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + 

Pheochromocytoma benign 

Islets, pancreatic M + + + + + + + + + + + + + + + + + + + + + + + + 

Parathyroid gland M + M M M M + + + + + + M + + + M + + + M + M + + 

Pituitary gland + + + + + + + + + + + + + + + + + + + + + + + + + 

Pars distalis, adenoma X X X X X X X X 

Thyroid gland M + + + + + + + + + + + + + + + + + + + + + + + + 

C-cell, adenoma X 

C-cell, carcinoma X 

Follicular cell, adenoma 

Follicular cell, carcinoma 

General Body System 

Peritoneum + 

Genital System 

Clitoral gland + + + + + + + + + + + + + + + + + + + + + + + + + 

Adenoma X X X 

Ovary + + + + + + + + + + + + + + + + + + + + + + + + + 

Tubulostromal adenoma 

Uterus + + + + + + + + + + + + + + + + + + + + + + + + + 

Polyp stromal X X 

Sarcoma stromal X 

Hematopoietic System 

Bone marrow + + + + + + + + + + + + + + + + + + + + + + + + + 

Lymph node + + + 

Lymph node, mandibular M + + + + + + + + + + + + + + + + + + + + + + + + 

Lymph node, mesenteric A + + + + + + + + + + + + + + + + + + + + + + + + 

Spleen M + + + + + + + + + + + + + + + + + + + + + + + + 

Thymus M + + + + + + + M + + + + + + + + + + + + + + + + 
 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 127 

TABLE B2
 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 5,000 ppm (continued)
 

7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 

Number of Days on Study 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

9 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 

5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 Total 

Carcass ID Number 4 1 2 2 2 3 3 3 3 3 4 0 0 0 0 1 1 1 2 2 2 2 3 3 5 Tissues/ 

7 9 6 7 8 3 4 5 7 9 3 1 6 7 8 3 4 6 0 1 4 9 0 6 0 Tumors 

Alimentary System 

Esophagus + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Intestine large, colon + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, rectum + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Intestine large, cecum + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Intestine small, duodenum + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Intestine small, jejunum + + + + + + + + + + + + + + + + + + + + + + + + + 48 

Intestine small, ileum + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Liver + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Mesentery + + + 6 

Pancreas + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Acinus, adenoma 1 

Salivary glands + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Stomach, forestomach + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Stomach, glandular + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Cardiovascular System 

Blood vessel + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Heart + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Endocrine System 

Adrenal cortex + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Adrenal medulla + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Pheochromocytoma benign X 1 

Islets, pancreatic + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Parathyroid gland + + + + + + M + + + M M + M + M M M + M + + + + + 33 

Pituitary gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Pars distalis, adenoma X X X X 12 

Thyroid gland + + + + + + + + + + + + + + + + + + + + + + + + + 49 

C-cell, adenoma X 2 

C-cell, carcinoma 1 

Follicular cell, adenoma X X 2 

Follicular cell, carcinoma X 1 

General Body System 

Peritoneum 1 

Genital System 

Clitoral gland + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Adenoma X 4 

Ovary + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Tubulostromal adenoma X 1 

Uterus + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Polyp stromal X X 4 

Sarcoma stromal 1 

Hematopoietic System 

Bone marrow + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Lymph node 3 

Lymph node, mandibular + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Lymph node, mesenteric + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Spleen + + + + + + + + + + + + + + + + + + + + + + + + + 49 

Thymus + + + + + + + + + + M + + + + + + + + + + + + + + 47 
 

 

 

 

 

 

 

128 Oxazepam, NTP TR 468 

TABLE B2
 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 5,000 ppm (continued)
 

Number of Days on Study 

0 

1 

7 

4 

1 

3 

5 

5 

0 

6 

1 

3 

6 

2 

4 

6 

3 

1 

6 

3 

4 

6 

3 

8 

6 

4 

1 

6 

4 

6 

6 

6 

9 

6 

7 

5 

6 

7 

9 

6 

8 

3 

7 

0 

0 

7 

1 

1 

7 

1 

5 

7 

1 

5 

7 

2 

1 

7 

2 

9 

7 

2 

9 

7 

2 

9 

7 

2 

9 

7 

2 

9 

7 

2 

9 

Carcass ID Number 

5 

4 

9 

5 

2 

3 

5 

3 

8 

5 

0 

9 

5 

1 

5 

5 

2 

5 

5 

1 

8 

5 

4 

2 

5 

4 

1 

5 

0 

2 

5 

2 

2 

5 

1 

1 

5 

4 

8 

5 

3 

2 

5 

3 

1 

5 

4 

5 

5 

0 

3 

5 

4 

6 

5 

4 

4 

5 

0 

4 

5 

0 

5 

5 

1 

0 

5 

1 

2 

5 

1 

7 

5 

4 

0 

Integumentary System 

Mammary gland 

Fibroadenoma 

Fibroadenoma, multiple 

Skin 

Fibroma 

Keratoacanthoma 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 

Respiratory System 

Lung 

Alveolar/bronchiolar adenoma 

Nose 

Trachea 

M + + + + + + + + + + + + + + + + + + + + + + + + 

X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

M + + + + + + + + + + + + + + + + + + + + + + + + 

Special Senses System 

Eye 

Zymbal’s gland 

Carcinoma 

+ 

X 

+ 

Urinary System 

Kidney 

Urinary bladder 

Sarcoma stromal, metastatic, uterus 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X X X X X X X X 
 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 129 

TABLE B2
 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 5,000 ppm (continued)
 

Number of Days on Study 

7 

2 

9 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

Carcass ID Number 

5 

4 

7 

5 

1 

9 

5 

2 

6 

5 

2 

7 

5 

2 

8 

5 

3 

3 

5 

3 

4 

5 

3 

5 

5 

3 

7 

5 

3 

9 

5 

4 

3 

5 

0 

1 

5 

0 

6 

5 

0 

7 

5 

0 

8 

5 

1 

3 

5 

1 

4 

5 

1 

6 

5 

2 

0 

5 

2 

1 

5 

2 

4 

5 

2 

9 

5 

3 

0 

5 

3 

6 

5 

5 

0 

Total 

Tissues/ 

Tumors 

Integumentary System 

Mammary gland 

Fibroadenoma 

Fibroadenoma, multiple 

Skin 

Fibroma 

Keratoacanthoma

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X X 

X

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X

50 

12 

1 

50 

1 

1 

Musculoskeletal System 

Bone + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Nervous System 

Brain + + + + + + + + + + + + + + + + + + + + + + + + + 50 

Respiratory System 

Lung 

Alveolar/bronchiolar adenoma 

Nose 

Trachea 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

49 

2 

50 

49 

Special Senses System 

Eye

Zymbal’s gland 

Carcinoma 

+

X

 1 

2 

2 

Urinary System 

Kidney 

Urinary bladder 

Sarcoma stromal, metastatic, uterus

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

50 

50 

1 

Systemic Lesions 

Multiple organs 

Leukemia mononuclear 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X X 

50 

18 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

130 Oxazepam, NTP TR 468 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 10,000 ppm 

(Stop-Exposure) 

Number of Days on Study 

4 

7 

8 

5 

0 

6 

5 

6 

2 

5 

6 

2 

5 

6 

2 

5 

7 

0 

5 

8 

5 

5 

9 

9 

6 

0 

4 

6 

0 

9 

6 

0 

9 

6 

4 

6 

6 

6 

2 

6 

6 

9 

6 

6 

9 

6 

9 

7 

6 

9 

9 

7 

0 

3 

7 

1 

4 

7 

1 

5 

7 

1 

6 

7 

1 

8 

7 

1 

9 

7 

2 

5 

7 

2 

5 

Carcass ID Number 

5 

6 

4 

5 

9 

6 

5 

6 

3 

5 

7 

0 

5 

9 

9 

5 

8 

1 

5 

7 

2 

5 

6 

8 

5 

7 

1 

5 

6 

2 

5 

6 

6 

5 

9 

0 

5 

6 

9 

5 

5 

4 

5 

8 

5 

5 

8 

0 

5 

7 

3 

5 

7 

4 

5 

7 

5 

5 

9 

4 

5 

8 

7 

5 

9 

8 

5 

7 

6 

5 

5 

6 

5 

5 

8 

Alimentary System 

Esophagus 

Intestine small, duodenum 

Intestine small, jejunum 

Liver 

Histiocytic sarcoma, metastatic, skin 

Mesentery 

Salivary glands 

Myoepithelioma 

Stomach, forestomach 

Stomach, glandular 

+ 

+ 

+ 

+ 

A 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

A 

+ 

+ 

A 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

X 

+ 

+ 

Cardiovascular System 

None 

Endocrine System 

Adrenal cortex 

Adenoma 

Pituitary gland 

Pars distalis, adenoma 

Thyroid gland + 

Bilateral, C-cell, adenoma 

C-cell, adenoma 

General Body System 

None 

+ 

+ 

+ 

X 

+ 

X 

+ 

+ 

X 

+ + + 

+ 

X 

+ + 

+ 

X 

+ 

+ 

X 

+ 

+ 

X 

+ 

+ 

X 

+ + 

+ 

X 

+ 

+ 

X 

+ 

X 

+ 

+ 

X 

+ 

+ 

+ 

X 

+ 

+ 

+ 

+ 

X 

+ 

+ 

X 

+ 

+ 

X 

+ 

+ 

+ 

+ 

X 

+ 

+ 

+ 

Genital System 

Clitoral gland + + + 

Adenoma X X 

Ovary + + 

Uterus + + + 

Sarcoma stromal 

Vagina + 

Hematopoietic System 

Lymph node + + + 

Lymph node, mandibular + + 

Squamous cell carcinoma, metastatic, skin X 

Lymph node, mesenteric + + 

Spleen + + + + + + + + 

Integumentary System 

Mammary gland + + + + + + + + + 

Carcinoma, multiple X 

Fibroadenoma X X X X X X X 

Fibroadenoma, multiple X X 

Skin + + + + + + 

Fibroma X X 

Squamous cell carcinoma X 

Subcutaneous tissue, histiocytic sarcoma X 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 131 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 10,000 ppm 

(Stop-Exposure) (continued) 

Number of Days on Study 

7 

2 

9 

7 

2 

9 

7 

2 

9 

7 

2 

9 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

Carcass ID Number 

5 

5 

1 

5 

7 

7 

5 

9 

1 

5 

9 

5 

5 

5 

3 

5 

6 

0 

5 

6 

5 

5 

7 

9 

5 

8 

3 

5 

8 

6 

5 

8 

9 

5 

9 

2 

6 

0 

0 

5 

5 

2 

5 

5 

5 

5 

5 

7 

5 

5 

9 

5 

6 

1 

5 

6 

7 

5 

7 

8 

5 

8 

2 

5 

8 

4 

5 

8 

8 

5 

9 

3 

5 

9 

7 

Total 

Tissues/ 

Tumors 

Alimentary System 

Esophagus 

Intestine small, duodenum 

Intestine small, jejunum 

Liver 

Histiocytic sarcoma, metastatic, skin

Mesentery 

Salivary glands

Myoepithelioma

Stomach, forestomach 

Stomach, glandular 

Cardiovascular System 

None 

+

+ + + + + + + + + + + + + + + + + + + + + + + A + 

+

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

1 

47 

1 

49 

1 

13 

1 

1 

50 

49 

Endocrine System 

Adrenal cortex

Adenoma

Pituitary gland 

Pars distalis, adenoma 

Thyroid gland 

Bilateral, C-cell, adenoma 

C-cell, adenoma 

General Body System 

None 

+ + + + + + + + + + + + + + + + 

X X X X X X X X 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X

X X

 2 

1 

35 

23 

50 

2 

2 

Genital System 

Clitoral gland 

Adenoma 

Ovary 

Uterus 

Sarcoma stromal 

Vagina

+ 

X 

+ 

+ + + 

X X 

+ 

X

+ 

+

+ 

X 

+ + 

X

+

11 

7 

4 

5 

1 

1 

Hematopoietic System 

Lymph node 

Lymph node, mandibular 

Squamous cell carcinoma, metastatic, skin

Lymph node, mesenteric

Spleen + + 

+

+

+ + 

4 

3 

1 

2 

12 

Integumentary System 

Mammary gland 

Carcinoma, multiple

Fibroadenoma 

Fibroadenoma, multiple 

Skin

Fibroma

Squamous cell carcinoma

Subcutaneous tissue, histiocytic sarcoma

+ + + + 

X X X 

X 

+ + 

X X 

+ + 

X 

X 

+ + + + + 

X X X 

X X

+ 

X 

23 

1 

17 

6 

6 

2 

1 

1 
 

 

 

 

 

132 Oxazepam, NTP TR 468 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 10,000 ppm 

(Stop-Exposure) (continued) 

Number of Days on Study 

4 

7 

8 

5 

0 

6 

5 

6 

2 

5 

6 

2 

5 

6 

2 

5 

7 

0 

5 

8 

5 

5 

9 

9 

6 

0 

4 

6 

0 

9 

6 

0 

9 

6 

4 

6 

6 

6 

2 

6 

6 

9 

6 

6 

9 

6 

9 

7 

6 

9 

9 

7 

0 

3 

7 

1 

4 

7 

1 

5 

7 

1 

6 

7 

1 

8 

7 

1 

9 

7 

2 

5 

7 

2 

5 

Carcass ID Number 

5 

6 

4 

5 

9 

6 

5 

6 

3 

5 

7 

0 

5 

9 

9 

5 

8 

1 

5 

7 

2 

5 

6 

8 

5 

7 

1 

5 

6 

2 

5 

6 

6 

5 

9 

0 

5 

6 

9 

5 

5 

4 

5 

8 

5 

5 

8 

0 

5 

7 

3 

5 

7 

4 

5 

7 

5 

5 

9 

4 

5 

8 

7 

5 

9 

8 

5 

7 

6 

5 

5 

6 

5 

5 

8 

Musculoskeletal System 

Bone + 

Nervous System 

None 

Respiratory System 

None 

Special Senses System 

Eye + 

Urinary System 

Kidney + 

Systemic Lesions 

Multiple organs 

Histiocytic sarcoma 

Leukemia mononuclear 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X 

X X X X X X X X X 
 

 

 

 

 

 

Oxazepam, NTP TR 468 133 

TABLE B2 

Individual Animal Tumor Pathology of Female Rats in the 2-Year Feed Study of Oxazepam: 10,000 ppm 

(Stop-Exposure) (continued) 

Number of Days on Study 

7 

2 

9 

7 

2 

9 

7 

2 

9 

7 

2 

9 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

0 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

7 

3 

1 

Carcass ID Number 

5 

5 

1 

5 

7 

7 

5 

9 

1 

5 

9 

5 

5 

5 

3 

5 

6 

0 

5 

6 

5 

5 

7 

9 

5 

8 

3 

5 

8 

6 

5 

8 

9 

5 

9 

2 

6 

0 

0 

5 

5 

2 

5 

5 

5 

5 

5 

7 

5 

5 

9 

5 

6 

1 

5 

6 

7 

5 

7 

8 

5 

8 

2 

5 

8 

4 

5 

8 

8 

5 

9 

3 

5 

9 

7 

Total 

Tissues/ 

Tumors 

Musculoskeletal System 

Bone 1 

Nervous System 

None 

Respiratory System 

None 

Special Senses System 

Eye + 2 

Urinary System 

Kidney 1 

Systemic Lesions 

Multiple organs 

Histiocytic sarcoma

Leukemia mononuclear 

+ + + + + + + + + + + + + + + + + + + + + + + + + 

X X X X X X 

50 

1 

15 
134 Oxazepam, NTP TR 468 

TABLE B3a 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Feed Study of Oxazepam 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 

Adrenal Medulla: Benign Pheochromocytoma a Overall rate 1/50 (2%) 3/50 (6%) 0/50 (0%) 1/50 (2%) 

Adjusted rateb 3.1% 9.4% 0.0% 3.2% c Terminal rate 1/32 (3%) 1/26 (4%) 0/20 (0%) 1/31 (3%) e First incidence (days) 729 (T) 550 — 729 (T) d Life table test P=0.326N P=0.258 P=0.594N P=0.755 

Logistic regression testd P=0.316N P=0.305 P=0.594N P=0.755 

Cochran-Armitage testd P=0.318N 

d Fisher exact test P=0.309 P=0.500N P=0.753N 

Adrenal Medulla: Benign, Complex, or Malignant Pheochromocytoma 

Overall rate 3/50 (6%) 3/50 (6%) 0/50 (0%) 1/50 (2%)
 

Adjusted rate 8.9% 9.4% 0.0% 3.2%
 

Terminal rate 2/32 (6%) 1/26 (4%) 0/20 (0%) 1/31 (3%)
 

First incidence (days) 700 550 — 729 (T)
 

Life table test P=0.127N P=0.596 P=0.204N P=0.312N 

Logistic regression test P=0.114N P=0.663N P=0.171N P=0.292N 

Cochran-Armitage test P=0.114N
 

Fisher exact test P=0.661N P=0.121N P=0.309N 

Clitoral Gland: Adenoma 

Overall rate 7/49 (14%) 3/50 (6%) 3/50 (6%) 4/50 (8%) 

Adjusted rate 19.4% 10.1% 9.6% 11.5% 

Terminal rate 4/31 (13%) 2/26 (8%) 1/20 (5%) 2/31 (6%) 

First incidence (days) 550 654 565 679 

Life table test P=0.306N P=0.210N P=0.309N P=0.259N 

Logistic regression test P=0.293N P=0.149N P=0.153N P=0.239N 

Cochran-Armitage test P=0.297N 

Fisher exact test P=0.151N P=0.151N P=0.251N 

Clitoral Gland: Adenoma or Carcinoma 

Overall rate 8/49 (16%) 3/50 (6%) 4/50 (8%) 4/50 (8%) 

Adjusted rate 22.4% 10.1% 12.5% 11.5% 

Terminal rate 5/31 (16%) 2/26 (8%) 1/20 (5%) 2/31 (6%) 

First incidence (days) 550 654 565 679 

Life table test P=0.253N P=0.145N P=0.360N P=0.179N 

Logistic regression test P=0.237N P=0.093N P=0.174N P=0.157N 

Cochran-Armitage test P=0.241N 

Fisher exact test P=0.094N P=0.168N P=0.168N 

Mammary Gland: Fibroadenoma 

Overall rate 25/50 (50%) 19/50 (38%) 9/50 (18%) 13/50 (26%) 

Adjusted rate 67.0% 52.8% 33.2% 35.1% 

Terminal rate 20/32 (63%) 10/26 (38%) 4/20 (20%) 8/31 (26%) 

First incidence (days) 529 612 589 550 

Life table test P=0.010N P=0.363N P=0.039N P=0.017N 

Logistic regression test P=0.003N P=0.152N P=0.003N P=0.007N 

Cochran-Armitage test P=0.005N 

Fisher exact test P=0.157N P<0.001N P=0.011N 
Oxazepam, NTP TR 468 135 

TABLE B3a
 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 

Mammary Gland: Fibroadenoma or Adenoma 

Overall rate 26/50 (52%) 20/50 (40%) 9/50 (18%) 13/50 (26%) 

Adjusted rate 67.8% 55.7% 33.2% 35.1% 

Terminal rate 20/32 (63%) 11/26 (42%) 4/20 (20%) 8/31 (26%) 

First incidence (days) 529 612 589 550 

Life table test P=0.006N P=0.372N P=0.028N P=0.011N 

Logistic regression test P=0.002N P=0.153N P=0.001N P=0.004N 

Cochran-Armitage test P=0.002N 

Fisher exact test P=0.158N P<0.001N P=0.007N 

Mammary Gland: Carcinoma 

Overall rate 2/50 (4%) 3/50 (6%) 0/50 (0%) 0/50 (0%)
 

Adjusted rate 5.1% 10.3% 0.0% 0.0%
 

Terminal rate 1/32 (3%) 2/26 (8%) 0/20 (0%) 0/31 (0%)
 

First incidence (days) 228 697 — —
 

Life table test P=0.060N P=0.443 P=0.288N P=0.243N 

Logistic regression test P=0.048N P=0.483 P=0.288N P=0.213N 

Cochran-Armitage test P=0.051N
 

Fisher exact test P=0.500 P=0.247N P=0.247N 

Mammary Gland: Adenoma or Carcinoma 

Overall rate 3/50 (6%) 5/50 (10%) 0/50 (0%) 0/50 (0%)
 

Adjusted rate 7.4% 16.8% 0.0% 0.0%
 

Terminal rate 1/32 (3%) 3/26 (12%) 0/20 (0%) 0/31 (0%)
 

First incidence (days) 228 697 — —
 

Life table test P=0.018N P=0.305 P=0.163N P=0.118N 

Logistic regression test P=0.013N P=0.347 P=0.130N P=0.109N 

Cochran-Armitage test P=0.014N
 

Fisher exact test P=0.357 P=0.121N P=0.121N 

Mammary Gland: Fibroadenoma, Adenoma, or Carcinoma 

Overall rate 27/50 (54%) 23/50 (46%) 9/50 (18%) 13/50 (26%) 

Adjusted rate 68.4% 62.7% 33.2% 35.1% 

Terminal rate 20/32 (63%) 13/26 (50%) 4/20 (20%) 8/31 (26%) 

First incidence (days) 228 612 589 550 

Life table test P=0.002N P=0.531N P=0.019N P=0.007N 

Logistic regression test P<0.001N P=0.268N P<0.001N P=0.003N 

Cochran-Armitage test P<0.001N 

Fisher exact test P=0.274N P<0.001N P=0.004N 

Pituitary Gland (Pars Distalis): Adenoma 

Overall rate 31/50 (62%) 28/50 (56%) 21/50 (42%) 12/50 (24%) 

Adjusted rate 73.6% 79.6% 62.0% 31.8% 

Terminal rate 21/32 (66%) 19/26 (73%) 9/20 (45%) 6/31 (19%) 

First incidence (days) 529 475 506 646 

Life table test P<0.001N P=0.479 P=0.504N P<0.001N 

Logistic regression test P<0.001N P=0.338N P=0.058N P<0.001N 

Cochran-Armitage test P<0.001N 

Fisher exact test P=0.342N P=0.036N P<0.001N 
136 Oxazepam, NTP TR 468 

TABLE B3a
 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 

Pituitary Gland (Pars Distalis): Adenoma or Carcinoma 

Overall rate 31/50 (62%) 28/50 (56%) 22/50 (44%) 12/50 (24%) 

Adjusted rate 73.6% 79.6% 65.4% 31.8% 

Terminal rate 21/32 (66%) 19/26 (73%) 10/20 (50%) 6/31 (19%) 

First incidence (days) 529 475 506 646 

Life table test P<0.001N P=0.479 P=0.548 P<0.001N 

Logistic regression test P<0.001N P=0.338N P=0.089N P<0.001N 

Cochran-Armitage test P<0.001N 

Fisher exact test P=0.342N P=0.054N P<0.001N 

Thyroid Gland (C-cell): Adenoma 

Overall rate 6/50 (12%) 3/50 (6%) 6/48 (13%) 2/49 (4%) 

Adjusted rate 16.5% 11.5% 23.4% 5.8% 

Terminal rate 3/32 (9%) 3/26 (12%) 3/20 (15%) 1/31 (3%) 

First incidence (days) 647 729 (T) 578 679 

Life table test P=0.217N P=0.324N P=0.364 P=0.147N 

Logistic regression test P=0.199N P=0.247N P=0.519 P=0.126N 

Cochran-Armitage test P=0.215N 

Fisher exact test P=0.243N P=0.591 P=0.141N 

Thyroid Gland (C-cell): Adenoma or Carcinoma 

Overall rate 7/50 (14%) 3/50 (6%) 7/48 (15%) 3/49 (6%) 

Adjusted rate 19.4% 11.5% 27.9% 8.5% 

Terminal rate 4/32 (13%) 3/26 (12%) 4/20 (20%) 1/31 (3%) 

First incidence (days) 647 729 (T) 578 679 

Life table test P=0.286N P=0.232N P=0.324 P=0.171N 

Logistic regression test P=0.266N P=0.162N P=0.480 P=0.096N 

Cochran-Armitage test P=0.289N 

Fisher exact test P=0.159N P=0.581 P=0.167N 

Thyroid Gland (Follicular Cell): Carcinoma 

Overall rate 1/50 (2%) 0/50 (0%) 3/48 (6%) 1/49 (2%)
 

Adjusted rate 2.5% 0.0% 12.4% 3.2%
 

Terminal rate 0/32 (0%) 0/26 (0%) 2/20 (10%) 1/31 (3%)
 

First incidence (days) 641 — 589 729 (T)
 

Life table test P=0.410 P=0.505N P=0.201 P=0.758N 

Logistic regression test P=0.395 P=0.504N P=0.285 P=0.759 

Cochran-Armitage test P=0.391 

Fisher exact test P=0.500N P=0.293 P=0.747 

Thyroid Gland (Follicular Cell): Adenoma or Carcinoma 

Overall rate 2/50 (4%) 0/50 (0%) 3/48 (6%) 3/49 (6%)
 

Adjusted rate 5.5% 0.0% 12.4% 9.7%
 

Terminal rate 1/32 (3%) 0/26 (0%) 2/20 (10%) 3/31 (10%)
 

First incidence (days) 641 — 589 729 (T)
 

Life table test P=0.192 P=0.265N P=0.344 P=0.493 

Logistic regression test P=0.185 P=0.237N P=0.461 P=0.517
 

Cochran-Armitage test P=0.170
 

Fisher exact test P=0.247N P=0.480 P=0.490
 
Oxazepam, NTP TR 468 137 

TABLE B3a
 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 

Uterus: Stromal Polyp 

Overall rate 2/50 (4%) 4/50 (8%) 3/50 (6%) 4/50 (8%) 

Adjusted rate 6.3% 13.6% 13.9% 10.9% 

Terminal rate 2/32 (6%) 2/26 (8%) 2/20 (10%) 2/31 (6%) 

First incidence (days) 729 (T) 718 703 631 

Life table test P=0.373 P=0.273 P=0.302 P=0.340 

Logistic regression test P=0.378 P=0.311 P=0.349 P=0.349 

Cochran-Armitage test P=0.365 

Fisher exact test P=0.339 P=0.500 P=0.339 

Uterus: Stromal Polyp or Stromal Sarcoma 

Overall rate 3/50 (6%) 4/50 (8%) 3/50 (6%) 5/50 (10%) 

Adjusted rate 9.4% 13.6% 13.9% 12.9% 

Terminal rate 3/32 (9%) 2/26 (8%) 2/20 (10%) 2/31 (6%) 

First incidence (days) 729 (T) 718 703 631 

Life table test P=0.338 P=0.415 P=0.443 P=0.364 

Logistic regression test P=0.340 P=0.469 P=0.497 P=0.366 

Cochran-Armitage test P=0.325 

Fisher exact test P=0.500 P=0.661N P=0.357 

All Organs: Mononuclear Cell Leukemia 

Overall rate 14/50 (28%) 19/50 (38%) 29/50 (58%) 18/50 (36%) 

Adjusted rate 37.7% 46.9% 67.4% 43.8% 

Terminal rate 10/32 (31%) 7/26 (27%) 7/20 (35%) 9/31 (29%) 

First incidence (days) 522 400 414 613 

Life table test P=0.281 P=0.136 P<0.001 P=0.277 

Logistic regression test P=0.214 P=0.198 P=0.003 P=0.279 

Cochran-Armitage test P=0.215 

Fisher exact test P=0.198 P=0.002 P=0.260 

All Organs: Benign Neoplasms 

Overall rate 43/50 (86%) 39/50 (78%) 30/50 (60%) 26/50 (52%) 

Adjusted rate 95.5% 95.0% 81.9% 66.1% 

Terminal rate 30/32 (94%) 24/26 (92%) 14/20 (70%) 18/31 (58%) 

First incidence (days) 529 475 506 550 

Life table test P=0.002N P=0.446 P=0.563 P=0.003N 

Logistic regression test P<0.001N P=0.174N P=0.007N P<0.001N 

Cochran-Armitage test P<0.001N 

Fisher exact test P=0.218N P=0.003N P<0.001N 

All Organs: Malignant Neoplasms 

Overall rate 21/50 (42%) 26/50 (52%) 34/50 (68%) 22/50 (44%) 

Adjusted rate 51.1% 60.1% 76.4% 51.6% 

Terminal rate 13/32 (41%) 10/26 (38%) 10/20 (50%) 11/31 (35%) 

First incidence (days) 223 288 414 613 

Life table test P=0.502 P=0.146 P=0.001 P=0.498 

Logistic regression test P=0.461 P=0.205 P=0.013 P=0.496 

Cochran-Armitage test P=0.477 

Fisher exact test P=0.212 P=0.008 P=0.500 
138 

c 

Oxazepam, NTP TR 468 

TABLE B3a
 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 

All Organs: Benign or Malignant Neoplasms 

Overall rate 49/50 (98%) 49/50 (98%) 45/50 (90%) 38/50 (76%) 

Adjusted rate 100.0% 98.0% 90.0% 82.5% 

Terminal rate 32/32 (100%) 25/26 (96%) 15/20 (75%) 23/31 (74%) 

First incidence (days) 223 288 414 550 

Life table test P=0.041N P=0.220 P=0.085 P=0.058N 

Logistic regression test P<0.001N P=0.761N P=0.063N P=0.001N 

Cochran-Armitage test P<0.001N 

Fisher exact test P=0.753N P=0.102N P<0.001N 

(T) Terminal sacrifice a Number of neoplasm-bearing animals/number of animals examined. Denominator is number of animals examined microscopically for adrenal gland, 

clitoral gland, pituitary gland, thyroid gland, and uterus; for other tissues, denominator is number of animals necropsied. b	 Kaplan-Meier estimated neoplasm incidence at the end of the study after adjustment for intercurrent mortality 

Observed incidence at terminal kill 

d	 Beneath the control incidence are the P values associated with the trend test. Beneath the exposed group incidence are the P values corresponding to 

pairwise comparisons between the controls and that exposed group. The life table test regards neoplasms in animals dying prior to terminal kill as being 

(directly or indirectly) the cause of death. The logistic regression test regards these lesions as nonfatal. The Cochran-Armitage and Fisher exact tests 

compare directly the overall incidence rates. For all tests, a negative trend or a lower incidence in an exposed group is indicated by N. e Not applicable; no neoplasms in animal group 
Oxazepam, NTP TR 468 139 

TABLE B3b 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Stop-Exposure Feed Study of Oxazepam 

0 ppm 10,000 ppm 

Adrenal Medulla: Benign, Complex, or Malignant Pheochromocytoma 

Overall ratea 3/50 (6%) 0/0d 

Adjusted rateb 8.9% c Terminal rate 2/32 (6%) 

First incidence (days) 700 

Clitoral Gland: Adenoma 

Overall rate 7/49 (14%) 7/11 (64%)d
 

Adjusted rate 19.4%
 

Terminal rate 4/31 (13%)
 

First incidence (days) 550
 

Clitoral Gland: Adenoma or Carcinoma 

Overall rate 8/49 (16%) 7/11 (64%)d
 

Adjusted rate 22.4%
 

Terminal rate 5/31 (16%)
 

First incidence (days) 550
 

Mammary Gland: Fibroadenoma 

Overall rate 25/50 (50%) 23/50 (46%)
 

Adjusted rate 67.0% 66.7%
 

Terminal rate 20/32 (63%) 14/25 (56%)
 

First incidence (days) 529 562
 

Life table teste P=0.394
 e Logistic regression test P=0.428N 

Fisher exact teste P=0.421N 

Mammary Gland: Fibroadenoma or Adenoma 

Overall rate 26/50 (52%) 23/50 (46%) 

Adjusted rate 67.8% 66.7% 

Terminal rate 20/32 (63%) 14/25 (56%) 

First incidence (days) 529 562 

Life table test P=0.468 

Logistic regression test P=0.340N 

Fisher exact test P=0.345N 

Mammary Gland: Adenoma or Carcinoma 

Overall rate 3/50 (6%) 1/50 (2%) 

Adjusted rate 7.4% 2.1% 

Terminal rate 1/32 (3%) 0/25 (0%) 

First incidence (days) 228 562 

Life table test P=0.327N 

Logistic regression test P=0.466N 

Fisher exact test P=0.309N 

Mammary Gland: Fibroadenoma, Adenoma, or Carcinoma 

Overall rate 27/50 (54%) 23/50 (46%) 

Adjusted rate 68.4% 66.7% 

Terminal rate 20/32 (63%) 14/25 (56%) 

First incidence (days) 228 562 

Life table test P=0.542 

Logistic regression test P=0.346N 

Fisher exact test P=0.274N 
140 Oxazepam, NTP TR 468 

TABLE B3b 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Stop-Exposure Feed Study of Oxazepam 

(continued) 

0 ppm 10,000 ppm 

Pituitary Gland (Pars Distalis): Adenoma 

Overall rate 31/50 (62%) 23/35 (66%) 

Adjusted rate 73.6% 67.3% 

Terminal rate 21/32 (66%) 8/16 (50%) 

First incidence (days) 529 562 

Life table test P=0.438 

Logistic regression test P=0.507 

Fisher exact test P=0.453 

Thyroid Gland (C-cell): Adenoma 

Overall rate 6/50 (12%) 4/50 (8%) 

Adjusted rate 16.5% 13.8% 

Terminal rate 3/32 (9%) 3/25 (12%) 

First incidence (days) 647 562 

Life table test P=0.472N 

Logistic regression test P=0.365N 

Fisher exact test P=0.370N 

Thyroid Gland (C-cell): Adenoma or Carcinoma 

Overall rate 7/50 (14%) 4/50 (8%) 

Adjusted rate 19.4% 13.8% 

Terminal rate 4/32 (13%) 3/25 (12%) 

First incidence (days) 647 562 

Life table test P=0.366N 

Logistic regression test P=0.258N 

Fisher exact test P=0.262N 

Uterus: Stromal Polyp or Stromal Sarcoma 

Overall rate 3/50 (6%) 1/50 (2%) 

Adjusted rate 9.4% 4.0% 

Terminal rate 3/32 (9%) 1/25 (4%) 

First incidence (days) 729 (T) 729 (T) 

Life table test P=0.396N 

Logistic regression test P=0.396N 

Fisher exact test P=0.309N 

All Organs: Mononuclear Cell Leukemia 

Overall rate 14/50 (28%) 15/50 (30%) 

Adjusted rate 37.7% 40.5% 

Terminal rate 10/32 (31%) 6/25 (24%) 

First incidence (days) 522 506 

Life table test P=0.336 

Logistic regression test P=0.507 

Fisher exact test P=0.500 

All Organs: Benign Neoplasms 

Overall rate 43/50 (86%) 38/50 (76%) 

Adjusted rate 95.5% 84.3% 

Terminal rate 30/32 (94%) 18/25 (72%) 

First incidence (days) 529 562 

Life table test P=0.482 

Logistic regression test P=0.092N 

Fisher exact test P=0.154N 
141 

c 

Oxazepam, NTP TR 468 

TABLE B3b 

Statistical Analysis of Primary Neoplasms in Female Rats in the 2-Year Stop-Exposure Feed Study of Oxazepam 

(continued) 

0 ppm	 10,000 ppm 

All Organs: Malignant Neoplasms 

Overall test 21/50 (42%) 17/50 (34%) 

Adjusted rate 51.1% 43.0% 

Terminal rate 13/32 (41%) 6/25 (24%) 

First incidence (days) 223 506 

Life table test P=0.460N 

Logistic regression test P=0.293N 

Fisher exact test P=0.268N 

All Organs: Benign or Malignant Neoplasms 

Overall rate 49/50 (98%) 43/50 (86%) 

Adjusted rate 100.0% 89.5% 

Terminal rate 32/32 (100%) 20/25 (80%) 

First incidence (days) 223 506 

Life table test P=0.515 

Logistic regression test P=0.030N 

Fisher exact test P=0.030N 

(T)Terminal sacrifice 

a Number of neoplasm-bearing animals/number of animals examined. Denominator is number of animals examined microscopically for adrenal gland, 

clitoral gland, pituitary gland, and thyroid gland; for other tissues, denominator is number of animals necropsied. b	 Kaplan-Meier estimated neoplasm incidence at the end of the study after adjustment for intercurrent mortality 

Observed incidence at terminal kill 

d	 Tissue was examined microscopically only when it was observed to be abnormal at necropsy; thus, statistical comparisons with the controls are not 

appropriate. e Beneath the exposed group incidence are the P values corresponding to pairwise comparisons between the controls and the exposed group. The life 

table test regards neoplasms in animals dying prior to terminal kill as being (directly or indirectly) the cause of death. The logistic regression test 

regards these lesions as nonfatal. The Fisher exact test compares directly the overall incidence rates. For all tests, a lower incidence in the exposed 

group is indicated by N. 
142 Oxazepam, NTP TR 468 

TABLE B4a 

Historical Incidence of Mammary Gland Neoplasms in Untreated Female F344/N Ratsa 

Incidence in Controls 

Study Fibroadenoma Fibroadenoma Carcinoma Adenoma or Fibroadenoma, 

or Adenoma Carcinoma Adenoma, or 

Carcinoma 

Historical Incidence at Battelle Columbus Laboratories 

4,4'-Thiobis(6-t-Butyl-m-Cresol) 29/50 31/50 1/50 3/50 32/50 

5,5-Diphenylhydantoin 17/50 18/50 3/50 4/50 21/50 

Ethylene Thiourea 13/50 13/50 0/50 0/50 13/50 

Polybrominated Biphenyls (Firemaster FF-1®) 4/50 4/50 0/50 0/50 4/50 

Manganese (II) Sulfate Monohydrate 19/50 19/50 0/50 0/50 19/50 

Triamterene 19/50 22/50 0/50 4/50 22/50 

Tricresyl Phosphate 15/51 18/51 0/51 3/51 18/51 

Overall Historical Incidence 

Total 524/1,301 (40.3%) 540/1,301 (41.5%) 36/1,301 (2.8%) 60/1,301 (4.6%) 568/1,301 (43.7%) 

Standard deviation 13.1% 13.2% 2.7% 3.2% 13.9% 

Range 8%-58% 8%-62% 0%-8% 0%-10% 8%-64% 

a Data as of 12 May 1995 

TABLE B4b 

Historical Incidence of Pituitary Gland (Pars Distalis) Neoplasms in Untreated Female F344/N Ratsa 

Incidence in Controls 

Study Adenoma Carcinoma Adenoma or 

Carcinoma 

Historical Incidence at Battelle Columbus Laboratories 

4,4'-Thiobis(6-t-Butyl-m-Cresol) 27/49 0/49 27/49 

5,5-Diphenylhydantoin 25/50 1/50 26/50 

Ethylene Thiourea 24/50 0/50 24/50 

Polybrominated Biphenyls (Firemaster FF-1®) 21/50 0/50 21/50 

Manganese (II) Sulfate Monohydrate 23/50 0/50 23/50 

Triamterene 21/50 0/50 21/50 

Tricresyl Phosphate 30/51 0/51 30/51 

Overall Historical Incidence 

Total 666/1,290 (51.6%) 14/1,290 (1.1%) 680/1,290 (52.7%) 

Standard deviation 12.5% 1.4% 12.7% 

Range 30%-74% 0%-4% 30%-76% 

a Data as of 12 May 1995 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 143 

TABLE B5 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Feed Study of Oxazepama 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Disposition Summary 

Animals initially in study 50 50 50 50 50 

Early deaths

 Accidental death 1

 Moribund 11 18 18 16 19

 Natural deaths 6 6 12 3 6 

Survivors

 Terminal sacrifice 32 26 20 31 25 

Animals examined microscopically 50 50 50 50 50 

Alimentary System 

Esophagus (50) (50) (50) (49) (1) 

Periesophageal tissue, necrosis 1 (100%) 

Intestine large, colon (50) (48) (49) (50) 

Parasite metazoan 2 (4%) 2 (4%) 2 (4%) 2 (4%) 

Intestine large, rectum (50) (49) (49) (50) 

Cyst 1 (2%) 

Parasite metazoan 2 (4%) 2 (4%) 1 (2%) 

Intestine small, duodenum (50) (49) (47) (49) (47) 

Ulcer 2 (4%) 

Serosa, inflammation 1 (2%) 

Intestine small, jejunum (46) (48) (47) (48) (1) 

Parasite metazoan 1 (2%) 

Ulcer 1 (100%) 

Liver (50) (50) (50) (50) (49) 

Basophilic focus 44 (88%) 41 (82%) 28 (56%) 26 (52%) 16 (33%) 

Clear cell focus 6 (12%) 3 (6%) 11 (22%) 22 (44%) 

Degeneration, cystic 2 (4%) 

Degeneration, fatty 1 (2%) 2 (4%) 

Eosinophilic focus 17 (34%) 18 (36%) 4 (8%) 11 (22%) 11 (22%) 

Hepatodiaphragmatic nodule 12 (24%) 2 (4%) 4 (8%) 5 (10%) 6 (12%) 

Inflammation, granulomatous 1 (2%) 2 (4%) 3 (6%) 

Mixed cell focus 5 (10%) 15 (30%) 7 (14%) 3 (6%) 2 (4%) 

Necrosis, focal 2 (4%) 1 (2%) 

Centrilobular, atrophy 1 (2%) 

Centrilobular, necrosis 1 (2%) 2 (4%) 1 (2%) 

Hepatocyte, centrilobular, hypertrophy 10 (20%) 31 (62%) 

Mesentery (10) (9) (4) (6) (13) 

Accessory spleen 1 (10%) 

Fat, necrosis 8 (80%) 9 (100%) 4 (100%) 6 (100%) 13 (100%) 

Pancreas (50) (50) (49) (49) 

Acinus, atrophy 6 (12%) 6 (12%) 1 (2%) 8 (16%) 

Stomach, forestomach (50) (50) (50) (50) (50) 

Abscess 1 (2%) 

Erosion 2 (4%) 

Foreign body 2 (4%) 

Inflammation, chronic 3 (6%) 

Inflammation, chronic active 1 (2%) 5 (10%) 13 (26%) 3 (6%) 5 (10%) 

Inflammation, granulomatous 1 (2%) 1 (2%) 

Ulcer 1 (2%) 2 (4%) 9 (18%) 6 (12%) 4 (8%) 

Epithelium, hyperplasia 2 (4%) 6 (12%) 16 (32%) 5 (10%) 5 (10%) 

a Number of animals examined microscopically at the site and the number of animals with lesion 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

144 Oxazepam, NTP TR 468 

TABLE B5
 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Alimentary System (continued) 

Stomach, glandular (50) (50) (50) (50) (49) 

Erosion 4 (8%) 7 (14%) 2 (4%) 

Inflammation, chronic active 1 (2%) 

Mineralization 1 (2%) 1 (2%) 2 (4%) 

Ulcer 2 (4%) 3 (6%) 5 (10%) 4 (8%) 

Serosa, inflammation 1 (2%) 

Cardiovascular System 

Blood vessel (50) (50) (50) (49) 

Aorta, mineralization 1 (2%) 

Heart (50) (50) (49) (49) 

Atrium, thrombosis 1 (2%) 

Myocardium, degeneration 32 (64%) 34 (68%) 35 (71%) 32 (65%) 

Myocardium, fibrosis, focal 2 (4%) 

Myocardium, mineralization 1 (2%) 

Pericardium, inflammation, chronic 1 (2%) 

Valve, inflammation, chronic 1 (2%) 

Endocrine System 

Adrenal cortex (50) (50) (50) (50) (2) 

Degeneration 1 (2%) 

Hemorrhage 1 (2%) 

Hyperplasia, diffuse 1 (2%) 

Hyperplasia, focal 9 (18%) 8 (16%) 5 (10%) 4 (8%) 

Hypertrophy, focal 2 (4%) 1 (2%) 

Pigmentation, hemosiderin 1 (2%) 1 (2%) 

Adrenal medulla (50) (50) (50) (50) 

Degeneration 1 (2%) 

Hyperplasia 8 (16%) 3 (6%) 1 (2%) 4 (8%) 

Islets, pancreatic (50) (50) (49) (49) 

Hyperplasia 2 (4%) 1 (2%) 1 (2%) 

Pituitary gland (50) (50) (50) (50) (35) 

Angiectasis 2 (4%) 

Cyst 1 (2%) 2 (6%) 

Pars distalis, angiectasis 1 (2%) 

Pars distalis, cyst 5 (10%) 2 (4%) 1 (2%) 3 (6%) 2 (6%) 

Pars distalis, degeneration, cystic 1 (2%) 3 (6%) 5 (14%) 

Pars distalis, hyperplasia 4 (8%) 5 (10%) 3 (6%) 8 (16%) 1 (3%) 

Pars distalis, vacuolization cytoplasmic,

 focal 1 (3%) 

Thyroid gland (50) (50) (48) (49) (50) 

Ultimobranchial cyst 1 (2%) 

C-cell, hyperplasia 40 (80%) 43 (86%) 35 (73%) 42 (86%) 43 (86%) 

Follicle, cyst 1 (2%) 2 (4%) 2 (4%) 1 (2%) 

General Body System 

Peritoneum (1) 

Inflammation, granulomatous 1 (100%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Oxazepam, NTP TR 468 145 

TABLE B5
 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Genital System 

Clitoral gland (49) (50) (50) (50) (11) 

Cyst 1 (2%) 

Hyperplasia 1 (2%) 

Inflammation, chronic 1 (2%) 

Inflammation, chronic active 1 (2%) 

Inflammation, granulomatous 1 (2%) 

Inflammation, suppurative 1 (9%) 

Duct, cyst 1 (2%) 4 (8%) 6 (12%) 2 (4%) 3 (27%) 

Ovary (50) (50) (50) (50) (4) 

Cyst 5 (10%) 6 (12%) 5 (10%) 6 (12%) 4 (100%) 

Uterus (50) (50) (50) (50) (5) 

Inflammation, chronic 1 (2%) 

Inflammation, suppurative 1 (20%) 

Cervix, cyst 2 (4%) 1 (2%) 1 (2%) 1 (20%) 

Cervix, inflammation, suppurative 1 (20%) 

Cervix, myometrium, hyperplasia 2 (4%) 1 (20%) 

Endometrium, hyperplasia, cystic 1 (2%) 1 (2%) 1 (2%) 

Hematopoietic System 

Bone marrow (50) (50) (50) (50) 

Necrosis 1 (2%) 

Lymph node (4) (2) (9) (3) (4) 

Lumbar, ectasia 1 (11%) 

Mediastinal, pigmentation, hemosiderin 1 (33%) 

Pancreatic, inflammation, granulomatous 1 (11%) 

Renal, ectasia 1 (25%) 

Lymph node, mandibular (50) (48) (48) (49) (3) 

Ectasia 1 (2%) 

Lymph node, mesenteric (50) (50) (50) (49) (2) 

Ectasia 1 (2%) 

Inflammation, acute 1 (2%) 

Spleen (50) (50) (50) (49) (12) 

Fibrosis 1 (2%) 2 (4%) 2 (4%) 2 (17%) 

Hematopoietic cell proliferation 3 (6%) 2 (4%) 3 (6%) 1 (2%) 

Inflammation, granulomatous 1 (2%) 1 (2%) 1 (8%) 

Pigmentation, hemosiderin 25 (50%) 27 (54%) 13 (26%) 22 (45%) 

Lymphoid follicle, atrophy 2 (4%) 

Integumentary System 

Mammary gland (49) (49) (49) (50) (23) 

Hyperplasia, cystic 2 (4%) 3 (6%) 1 (2%) 1 (2%) 1 (4%) 

Metaplasia, squamous 1 (2%) 

Skin (50) (50) (50) (50) (6) 

Hyperkeratosis 1 (17%) 

Ulcer 2 (4%) 

Subcutaneous tissue, edema 1 (2%) 

Subcutaneous tissue, inflammation,

 chronic 1 (2%) 

Subcutaneous tissue, inflammation,

 suppurative 1 (17%) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

146 Oxazepam, NTP TR 468 

TABLE B5
 

Summary of the Incidence of Nonneoplastic Lesions in Female Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 625 ppm 2,500 ppm 5,000 ppm 10,000 ppm 

(Stop-Exposure) 

Musculoskeletal System 

Bone (50) (50) (50) (50) (1) 

Hyperostosis 1 (2%) 2 (4%) 

Inflammation, chronic 1 (100%) 

Osteopetrosis 3 (6%) 

Cranium, hyperostosis, focal 1 (2%) 

Nervous System 

Brain (50) (50) (50) (50) 

Hydrocephalus 7 (14%) 12 (24%) 3 (6%) 3 (6%) 

Cerebellum, mineralization 1 (2%) 

Cerebrum, degeneration, focal 1 (2%) 

Hypothalamus, hemorrhage 2 (4%) 2 (4%) 1 (2%) 

Respiratory System 

Lung (50) (50) (49) (49) 

Congestion 1 (2%) 

Infiltration cellular, mast cell 1 (2%) 

Infiltration cellular, histiocyte 2 (4%) 

Inflammation, granulomatous 2 (4%) 2 (4%) 5 (10%) 8 (16%) 

Alveolar epithelium, hyperplasia 3 (6%) 4 (8%) 1 (2%) 3 (6%) 

Interstitium, inflammation, chronic 1 (2%) 2 (4%) 2 (4%) 

Serosa, inflammation, chronic 1 (2%) 

Nose (50) (50) (50) (50) 

Inflammation, suppurative 5 (10%) 2 (4%) 6 (12%) 4 (8%) 

Special Senses System 

Eye (2) (1) (1) (2) 

Choroid, inflammation, chronic 1 (100%) 

Lens, cataract 2 (100%) 1 (100%) 2 (100%) 

Urinary System 

Kidney (50) (50) (50) (50) (1) 

Inflammation, chronic active 1 (2%) 

Nephropathy 32 (64%) 43 (86%) 41 (82%) 48 (96%) 1 (100%) 

Pigmentation, lipofuscin 2 (4%) 

Renal tubule, cyst 1 (2%) 1 (2%) 1 (2%) 

Renal tubule, vacuolization cytoplasmic 1 (2%) 

Urinary bladder (48) (49) (49) (50) 

Inflammation, chronic active 1 (2%) 

Transitional epithelium, hyperplasia 1 (2%) 1 (2%) 
147 

APPENDIX C
 

GENETIC TOXICOLOGY
 

SALMONELLA MUTAGENICITY TEST PROTOCOL ........................................ 148
 

CHINESE HAMSTER OVARY CELL CYTOGENETICS PROTOCOLS .............................. 148
 

MOUSE PERIPHERAL BLOOD MICRONUCLEUS TEST PROTOCOL ............................. 149
 

RESULTS ................................................................ 150
 

TABLE C1 Mutagenicity of Oxazepam in Salmonella typhimurium ....................... 151
 

TABLE C2 Induction of Sister Chromatid Exchanges in Chinese Hamster Ovary Cells 

by Oxazepam ................................................... 153
 

TABLE C3 Induction of Chromosomal Aberrations in Chinese Hamster Ovary Cells 

by Oxazepam ................................................... 154
 

TABLE C4 Frequency of Micronuclei in Peripheral Blood Erythrocytes 

of Mice Following Treatment with Oxazepam by Feed for 14 Weeks .............. 154
 
 

148 Oxazepam, NTP TR 468 

GENETIC TOXICOLOGY
 

SALMONELLA MUTAGENICITY TEST PROTOCOL 

Testing was performed as reported by Zeiger et al. (1992). Oxazepam was sent to the laboratory as a coded 

aliquot from Radian Corporation (Austin, TX). Oxazepam was incubated with the Salmonella typhimurium 

tester strains TA97, TA98, TA100, TA102, and TA1535 either in buffer or S9 mix (metabolic activation 

enzymes and cofactors from Aroclor 1254-induced male Sprague-Dawley rat or Syrian hamster liver) for 

20 minutes at 37E C. Top agar supplemented with L-histidine and d-biotin was added, and the contents of 

the tubes were mixed and poured onto the surfaces of minimal glucose agar plates. Histidine-independent 

mutant colonies arising on these plates were counted following incubation for 2 days at 37E C. 

Each trial consisted of triplicate plates of concurrent positive and negative controls and at least three doses of 

oxazepam. The high dose was limited by solubility and toxicity. 

In this assay, a positive response is defined as a reproducible, dose-related increase in histidine-independent 

(revertant) colonies in any one strain/activation combination. An equivocal response is defined as an 

increase in revertants that is not dose related, not reproducible, or not of sufficient magnitude to support a 

determination of mutagenicity. A negative response is obtained when no increase in revertant colonies is 

observed following chemical treatment. No minimum percentage or fold increase is required for a chemical 

to be judged positive or weakly positive. 

CHINESE HAMSTER OVARY CELL CYTOGENETICS PROTOCOLS 

Testing was performed as reported by Galloway et al. (1987). Oxazepam was sent to the laboratory as a 

coded aliquot by Radian Corporation. Oxazepam was tested in cultured Chinese hamster ovary (CHO) cells 

for induction of sister chromatid exchanges (SCEs) and chromosomal aberrations (Abs), both in the presence 

and absence of Aroclor 1254-induced male Sprague-Dawley rat liver S9 and cofactor mix. Cultures were 

handled under gold lights to prevent photolysis of bromodeoxyuridine-substituted DNA. Each test consisted 

of concurrent solvent and positive controls and of at least three doses of oxazepam. The high dose was 

limited by toxicity. A single flask per dose was used, and tests yielding positive results were repeated. 

Sister Chromatid Exchange Test: In the SCE test without S9, CHO cells were incubated for 26 hours with 

oxazepam in McCoy’s 5A medium. Bromodeoxyuridine (BrdU) was added 2 hours after culture initiation. 

After 26 hours, the medium containing oxazepam was removed and replaced with fresh medium plus BrdU 

and Colcemid, and incubation was continued for 2 hours. Cells were then harvested by mitotic shake-off, 

fixed, and stained with Hoechst 33258 and Giemsa. In the SCE test with S9, cells were incubated with 

oxazepam, serum-free medium, and S9 for 2 hours. The medium was then removed and replaced with 

medium containing serum and BrdU and no oxazepam, and incubation proceeded for an additional 26 hours, 

with Colcemid present for the final 2 hours. Harvesting and staining were the same as for cells treated 

without S9. All slides were scored blind, and those from a single test were read by the same person. Fifty 

second-division metaphase cells were scored for frequency of SCEs/cell from each dose level. Because 

significant chemical-induced cell cycle delay was seen at the 50 μg/mL dose without S9, incubation time was 

lengthened to ensure a sufficient number of scorable (second-division metaphase) cells. 

Statistical analyses were conducted on the slopes of the dose-response curves and the individual dose points 

(Galloway et al., 1987). An SCE frequency 20% above the concurrent solvent control value was chosen as a 

statistically conservative positive response. The probability of this level of difference occurring by chance at 

one dose point is less than 0.01; the probability for such a chance occurrence at two dose points is less than 

0.001. An increase of 20% or greater at any single dose was considered weak evidence of activity; increases 
 

Oxazepam, NTP TR 468 149 

at two or more doses resulted in a determination that the trial was positive. A statistically significant trend 

(P#0.05) in the absence of any responses reaching 20% above background led to a call of equivocal. 

Chromosomal Aberrations Test: In the Abs test without S9, cells were incubated in McCoy’s 5A medium 

with oxazepam for 12 hours; Colcemid was added and incubation continued for 2 hours. The cells were then 

harvested by mitotic shake-off, fixed, and stained with Giemsa. For the Abs test with S9, cells were treated 

with oxazepam and S9 for 2 hours, after which the treatment medium was removed and the cells were 

incubated for 10 hours in fresh medium, with Colcemid present for the final 2 hours. Cells were harvested 

in the same manner as for the treatment without S9. 

Cells were selected for scoring on the basis of good morphology and completeness of karyotype 

(21 ± 2 chromosomes). All slides were scored blind and those from a single test were read by the same 

person. Two hundred first-division metaphase cells were scored at each dose level. Classes of aberrations 

included simple (breaks and terminal deletions), complex (rearrangements and translocations), and other 

(pulverized cells, despiralized chromosomes, and cells containing 10 or more aberrations). 

Chromosomal aberration data are presented as percentage of cells with aberrations. To arrive at a statistical 

call for a trial, analyses were conducted on both the dose response curve and individual dose points. For a 

single trial, a statistically significant (P#0.05) difference for one dose point and a significant trend (P#0.015) 

were considered weak evidence for a positive response; significant differences for two or more doses 

indicated the trial was positive. A positive trend test in the absence of a statistically significant increase at 

any one dose resulted in an equivocal call (Galloway et al., 1987). Ultimately, the trial calls were based on 

a consideration of the statistical analyses as well as the biological information available to the reviewers. 

MOUSE PERIPHERAL BLOOD MICRONUCLEUS TEST PROTOCOL 

A detailed discussion of this assay is presented in MacGregor et al. (1990). At the end of a 14-week study 

(NTP, 1993), peripheral blood samples were obtained from male and female B6C3F1 mice from each dose

group and smears were immediately prepared and fixed in absolute methanol. The methanol-fixed slides 

were stained with a chromatin-specific fluorescent dye mixture of Hoechst 33258/pyronin Y (MacGregor 

et al., 1983), and coded. Slides were scanned to determine the frequency of micronuclei in 

10,000 normochromatic erythrocytes (NCEs) in each of 10 animals per dose group. 

The results were tabulated as the mean of the pooled results from all animals within a treatment group plus or 

minus the standard error of the mean. The frequency of micronucleated cells among NCEs was analyzed by 

a statistical software package that tested for increasing trend over dose groups with a one-tailed CochranArmitage trend test, followed by pairwise comparisions between each dosed group and the control group 

(Margolin et al., 1990). In the presence of excess binomial variation, as detected by a binomial dispersion 

test, the binomial variance of the Cochran-Armitage test was adjusted upward in proportion to the excess 

variation. In the micronucleus test, an individual trial is considered positive if the trend test P value is less 

than or equal to 0.025 or if the P value for any single dose group is less than or equal to 0.025 divided by 

the number of dose groups. A final call of positive for micronucleus induction is preferably based on 

reproducibly positive trial (as noted above). Results of the 14-week studies were accepted without repeat 

tests because additional test data could not be obtained. Ultimately, the final call is determined by the 

scientific staff after considering the results of statistical analyses, the reproducibility of any effects observed, 

and the magnitude of those effects. 

RESULTS 

Oxazepam (3 to 3,333 μg/plate) did not induce mutations in S. typhimurium strains TA97, TA98, TA100, 

TA102, or TA1535 when tested in a preincubation protocol with or without Aroclor 1254-induced male 
150 Oxazepam, NTP TR 468 

Sprague-Dawley rat or Syrian hamster liver S9 (Table C1). In cytogenetic tests with cultured CHO cells, 

oxazepam did not induce sister chromatid exchanges (Table C2) or chromosomal Abs (Table C3), with or 

without S9. Cell cycle delay was noted at the 50 Fg/mL dose in the SCE test without S9; harvest time was 

extended to allow accumulation of sufficient second-division metaphase cells for analysis. Peripheral blood 

samples obtained from B6C3F mice in a 14-week toxicity study were analyzed for frequency of 1 

micronucleated NCEs; no increase in frequencies of micronucleated NCEs was observed in any of the dose 

groups (Table C4). 
Oxazepam, NTP TR 468 151 

TABLE C1 

Mutagenicity of Oxazepam in Salmonella typhimuriuma

 Revertants/plateb 

Strain Dose 

(μg/plate) 

-S9 + hamster S9 

10% 30% 10% 

+ rat S9 

30% 

TA102 

0 

3 

10 

33 

100 

333 

1,000 

1,666 

3,333 

131 ± 2.6 

136 ± 5.7 

128 ± 10.7 

139 ± 1.8 

130 ± 8.3 

43 ± 3.9c 

155 ± 12.4 

213 ± 5.7 

223 ± 15.0 

196 ± 10.0 

170 ± 2.7 

318 ± 1.3 

103 ± 21.5c 

172 ± 1.2c 

341 ± 23.3 

295 ± 8.1 

340 ± 24.6 

358 ± 25.0 

166 ± 28.6 

197 ± 11.5 

216 ± 9.5 

208 ± 6.4 

204 ± 14.3 

375 ± 19.9 

102c 

133 ± 17.3c 

443 ± 24.8 

403 ± 17.1 

436 ± 38.4 

413 ± 22.0 

Trial summary 

Positive controld Negative 

676 ± 9.5 

Negative 

879 ± 17.9 

Negative 

2,127 ± 104.3 

Negative 

1,291 ± 49.3 

Negative 

1,104 ± 125.0 

TA100 

0 

3 

10 

33 

100 

333 

1,000 

1,666 

159 ± 8.0 

118 ± 4.6 

128 ± 5.5 

137 ± 14.0 

139 ± 8.9 

115 ± 9.7 

102 ± 5.8 

146 ± 1.9 

144 ± 2.3 

159 ± 17.2 

137 ± 15.4 

141 ± 2.9 

145 ± 8.1 

145 ± 9.1 

146 ± 2.1 

113 ± 8.7 

93 ± 2.8 

100 ± 14.9 

161 ± 10.0 

160 ± 9.0 

157 ± 8.9 

156 ± 8.9 

133 ± 7.0 

126 ± 2.5 

135 ± 13.2 

149 ± 2.5 

137 ± 7.4 

127 ± 1.2 

134 ± 4.8 

134 ± 4.1 

Trial summary 

Positive control 

Negative 

316 ± 3.5 

Negative 

445 ± 11.7 

Negative 

462 ± 31.2 

Negative 

599 ± 23.1 

Negative 

244 ± 6.7 

TA1535 

0 

3 

10 

33 

100 

333 

1,000 

1,666 

3,333 

20 ± 1.5 

20 ± 2.3 

19 ± 1.5 

19 ± 2.9 

15 ± 4.2 

18 ± 2.0 

8 ± 0.9 

8 ± 3.0 

11 ± 2.0 

8 ± 1.0 

9 ± 1.3 

8 ± 1.2e 

12 ± 2.9 

10 ± 2.0 

11 ± 3.4 

9 ± 2.5 

8 ± 0.3 

5 ± 0.7e 

12 ± 1.7 

10 ± 2.0 

11 ± 1.5 

11 ± 0.6 

9 ± 0.7 

7 ± 1.5e 

14 ± 2.1 

14 ± 0.3 

15 ± 1.5 

15 ± 1.9 

12 ± 2.7 

9 ± 0.6e 

Trial summary 

Positive control 

Negative 

332 ± 10.2 

Negative 

180 ± 18.4 

Negative 

340 ± 22.8 

Negative 

214 ± 27.7 

Negative 

206 ± 4.7 
152 

c 

Oxazepam, NTP TR 468 

TABLE C1
 

Mutagenicity of Oxazepam in Salmonella typhimurium (continued)
 

Revertants/plate 

Strain Dose -S9 +hamster S9 +rat S9 

(μg/plate) 10% 30% 10% 30% 

TA97 

0 184 ± 6.1 179 ± 3.0 164 ± 8.3 206 ± 1.5 209 ± 6.1 

3 193 ± 7.4 

10 182 ± 2.6 163 ± 8.2	 204 ± 4.2 

33 180 ± 10.5 163 ± 5.0 183 ± 6.9 203 ± 0.9 191 ± 9.1 

100 160 ± 7.3 167 ± 9.0 187 ± 12.4 200 ± 3.1 150 ± 6.2 

333 148 ± 12.7 175 ± 11.0 174 ± 14.0 198 ± 3.0 162 ± 17.4 

1,000	 172 ± 17.3 168 ± 9.1 168 ± 5.8 184 ± 16.8 c c 3,333	 107 ± 5.7 139 ± 11.2 

Trial summary Negative Negative Negative Negative Negative 

Positive control 403 ± 11.1 463 ± 15.8 368 ± 24.9 449 ± 10.1 454 ± 25.6 

TA98 

0 18 ± 2.3 28 ± 2.0 19 ± 0.9 19 ± 1.5 23 ± 1.2 

3 15 ± 2.2 

10 16 ± 2.0 

33 19 ± 2.3 18 ± 0.6 27 ± 4.3 24 ± 3.0 28 ± 2.2 

100 20 ± 0.7 21 ± 2.1 27 ± 4.1 22 ± 3.7 33 ± 2.6 

333 17 ± 1.7 20 ± 0.3 23 ± 3.3 23 ± 4.6 31 ± 4.7 

1,000	 20 ± 2.3 34 ± 2.3 14 ± 0.7 23 ± 1.7 e e 1,666	 17 ± 0.6 27 ± 1.5 22 ± 3.5 21 ± 2.3 

Trial summary Negative Negative Negative Negative Negative 

Positive control 423 ± 27.7 523 ± 10.6 495 ± 21.7 202 ± 10.9 104 ± 5.9 

a Study performed at SRI International. A detailed protocol is presented in Zeiger et al. (1992). b Revertants are presented as mean ± standard error from three plates. 

Slight toxicity d	 The positive controls in the absence of metabolic activation were sodium azide (TA100 and TA1535), 9-aminoacridine (TA97), 

4-nitro-o-phenylenediamine (TA98), and mytomycin C (TA102). The positive control for metabolic activation with all strains was 

2-aminoanthracene. e Precipitate on plate 
 

153 

c 

Oxazepam, NTP TR 468 

TABLE C2 

Induction of Sister Chromatid Exchanges in Chinese Hamster Ovary Cells by Oxazepama 

Total No. of SCEs/ Relative 

Dose Cells Chromo- No. of Chromo- SCEs/ Hrs Change of SCEs/ 

Compound (μg/mL) Scored somes SCEs some Cell in BrdU Chromosomeb 

(%) 

-S9 

Summary: Negative 

Dimethylsulfoxide	 50 1,049 424 0.40 8.5 26.0 

50 1,045 393 0.37 7.9 31.0c 

Mitomycin-C 0.001	 50 1,048 579 0.55 11.6 26.0 46.91 

0.004 10 210 223 1.06 22.3 26.0 182.37 

Oxazepam	 5 50 1,048 448 0.42 9.0 26.0 13.67 

17 50 1,048 428 0.40 8.6 26.0 8.59 c 50 50 1,048 449 0.42 9.0 31.0 13.92 

P=0.061d 

+S9 

Summary: Negative 

Dimethylsulfoxide 50 1,046 402 0.38 8.0 26.0 

Cyclophosphamide 0.125 50 1,043 579 0.55 11.6 26.0 44.44 

0.500 10 209 205 0.98 20.5 26.0 155.22 

Oxazepam 5 50 1,048 452 0.43 9.0 26.0 12.22 

17 50 1,050 460 0.43 9.2 26.0 13.99 

50 50 1,048 445 0.42 8.9 26.0 10.48 

P=0.075 

a Study performed at Sitek Research Laboratories. A detailed description of the protocol is presented in Galloway et al. (1987). 

SCE=sister chromatid exchange; BrdU=bromodeoxyuridine b	 SCEs/chromosome in treated cells versus SCEs/chromosome in solvent control cells 

Because oxazepam induced a delay in the cell division cycle, harvest time was extended to maximize the number of second-division 

metaphase cells available for analysis. d	 Significance of SCEs/chromosome tested by the linear regression trend test versus log of the dose 
154 Oxazepam, NTP TR 468 

TABLE C3 

Induction of Chromosomal Aberrations in Chinese Hamster Ovary Cells by Oxazepama 

-S9 +S9 

Dose Total Cells No. of Abs/ Cells with Dose Total Cells No. of Abs/ Cells with 

(μg/mL) Scored Abs Cell Abs (%) (μg/mL) Scored Abs Cell Abs (%) 

Harvest time: 14.0 hours 

Summary: Negative 

Harvest time: 12.0 hours 

Summary: Negative 

Dimethylsulfoxide 

200 5 0.03 1.0 

Dimethylsulfoxide 

200 1 0.01 0.5 

Mitomycin-C 

0.4 25 9 0.36 36.0 

Cyclophosphamide 

20 25 12 0.48 32.0 

Oxazepam 

25 

54 

116 

200 

200 

200 

1 

3 

0 

0.01 

0.02 

0.00 

0.5 

1.0 

0.0 

Oxazepam 

43 

93 

200 

200 

200 

200 

0 

3 

2 

0.00 

0.02 

0.01 

0.0 

1.5 

1.0 

P=0.842b P=0.135 

a Study performed at Sitek Research Laboratories. A detailed description of the protocol is presented in Galloway et al. (1987). 

Abs=aberrations 

b Significance of percent cells with aberrations tested by the linear regression trend test versus log of the dose 

TABLE C4 

Frequency of Micronuclei in Peripheral Blood Erythrocytes of Mice Following Treatment 

with Oxazepam by Feed for 14 Weeksa 

Dose Number of Mice Micronucleated 

(ppm) with Erythrocytes Scored NCE Cellsb (%) 

Male 0 10 0.082 ± 0.008 

625 10 0.081 ± 0.009 

1,250 10 0.078 ± 0.007 

2,500 10 0.085 ± 0.010 

5,000 10 0.074 ± 0.008 

10,000 10 0.069 ± 0.007 

P=0.899c 

Female 0 10 0.042 ± 0.006 

625 10 0.039 ± 0.005 

1,250 10 0.034 ± 0.007 

2,500 10 0.031 ± 0.005 

5,000 10 0.042 ± 0.005 

10,000 10 0.043 ± 0.007 

P=0.194 

a Study was performed at SRI International. NCE=normochromatic erythrocyte b Mean ± standard error 

Significance of percent micronucleated cells tested by the one-tailed trend test (Margolin et al., 1990); significant at P#0.025 c 
155 

APPENDIX D
 

CHEMICAL CHARACTERIZATION
 

AND DOSE FORMULATION STUDIES
 

PROCUREMENT AND CHARACTERIZATION OF OXAZEPAM ................................... 156
 

PREPARATION AND ANALYSIS OF DOSE FORMULATIONS ................................... 157
 

FIGURE D1 Infrared Absorption Spectrum of Oxazepam ............................... 158
 

FIGURE D2 Nuclear Magnetic Resonance Spectrum of Oxazepam ......................... 159
 

TABLE D1 Preparation and Storage of Dose Formulations
 

in the 2-Year Feed Study of Oxazepam ................................... 160
 

TABLE D2 Analysis of Dose Formulations Administered to Rats
 

in the 2-Year Feed Study of Oxazepam ................................... 161
 
156 Oxazepam, NTP TR 468 

CHEMICAL CHARACTERIZATION 

AND DOSE FORMULATION STUDIES 

PROCUREMENT AND CHARACTERIZATION OF OXAZEPAM 

Oxazepam was obtained from Roussel Corporation (Englewood Cliffs, NJ) in one lot (86017.01), which was 

used during the 2-year study. Identity, purity, and stability analyses were conducted by the analytical 

chemistry laboratory, Midwest Research Institute (Kansas City, MO). Reports on analyses performed in 

support of the oxazepam studies are on file at the National Institute of Environmental Health Sciences. 

Initially, comparisons were made between samples from the two shipping containers of lot 86017.01. The 

samples were blended for 15 minutes before being analyzed by high-performance liquid chromatography 

(HPLC) using the following system: Hewlett-Packard RP-18 column using a solvent system consisting of 

A) water containing 1% glacial acetic acid and B) methanol containing 1% glacial acetic acid, with a solvent 

ratio of A:B (50:50), at a flow rate of 1 mL/minute. Detection was with ultraviolet light at 254 nm. Results 

indicated that the two subbatches were identical within the limits of experimental error. 

The chemical, a white, powdered solid, was identified as oxazepam by infrared, ultraviolet/visible, and 

nuclear magnetic resonance spectroscopy. All spectra were consistent with the literature spectra (Florey, 

1974) of oxazepam. The infrared and nuclear magnetic resonance spectra are presented in Figures D1 and 

D2. The observed melting point of 204.5E C was consistent with a literature reference (Merck Index, 1989), 

although the sample decomposed upon heating. 

The purity of oxazepam was determined by elemental analyses, Karl Fischer water analysis, functional group 

titration for phenol, thin-layer chromatography (TLC), and HPLC. Functional group titration was performed 

by dissolving a sample in dimethylformamide and titrating with 0.1 N tetrabutylammonium hydroxide. The 

titration was monitored potentiometrically with a glass indicating electrode and a calomel reference electrode 

containing methanolic 1 M tetrabutylammonium chloride. TLC was performed on Silica Gel 60 F-254 plates 

with two solvent systems: 1) chloroform:methanol (10:1) and 2) ethyl acetate: methanol:glacial acetic acid 

(80:20:10). Anthracene in methanol was used as an internal standard. Visualization was accomplished with 

ultraviolet light (254 and 366 nm) and a spray of 37% formaldehyde solution in concentrated sulfuric acid 

followed by heating for 5 to 10 minutes at 120E C. HPLC was performed with the system described in the 

subbatch comparison. 

Elemental analyses for carbon, hydrogen, nitrogen, and chlorine were in agreement with the theoretical 

values for oxazepam. Karl Fischer water analysis indicated 0.026% ± 0.001% water. Functional group 

titration indicated a purity of 101.4% ± 0.5%. TLC analysis using system 1 indicated a major spot and one 

trace impurity; using system 2, a major spot was observed. HPLC resolved a major peak with no impurity 

peaks with areas 0.1% or greater relative to the major peak. Major peak comparison between this lot and a 

United States Pharmacopeia XXI (USP) oxazepam standard indicated a purity of 103% ± 1% for 

lot 86017.01 relative to the reference standard. The overall purity of lot 86017.01 was determined to be 

greater than 99%. 

Accelerated stability studies of the bulk chemical were performed by the analytical chemistry laboratory. 

HPLC was performed using the system described above except with a solvent ratio of 35:65. These studies 

indicated that oxazepam was stable as a bulk chemical for 2 weeks when stored protected from light at 

temperatures up to 60E C. To ensure the stability during the 2-year study, the bulk chemical was stored at 

room temperature, protected from light, in metal cans or amber glass bottles. The stability of the bulk 

chemical was monitored periodically at the study laboratory with the HPLC system described above. No 

degradation of the bulk chemical was observed. 
Oxazepam, NTP TR 468 157 

PREPARATION AND ANALYSIS OF DOSE FORMULATIONS 

The dose formulations were prepared every 2 weeks by mixing oxazepam with feed (Table D1). Mixtures 

were made by preparing an oxazepam/feed premix by hand and then blending the premix with feed in a 

Patterson-Kelly twin-shell blender for 15 minutes, using an intensifier bar for the initial 5 minutes. 

Formulations were stored in polyethylene bags inside polypropylene buckets at 5E C, protected from light, 

for up to 21 days. 

Homogeneity and stability studies of a 500 ppm dose formulation were performed by the analytical chemistry 

laboratory. Samples were extracted with methanol, centrifuged, and mixed with internal standard solution 

(acetophenone in methanol). The samples were then mixed with additional methanol and further diluted with 

deionized water. HPLC was performed with a Burdick and Jackson C18 column with a mobile phase of 

water:methanol:glacial acetic acid (43:57:1) at a flow rate of 1 mL/minute and ultraviolet detection at 

254 nm. Homogeneity was confirmed, and the dose formulation was determined to be stable for at least 

3 weeks when stored protected from light at 5E C. 

Periodic analyses of the dose formulations of oxazepam were conducted at the study laboratory using HPLC. 

Dose formulations were analyzed every 8 weeks during the study; animal room samples were analyzed 

initially and twice a year thereafter (Table D2). All 50 dose formulations were within 10% of the target 

concentrations; 89% (17/19) of the animal room samples analyzed were within 10% of the target 

concentrations. One animal room sample was 12% greater than the theoretical value; this was attributed to a 

difference between the standard curves for the dose formulation and animal room sample analyses. 
158
 Oxazepam, NTP TR 468
 

FIGURE D1 

Infrared Absorption Spectrum of Oxazepam 
Oxazepam, NTP TR 468
 159 

FIGURE D2 

Nuclear Magnetic Resonance Spectrum of Oxazepam 
160 

86017.01 

Oxazepam, NTP TR 468 

TABLE D1 

Preparation and Storage of Dose Formulations in the 2-Year Feed Study of Oxazepam 

Preparation 

A premix of feed and oxazepam was prepared, then layered with the remaining feed and blended in a Patterson-Kelly twin-shell blender with 

the intensifier bar on for 5 minutes and off for 10 minutes. Doses were prepared every 2 weeks. 

Chemical Lot Number 

Maximum Storage Time 

3 weeks 

Storage Conditions 

Stored in polyethylene bags inside polypropylene buckets, protected from light, at 5E C 

Study Laboratory 

Battelle Columbus Laboratories 

(Columbus, OH) 
Oxazepam, NTP TR 468 161 

TABLE D2 

Analysis of Dose Formulations Administered to Rats in the 2-Year Feed Study of Oxazepam 

Target Determined Difference a Date Prepared Date Analyzed Concentration Concentration from Target 

(ppm) (ppm) (%) 

13 September 1991 19 September 1991 625 613 !2 

1,250 1,250 0 

2,500 2,550 +2 

5,000 4,980 0 

10,000 9,810 !2 

2 October 1991b 625 607 !3 

1,250 1,260 +1 

2,500 2,500 0 

5,000 4,700 !6 

10,000 10,100 +1 

8 November 1991 11 November 1991 625 612 !2 

1,250 1,240 !1 

2,500 2,490 0 

5,000 4,940 !1 

10,000 9,900 !1 

3 January 1992 7 January 1992 625 658 +5 

1,250 1,280 +2 

2,500 2,590 +4 

5,000 5,000 0 

10,000 10,100 +1 

28 February 1992 28 February 1992 625 644 +3 

1,250 1,290 +3 

2,500 2,590 +4 

5,000 5,040 +1 

10,000 9,870 !1 

19 March 1992b 625 697 +12 

1,250 1,330 +6 

2,500 2,650 +6 

5,000 5,340 +7 

10,000 10,400 +4 

24 April 1992 27 April 1992 625 627 0 

2,500 2,550 +2 

5,000 5,000 0 

19 June 1992 23 June 1992 625 599 !4 

2,500 2,530 +1 

5,000 4,700 !6 

14 August 1992 14-15 August 1992 625 604 !3 

2,500 2,500 0 

5,000 4,830 !3 

8-9 September 1992b 625 581 !7 

2,500 2,220 !11 

5,000 5,040 +1 

9 October 1992 9-10 October 1992 625 603 !4 

2,500 2,440 !2 

5,000 4,860 !3 
162 Oxazepam, NTP TR 468 

TABLE D2
 

Analysis of Dose Formulations Administered to Rats in the 2-Year Feed Study of Oxazepam (continued)
 

Target Determined Difference 

Date Prepared Date Analyzed Concentration Concentration from Target 

(ppm) (ppm) (%) 

4 December 1992 5-8 December 1992 625 

2,500 

5,000 

625 

2,750 

4,870 

0 

+10 

!3 

29 January 1993 29-30 January 1993 625 

2,500 

5,000 

650 

2,630 

5,300 

+4 

+5 

+6 

19 February 1993b 625 

2,500 

5,000 

611 

2,550 

5,080 

!2 

+2 

+2 

26 March 1993 26-27 March 1993 625 

2,500 

5,000 

617 

2,490 

5,280 

!1 

0 

+6 

21 May 1993 24-25 May 1993 625 

2,500 

5,000 

654 

2,650 

5,360 

+5 

+6 

+7 

16 July 1993 16 July 1993 625 

2,500 

5,000 

571 

2,530 

4,970 

!9 

+1 

!1 

6 August 1993b 625 

2,500 

5,000 

642 

2,570 

5,030 

+3 

+3 

+1 

13 September 1993 14 September 1993 625 

2,500 

5,000 

605 

2,500 

4,810 

!3 

0 

!4 

a 

b Results of duplicate analyses 

Animal room samples 
163 

APPENDIX E 

FEED AND COMPOUND CONSUMPTION 

IN THE 2-YEAR FEED STUDIES 

OF OXAZEPAM 

TABLE E1 

TABLE E2 

Feed and Compound Consumption by Male Rats in the 2-Year Feed Study 

of Oxazepam .................................................... 

Feed and Compound Consumption by Female Rats in the 2-Year Feed Study 

of Oxazepam .................................................... 

164 

166 
164 Oxazepam, NTP TR 468 

TABLE E1 

Feed and Compound Consumption by Male Rats in the 2-Year Feed Study of Oxazepam 

0 ppm 625 ppm 2,500 ppm 

Feed 

(g/day)a Body 

Weight 

Feed 

(g/day) 

Body 

Weight 

Dose/ 

Dayb 

Feed 

(g/day) 

Body 

Weight 

Dose/ 

Day 

Week (g) (g) (mg/kg) (g) (mg/kg) 

1 15.1 132 13.7 132 65 11.9 132 226 

2 15.6 172 16.5 179 57 16.0 174 230 

4 18.3 240 18.7 246 48 19.0 242 196 

5 16.8 257 18.0 265 43 17.7 262 169 

8 15.7 310 16.5 315 33 16.3 306 133 

9 17.4 323 17.9 326 34 17.2 314 137 

12 16.6 356 17.8 354 31 17.4 343 127 

13 17.8 367 19.2 366 33 18.5 349 132 

17 17.0 402 17.3 391 28 17.1 375 114 

21 17.0 422 17.4 413 26 16.1 393 102 

25 16.8 442 17.3 434 25 17.5 408 107 

29 17.3 462 16.5 448 23 15.9 426 93 

33 16.3 477 16.1 459 22 16.4 437 94 

37 15.9 479 16.4 465 22 15.6 438 89 

41 17.0 487 16.2 471 22 16.5 443 93 

45 16.7 492 15.9 479 21 16.7 451 92 

49 16.4 497 16.4 485 21 15.3 454 84 

53 17.0 503 16.3 492 21 16.4 449 91 

57 16.0 509 15.9 496 20 15.1 451 84 

61 14.8 509 15.0 488 19 14.0 449 78 

65 15.9 504 15.2 486 19 14.9 445 84 

69 15.9 506 16.1 492 21 15.7 443 88 

73 15.2 508 15.0 487 19 14.4 434 83 

77 16.4 500 16.3 478 21 15.4 432 89 

78 14.9 500 14.2 476 19 14.5 431 84 

81 15.4 493 13.7 471 18 13.4 414 81 

85 15.2 495 14.9 463 20 14.9 407 92 

88 14.6 493 14.5 452 20 13.2 396 83 

93 14.7 489 15.0 449 21 14.8 397 93 

97 14.0 470 16.0 441 23 15.4 372 104 

101 11.7 459 14.5 429 21 15.7 349 112 

104 14.8 463 16.7 428 24 15.1 341 111 

Mean for weeks 

1-13 16.7 270 17.3 273 43 16.7 265 169 

14-52 16.7 462 16.6 449 23 16.3 425 97 

53-104 15.1 493 15.3 468 20 14.9 414 90 
Oxazepam, NTP TR 468 165 

TABLE E1
 

Feed and Compound Consumption by Male Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 5,000 ppm 10,000 ppm 

Feed Body Feed Body Dose/ Feed Body Dose/ 

(g/day) Weight (g/day) Weight Day (g/day) Weight Day 

Week (g) (g) (mg/kg) (g) (mg/kg) 

1 15.1 132 10.8 132 409 10.4 132 791 

2 15.6 172 15.3 168 456 14.8 164 901 

4 18.3 240 19.1 238 400 19.3 232 833 

5 16.8 257 17.5 254 346 17.5 247 711 

8 15.7 310 17.3 294 294 16.1 284 568 

9 17.4 323 18.6 304 307 17.1 290 591 

12 16.6 356 16.7 331 253 16.9 322 524 

13 17.8 367 18.8 338 277 18.1 323 561 

17 17.0 402 16.5 355 233 17.4 344 506 

21 17.0 422 18.0 375 240 17.3 358 485 

25 16.8 442 16.3 386 212 16.7 366 457 

29 17.3 462 16.5 400 207 16.0 361 

33 16.3 477 15.5 401 193 17.9 404 

37 15.9 479 15.6 401 194 17.3 424 

41 17.0 487 16.2 411 197 17.4 437 

45 16.7 492 17.7 420 211 16.6 449 

49 16.4 497 16.6 421 197 17.0 462 

53 17.0 503 16.6 420 198 17.3 467 

57 16.0 509 16.0 417 191 16.2 472 

61 14.8 509 15.1 403 187 15.6 473 

65 15.9 504 15.6 396 197 16.0 469 

69 15.9 506 16.2 388 209 15.6 469 

73 15.2 508 16.4 363 226 15.3 474 

77 16.4 500 14.9 358 207 16.2 469 

78 14.9 500 15.2 351 216 15.6 469 

81 15.4 493 14.3 334 214 14.7 458 

85 15.2 495 15.8 328 241 14.7 445 

88 14.6 493 14.3 313 229 12.6 425 

93 14.7 489 14.6 314 233 12.9 427 

97 14.0 470 16.8 333 252 14.5 403 

101 11.7 459 7.6 285 133 

104 14.8 463 

Mean for weeks 

1-13 16.7 270 16.8 258 343 16.3 249 685 

14-52 16.7 462 16.5 397 209 17.1 401 482c 

53-104 15.1 493 15.0 357 210 15.2 455 

a 

b 

c 

Grams of feed consumed per animal per day 

Milligrams of oxazepam consumed per kilogram body weight per day 

Mean for weeks 14-27 
166 Oxazepam, NTP TR 468 

TABLE E2 

Feed and Compound Consumption by Female Rats in the 2-Year Feed Study of Oxazepam 

0 ppm 625 ppm 2,500 ppm 

Feed 

(g/day)a Body 

Weight 

Feed 

(g/day) 

Body 

Weight 

Dose/ 

Dayb 

Feed 

(g/day) 

Body 

Weight 

Dose/ 

Day 

Week (g) (g) (mg/kg) (g) (mg/kg) 

1 11.0 111 10.6 111 59 9.6 111 216 

2 11.1 129 11.7 132 55 11.3 133 212 

4 12.2 153 12.7 159 50 12.3 157 196 

5 11.5 162 11.5 167 43 12.0 165 183 

8 11.2 182 10.8 185 37 10.4 180 144 

9 10.9 187 11.2 188 37 10.9 182 149 

12 11.0 200 11.0 200 34 10.7 194 138 

13 10.6 203 11.6 206 35 11.0 197 140 

17 11.3 216 11.6 218 33 10.9 207 131 

21 10.6 223 10.8 226 30 10.1 216 117 

25 10.9 234 10.3 235 27 10.6 224 119 

29 10.9 241 11.8 245 30 10.8 232 116 

33 10.6 247 10.6 253 26 9.7 238 102 

37 10.9 255 10.1 258 25 9.8 243 101 

41 11.3 263 11.2 270 26 10.3 249 103 

45 12.4 273 10.9 280 24 10.8 259 104 

49 12.3 286 11.5 289 25 10.1 264 96 

53 11.0 298 11.4 301 24 10.0 272 92 

57 11.8 308 11.6 311 23 10.7 277 96 

61 11.4 315 11.1 318 22 10.2 284 89 

65 11.3 322 11.3 323 22 11.1 296 94 

69 12.1 328 11.9 328 23 12.1 303 100 

73 11.4 328 11.3 330 21 10.5 302 87 

77 11.8 328 11.8 333 22 11.0 304 90 

81 11.8 333 12.0 341 22 11.8 308 96 

85 12.2 339 11.7 339 21 11.6 316 92 

88 12.3 343 11.5 343 21 11.4 316 90 

93 11.6 343 11.3 344 20 11.4 317 90 

97 11.7 343 11.5 348 21 11.0 314 88 

101 12.1 348 11.1 345 20 10.1 314 81 

104 11.1 348 11.2 343 20 9.5 296 80 

Mean for weeks 

1-13 11.2 166 11.4 169 44 11.0 165 172 

14-52 11.2 249 11.0 253 27 10.3 237 110 

53-104 11.7 330 11.5 332 22 10.9 301 90 
167 

c 

Oxazepam, NTP TR 468 

TABLE E2
 

Feed and Compound Consumption by Female Rats in the 2-Year Feed Study of Oxazepam (continued)
 

0 ppm 5,000 ppm 10,000 ppm 

Feed Body Feed Body Dose/ Feed Body Dose/ 

(g/day) Weight (g/day) Weight Day (g/day) Weight Day 

Week (g) (g) (mg/kg) (g) (mg/kg) 

1 11.0 111 8.9 111 400 8.1 111 730 

2 11.1 129 11.9 134 444 11.8 133 886 

4 12.2 153 11.9 158 376 12.4 156 793 

5 11.5 162 11.0 164 333 11.4 162 707 

8 11.2 182 10.6 177 300 11.1 175 636 

9 10.9 187 11.1 182 306 10.9 177 612 

12 11.0 200 10.7 191 281 10.8 187 578 

13 10.6 203 10.7 192 279 10.8 188 576 

17 11.3 216 10.6 203 262 10.8 197 548 

21 10.6 223 10.1 208 242 10.2 202 504 

25 10.9 234 10.0 216 232 9.5 208 459 

29 10.9 241 10.3 225 229 10.5 198 

33 10.6 247 9.3 229 203 12.7 224 

37 10.9 255 9.6 235 204 10.8 235 

41 11.3 263 9.7 241 202 11.3 245 

45 12.4 273 11.1 251 221 12.0 255 

49 12.3 286 9.8 251 195 11.4 266 

53 11.0 298 9.4 256 184 11.5 277 

57 11.8 308 10.1 261 193 12.3 290 

61 11.4 315 9.6 265 181 12.0 304 

65 11.3 322 10.1 270 187 12.1 316 

69 12.1 328 11.1 278 199 12.2 323 

73 11.4 328 9.9 277 178 11.4 324 

77 11.8 328 11.8 285 207 11.9 330 

81 11.8 333 10.4 283 184 11.2 331 

85 12.2 339 10.7 288 186 11.7 336 

88 12.3 343 10.5 287 183 12.6 346 

93 11.6 343 10.5 282 186 11.5 352 

97 11.7 343 10.9 282 193 12.0 357 

101 12.1 348 10.5 285 183 10.3 356
 

104 11.1 348 11.1 284 196 10.1 346
 

Mean for weeks 

1-13 11.2 166 10.9 164 340 10.9 161 690 

14-52 11.2 249 10.1 229 221 11.0 225 504c 

53-104 11.7 330 10.5 277 189 11.6 328 

a Grams of feed consumed per animal per day b	 Milligrams of oxazepam consumed per kilogram body weight per day 

Mean for weeks 14-27 
168 Oxazepam, NTP TR 468
 
169 

APPENDIX F 

INGREDIENTS, NUTRIENT COMPOSITION, 

AND CONTAMINANT LEVELS 

IN NIH-07 RAT AND MOUSE RATION 

TABLE F1 

TABLE F2 

TABLE F3 

TABLE F4 

Ingredients of NIH-07 Rat and Mouse Ration ............................. 

Vitamins and Minerals in NIH-07 Rat and Mouse Ration ..................... 

Nutrient Composition of NIH-07 Rat and Mouse Ration ..................... 

Contaminant Levels in NIH-07 Rat and Mouse Ration ....................... 

170 

170 

171 

172 
170 Oxazepam, NTP TR 468 

TABLE F1 

Ingredients of NIH-07 Rat and Mouse Rationa 

Ingredientsb Percent by Weight 

Ground #2 yellow shelled corn 24.50 

Ground hard winter wheat 23.00 

Soybean meal (49% protein) 12.00 

Fish meal (60% protein) 10.00 

Wheat middlings 10.00 

Dried skim milk 5.00 

Alfalfa meal (dehydrated, 17% protein) 4.00 

Corn gluten meal (60% protein) 3.00 

Soy oil 2.50 

Dried brewer’s yeast 2.00 

Dry molasses 1.50 

Dicalcium phosphate 1.25 

Ground limestone 0.50 

Salt 0.50 

Premixes (vitamin and mineral) 0.25 

a NCI, 1976; NIH, 1978 b Ingredients were ground to pass through a U.S. Standard Screen No. 16 before being mixed. 

TABLE F2 

Vitamins and Minerals in NIH-07 Rat and Mouse Rationa 

Amount Source 

Vitamins 

A 5,500,000 IU Stabilized vitamin A palmitate or acetate 

D3 4,600,000 IU D-activated animal sterol 

K3 

"-Tocopheryl acetate 

2.8 g 

20,000 IU 

Menadione 

Choline 560.0 g Choline chloride 

Folic acid 2.2 g 

Niacin 30.0 g 

d-Pantothenic acid 18.0 g d-Calcium pantothenate 

Riboflavin 3.4 g 

Thiamine 10.0 g Thiamine mononitrate 

B12 4,000 μg 

Pyridoxine 1.7 g Pyridoxine hydrochloride 

Biotin 140.0 mg d-Biotin 

Minerals 

Iron 120.0 g Iron sulfate 

Manganese 60.0 g Manganous oxide 

Zinc 16.0 g Zinc oxide 

Copper 4.0 g Copper sulfate 

Iodine 1.4 g Calcium iodate 

Cobalt 0.4 g Cobalt carbonate 

a Per ton (2,000 lb) of finished product 
Oxazepam, NTP TR 468 171 

TABLE F3 

Nutrient Composition of NIH-07 Rat and Mouse Ration 

Mean ± Standard 

Nutrient Deviation Range Number of Samples 

Protein (% by weight) 23.43 ± 0.51 22.3 ) 24.2 23 

Crude fat (% by weight) 5.38 ± 0.19 5.10 ) 5.70 23 

Crude fiber (% by weight) 3.25 ± 0.22 2.90 ) 3.80 23 

Ash (% by weight) 6.53 ± 0.25 6.08 ) 7.03 23 

Amino Acids (% of total diet) 

Arginine 1.280 ± 0.083 1.110 ) 1.390 11 

Cystine 0.308 ± 0.071 0.181 ) 0.400 11 

Glycine 1.158 ± 0.048 1.060 ) 1.220 11 

Histidine 0.584 ± 0.027 0.531 ) 0.630 11 

Isoleucine 0.917 ± 0.033 0.867 ) 0.965 11 

Leucine 1.975 ± 0.051 1.850 ) 2.040 11 

Lysine 1.274 ± 0.049 1.200 ) 1.370 11 

Methionine 0.437 ± 0.109 0.306 ) 0.699 11 

Phenylalanine 0.999 ± 0.120 0.665 ) 1.110 11 

Threonine 0.904 ± 0.058 0.824 ) 0.985 11 

Tryptophan 0.218 ± 0.153 0.107 ) 0.671 11 

Tyrosine 0.685 ± 0.094 0.564 ) 0.794 11 

Valine 1.086 ± 0.055 0.962 ) 1.170 11 

Essential Fatty Acids (% of total diet) 

Linoleic 2.407 ± 0.227 1.830 ) 2.570 10 

Linolenic 0.259 ± 0.065 0.100 ) 0.320 10 

Vitamins 

Vitamin A (IU/kg) 6,667 ± 553 5,940 ) 8,580 23 

Vitamin D (IU/kg) 4,450 ± 1,382 3,000 ) 6,300 4 

"-Tocopherol (ppm) 35.43 ± 8.98 22.5 ) 48.9 11 

Thiamine (ppm) 17.35 ± 3.14 12.0 ) 25.0 23 

Riboflavin (ppm) 7.83 ± 0.923 6.10 ) 9.00 11 

Niacin (ppm) 99.22 ± 24.27 65.0 ) 150.0 11 

Pantothenic acid (ppm) 30.55 ± 3.52 23.0 ) 34.6 11 

Pyridoxine (ppm) 9.11 ± 2.53 5.60 ) 14.0 11 

Folic acid (ppm) 2.46 ± 0.63 1.80 ) 3.70 11 

Biotin (ppm) 0.268 ± 0.047 0.190 ) 0.354 11 

Vitamin B (ppb) 40.5 ± 19.1 10.6 ) 65.0 11 12 

Choline (ppm) 2,991 ± 382 2,300 ) 3,430 10 

Minerals 

Calcium (%) 1.17 ± 0.09 1.02 ) 1.32 23 

Phosphorus (%) 0.92 ± 0.06 0.770 ) 1.00 23 

Potassium (%) 0.886 ± 0.063 0.772 ) 0.971 9 

Chloride (%) 0.529 ± 0.087 0.380 ) 0.635 9 

Sodium (%) 0.316 ± 0.033 0.258 ) 0.371 11 

Magnesium (%) 0.166 ± 0.010 0.148 ) 0.181 11 

Sulfur (%) 0.272 ± 0.059 0.208 ) 0.420 10 

Iron (ppm) 350.5 ± 87.3 255.0 ) 523.0 11 

Manganese (ppm) 92.48 ± 5.14 81.7 ) 99.4 11 

Zinc (ppm) 59.33 ± 10.2 46.1 ) 81.6 11 

Copper (ppm) 11.81 ± 2.50 8.09 ) 15.4 11 

Iodine (ppm) 3.54 ± 1.19 1.52 ) 5.83 10 

Chromium (ppm) 1.66 ± 0.46 0.85 ) 2.09 11 

Cobalt (ppm) 0.76 ± 0.23 0.49 ) 1.15 7 
172 Oxazepam, NTP TR 468 

TABLE F4 

Contaminant Levels in NIH-07 Rat and Mouse Rationa 

Mean ± Standard 

Deviationb Range Number of Samples 

Contaminants 

Arsenic (ppm) 0.57 ± 0.13 0.03 ) 0.80 23 

Cadmium (ppm) 0.12 ± 0.08 0.04 ) 0.20 23 

Lead (ppm) 0.30 ± 0.13 0.18 ) 0.70 23 c Mercury (ppm) 0.02 0.02 ) 0.03 23 

Selenium (ppm) 0.36 ± 0.08 0.10 ) 0.40 23 

Aflatoxins (ppm) <5.0 23 

Nitrate nitrogen (ppm)d 6.43 ± 2.62 1.80 ) 11.0 23 

Nitrite nitrogen (ppm)d 0.45 ± 0.64 0.02 ) 2.90 23 e BHA (ppm) 1.43 ± 1.88 1.00 ) 10.0 23 e BHT (ppm) 1.30 ± 0.88 1.0 ) 5.00 23 

Aerobic plate count (CFU/g) 135,565 ± 173,947 10,000 ) 630,000 23 

Coliform (MPN/g) 100 ± 244 3 ) 1,100 23 

Escherichia coli (MPN/g) <3.0 23 

Salmonella (MPN/g) Negative 23 

Total nitrosoamines (ppb)f 9.66 ± 4.73 4.80 ) 19.70 23 

N-Nitrosodimethylamine (ppb)f 7.48 ± 4.38 3.40 ) 18.00 23 

N-Nitrosopyrrolidine (ppb)f 2.21 ± 1.13 1.00 ) 5.80 23 

Pesticides (ppm) 

"-BHC <0.01 23 

$-BHC <0.02 23 

(-BHC <0.01 23 

*-BHC <0.01 23 

Heptachlor <0.01 23 

Aldrin <0.01 23 

Heptachlor epoxide <0.01 23 

DDE <0.01 23 

DDD <0.01 23 

DDT <0.01 23 

HCB <0.01 23 

Mirex <0.01 23 

Methoxychlor <0.05 23 

Dieldrin <0.01 23 

Endrin <0.01 23 

Telodrin <0.01 23 

Chlordane <0.05 23 

Toxaphene <0.10 23 

Estimated PCBs <0.20 23 

Ronnel <0.01 23 

Ethion <0.02 23 

Trithion <0.05 23 

Diazinon <0.10 23 

Methyl parathion <0.02 23 

Ethyl parathion <0.02 23 

Malathion 0.14 ± 0.16 0.05 ) 0.48 23 

Endosulfan I <0.01 23 

Endosulfan II <0.01 23 

Endosulfan sulfate <0.03 23 

a CFU=colony forming units; MPN=most probable number; BHC=hexachlorocyclohexane or benzene hexachloride b For values less than the limit of detection, the detection limit is given as the mean. 

All but three values were less than detection limit; detection limit is used for the low end of the range. d Sources of contamination: alfalfa, grains, and fish meal e Sources of contamination: soy oil and fish meal f All values were corrected for percent recovery. 

c 
173 

APPENDIX G 

SENTINEL ANIMAL PROGRAM 

METHODS 

RESULTS 

............................................................... 

............................................................... 

174 

174 
 

174 Oxazepam, NTP TR 468 

SENTINEL ANIMAL PROGRAM
 

METHODS 

Rodents used in the Carcinogenesis Program of the National Toxicology Program are produced in optimally 

clean facilities to eliminate potential pathogens that may affect study results. The Sentinel Animal Program is 

part of the periodic monitoring of animal health that occurs during the toxicologic evaluation of chemical 

compounds. Under this program, the disease state of rodents is monitored via serology on sera from extra 

(sentinel) animals in the study rooms. These animals and the study animals are all subject to identical 

environmental conditions. The sentinel animals come from the same production source and weanling groups 

as the animals used for the studies of chemical compounds. 

Serum samples were collected from randomly selected rats during the 2-year study. Blood from each animal 

was collected and allowed to clot, and the serum was separated. The samples were processed appropriately 

and sent to Microbiological Associates Inc. (Bethesda, MD), for determination of antibody titers. The 

laboratory serology methods and viral agents for which testing was performed are tabulated below; the times 

at which the blood was collected during the studies are also listed. 

Method and Test Time of Analysis 

2-Year Study 

ELISA

 Mycoplasma arthritidis 

Mycoplasma pulmonis 

PVM (pneumonia virus of mice) 

RCV/SDA (rat coronavirus/sialodacryoadenitis virus) 

Sendai 

Study termination 

Study termination

6, 12, and 18 months, study termination

6, 12, and 18 months, study termination

6, 12, and 18 months, study termination 

Hemagglutination Inhibition

 H-1 (Toolan’s H-1 virus) 

KRV (Kilham rat virus) 

6, 12, and 18 months, study termination

6, 12, and 18 months, study termination 

RESULTS 

Two rats had positive titers to M. arthritidis at study termination. Further evaluations of the serum positive 

for M. arthritidis by immunoblot and Western blot procedures indicated that the positive titers may have 

been due to cross reaction with antibodies of nonpathogenic Mycoplasma or other agents. Only sporadic 

samples were positive, and there were no clinical findings or histopathologic changes of M. arthritidis 

infection in animals with positive titers. Accordingly, the M. arthritidis-positive titers were considered false 

positives. 
175 

APPENDIX H
 

EARLY RESPONSES OF F344/N RATS
 

TO OXAZEPAM
 

Michael L. Cunningham and John R. Bucher
 

Environmental Toxicology Program
 

National Institute of Environmental Health Sciences
 

Research Triangle Park, North Carolina
 

INTRODUCTION ............................................................ 176
 

MATERIALS AND METHODS .................................................... 176
 

RESULTS ................................................................ 178
 

REFERENCES .............................................................. 180
 

TABLE H1 Survival, Body Weights, and Feed Consumption of Male F344/N Rats
 

Administered Oxazepam in Feed for 90 Days .............................. 181
 

TABLE H2 BrdU and Proliferating Cell Nuclear Antigen Labeling Indices,
 

Liver Weight/Body Weight Ratios, and Total Body Burden of Male F344/N Rats 

Administered Oxazepam in Feed for 90 Days .............................. 182
 

TABLE H3 Clinical Chemistry Data for Male F344/N Rats Administered Oxazepam
 

in Feed for 90 Days ............................................... 183
 

TABLE H4 Serum Oxazepam Concentrations in Male F344/N Rats Administered Oxazepam
 

in Feed for 90 Days ............................................... 184
 
176 Oxazepam, NTP TR 468 

EARLY RESPONSES OF F344/N RATS TO OXAZEPAM
 

INTRODUCTION 

Oxazepam and related benzodiazepine drugs are used in the treatment of anxiety. Most clinically useful 

drugs for this purpose are variants of the 1,4-benzodiazepine structure comprising two aromatic rings and a 

seven-membered heterocycle. One of the aromatic rings is fused to the seven-membered ring and contains a 

chloro-substituent or some other electronegative group. All clinically important derivatives contain a 5-aryl 

or 5-cyclohexenyl group. Most of the drugs vary in substituent groups at the 1 and 3 positions (Goodman 

and Gilman’s, 1990). Oxazepam, known under the trade name Serax®, is produced and sold by Wyeth 

Laboratories and has been on the market since 1965. 

Two million six hundred thousand prescriptions for oxazepam were written in the United States in 1983, and 

oxazepam ranked 132nd and 125th in overall frequency of prescriptions written for all drugs in 1984 and 

1985, respectively (Anonymous, 1986; C. Baum correspondence, 1986). Oxazepam is also a common 

metabolite of several other benzodiazepines, some of which are more widely prescribed. These include 

diazepam (Valium®), for which 25.5 million prescriptions were written in 1983, making it the fourth most 

prescribed drug. The use of benzodiazepines in the general population in the United States has been reported 

to be as high as 7% (Pedersen and Lavik, 1991). 

In NTP studies, oxazepam was not mutagenic in any of several strains of Salmonella typhimurium, nor did it 

induce sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells with 

or without metabolic activation. However, Fox and Lahcen (1974) observed liver neoplasms in oxazepamtreated Swiss-Webster mice during the course of reproductive toxicity studies, and oxazepam caused 

increased incidences of liver neoplasms in male and female Swiss-Webster and B6C3F1 mice in 2-year NTP

feed studies (NTP, 1993). A 2-year feed study was subsequently started using F344/N rats. Because of the 

resemblance of the mouse results to those with other apparently nonnecrogenic and nongenotoxic liver 

carcinogens and the earlier observation that oxazepam was hepatocarcinogenic in both Swiss-Webster and 

B6C3F1 mice, oxazepam was concurrently evaluated for clinical pathology and hepatocellular cell replication

in a 13-week feed study with male F344/N rats. Exposure concentrations administered via feed were 

identical to those in the B6C3F1 mouse study (Cunningham et al., 1994a). Serum oxazepam levels were also

evaluated for comparison to the previous mouse studies and to therapeutic human levels. 

MATERIALS AND METHODS 

Animals 

Male Fisher 344/N rats (Charles River Breeding Laboratories, Raleigh, NC) weighing 150 g were fed a 

standard NIH 31 diet ad libitum and exposed to a daily cycle of alternating 12-hour periods of light and 

dark. The rats were acclimated to this environment for 2 weeks prior to the beginning of the study; animal 

rooms were maintained at 21E to 23E C and 40% to 60% relative humidity throughout the study. Rats were 

randomly assigned to exposure groups of 10 animals per group and allowed 7 days to adapt to a new cage 

environment and the powdered chow mixture (without oxazepam) described below. Experiments were 

performed according to the guidelines established in the NIH Guide for the Care and Use of Laboratory 

Animals. Animals were killed by CO asphyxiation and exsanguination. Blood samples were allowed to clot 2 

for approximately 30 minutes at room temperature, after which they were centrifuged at 5,000 × g for 

5 minutes. Serum was collected and immediately analyzed for activities or concentrations of the following: 

albumin, total protein, alkaline phosphatase, alanine aminotransferase, creatine kinase, sorbitol 

dehydrogenase, 5N-nucleotidase, total bile acids, creatinine, and total cholesterol. All analyses were 

performed using a Monarch 2000 chemistry analyzer (Instrumentation Laboratories, Lexington, MA). 

Except for total bile acids and 5N-nucleotidase, all assays were performed using reagent kits and standard 

applications developed for the analyzer by the manufacturer. Assays for total bile acids and 5N-nucleotidase 
Oxazepam, NTP TR 468 177 

were developed for the analyzer using reagent kits obtained from Sigma Chemical Company (St. Louis, 

MO). Experimental effects for clinical chemistry measurements were identified by analysis of variance. 

Significant differences between animals in exposed and control groups were detected using Dunnett’s 

multiple comparison test (Dunnett, 1955). 

Chemical Exposure 

Oxazepam was acquired from the National Toxicology Program repository from the lots used for the 2-year 

carcinogenicity studies. Dosed feed was prepared biweekly in 7-kg batches by Radian Corporation 

(Research Triangle Park, NC) by mixing ground feed and oxazepam in a Patterson-Kelly blender for 

15 minutes with the intensifier bar in operation for the first 5 minutes. Aliquots were analyzed by highperformance liquid chromatography (HPLC) using acetophenone as the internal standard (details available 

upon request). Concentrations of oxazepam in feed were within 10% of target concentrations. Control 

animals received an identical powdered chow mixture with no oxazepam. Powdered chow was delivered to 

rats in stainless steel hanging feeders covered with wire mesh to prevent feed scattering. Estimations of feed 

consumption were performed weekly. 

Cell Proliferation Measurements 

Seven days before the end of the study, osmotic minipumps (Model 2002, Alza Corporation, Palo Alto, CA) 

were implanted subcutaneously into the backs of the rats. These minipumps delivered 30 mg 

bromodeoxyuridine (BrdU) (Sigma Chemical Co.) per hour, which was incorporated into the DNA of newly 

replicating cells. At the end of the study, animals were killed by CO inhalation, and blood was collected for 2 

clinical chemistry measurements and analysis of oxazepam levels. Livers and kidneys were blotted and 

weighed. A mid-lobe radial section of the right anterior lobe was fixed in neutral buffered formalin for 

24 hours. A cross section of small intestine was also fixed as a positive control for the proper operation of 

the minipump and the staining technique because these cells are constantly in S phase. Tissues were 

embedded in paraffin, and serial sections were mounted onto slides coated with poly-l-lysine. Following 

deparaffination and rehydration, one set of slides was stained with hematoxylin and eosin for histological 

analysis, and another set was stained immunohistochemically for BrdU incorporation as described previously 

(Cunningham and Matthews, 1991; Cunningham et al., 1991, 1994a, 1994b). Slides were treated with 2 N 

HCl for 30 minutes at 37 EC to allow the DNA to become single stranded. The acid treatment was quenched 

with boric acid buffer (pH 7.6) for 1 minute at room temperature, followed by digestion in 0.01% trypsin 

(Sigma Chemical Co.) and rinsed in PBT [phosphate buffer, pH 7.2, containing 1% bovine serum albumin 

(Sigma Chemical Co.), 0.05% Tween 20 (Bio-Rad, Richmond, CA) and 7.2% NaCl]. Nonspecific antibody 

binding was eliminated by blocking (20 minutes) with normal horse serum (1:20) (Vector Laboratories, Inc., 

Burlington, CA). Following a PBT wash, the slides were incubated with a 1:50 dilution of mouse 

monoclonal antibody to BrdU (Becton Dickenson, Mountain View, CA) for 20 minutes at room temperature. 

Following two PBT washes, the slides were incubated with a 1:100 dilution of a biotinylated horse antimouse antibody (Vector Laboratories, Inc.; rat absorbed) for 20 minutes at room temperature and visualized 

with the avidin biotin peroxidase complex (ABC) method using a Vectastain peroxidase standard kit (Vector 

Laboratories, Inc.). Nuclei binding the ABC reagent (labeled nuclei) were stained for 6 minutes with 3,3Ndiaminobenzidine (Sigma Chemical Co.) to give a dark brown color, and nonlabeled nuclei were stained with 

hematoxylin to yield a blue color. Random areas of the slides were chosen for counting stained and 

unstained hepatocyte nuclei (>1,000 hepatocytes/rat). Statistics were performed using Student’s t-test. 

Serum Oxazepam Analysis 

Frozen serum was allowed to thaw, and 0.1 mL aliquots were made basic with 10 μL 0.1 M NaOH. Parent 

oxazepam was extracted from the aqueous layer with 1 mL ethyl acetate followed by centrifugation 

(1,500 rpm for 5 minutes). The organic layer containing the oxazepam was removed and evaporated to 

dryness under nitrogen. Samples were reconstituted in 100 μL 0.05 M 60% methanol:40% phosphate 

buffer; pH 2.8). Samples were analyzed for oxazepam by HPLC (Waters Associates, Milford, MA); the 

system consisted of two Model 510 HPLC pumps, a 712 WISP multiple sample injector, a 
178 Oxazepam, NTP TR 468 

490E multiwavelength detector at 230 nm, and a C18 column. Samples were run isocratically at 

0.8 mL/minute in a methanol:phosphate buffer (60:40) carrier. Serum oxazepam was quantitated against an 

oxazepam standard curve created with spiked serum standards. 

RESULTS 

All rats survived to the end of the study, although oxazepam had a sedative effect on the rats in the 

5,000 ppm groups. Rats in the 2,500 and 5,000 ppm groups consumed significantly less feed than did 

controls at the 15-, 30-, and 45-day intervals (Table H1). Other sporadic differences in feed consumption 

were also noted. Animals in the 2,500 and 5,000 ppm groups were observed to be sluggish for the first 2 to 

4 weeks, but activity levels appeared normal thereafter. On day 15, the final mean body weights and body 

weight gains of the 2,500 and 5,000 ppm groups were significantly less than those of the control group, but 

were similar on day 30. The mean body weight gains of the 5,000 ppm group were less than those of the 

control group on days 45 and 90 as was that of 2,500 ppm rats on day 90 (Table H1). 

The amount of hepatocellular proliferation was examined in relation to the amount of oxazepam consumed 

and the relative increase in liver weight over the course of this study. Male rats exposed to 2,500 or 

5,000 ppm oxazepam exhibited a significant increase in the rate of hepatocyte cell proliferation as determined 

by BrdU incorporation as well as by PCNA staining at the 15-day time point (Table H2). By day 15, BrdU 

labeling indices in these groups were approximately three- to five-fold the untreated control indices, 

respectively. Both labeling indices in these groups were also significantly elevated compared to those of the 

controls on day 30, but this increase more likely reflects the variably lowered control labeling observed for 

both BrdU labeling and PCNA labeling. Labeling indices of all exposed groups were similar to those of the 

controls for both BrdU and PCNA at the 45- and 90-day time points. 

Liver weight/body weight ratios in the 2,500 and 5,000 ppm groups were significantly greater than the 

control value at all time points (Table H2). Liver weight/body weight ratios in the 25 and 125 ppm groups 

were slightly elevated only at the 45-day time point. Rats exposed to 5,000 ppm oxazepam received 

approximately 19,000 mg oxazepam/kg body weight over 90 days. 

Slight variations in serum activities of alanine aminotransferase, alkaline phosphatase, and 5N-nucleotidase 

were observed in the serum of rats exposed to 2,500 or 5,000 ppm oxazepam at various time points 

(Table H3). Other mild but statistically significant changes included decreases in cholesterol concentrations 

in the 2,500 and 5,000 ppm groups on days 30 and 90 and in the 5,000 ppm group on day 45, and an 

increase in bile acid concentration in the 5,000 ppm group on day 30. Increases in albumin concentrations 

occurred in 5,000 ppm rats on days 30 and 45 and in 2,500 and 5,000 ppm rats on day 90. Mild, 

statistically significant decreases in activities of sorbitol dehydrogenase and creatinine occurred in exposed 

groups. None of these changes was considered to have biological importance. 

Histopathologic evaluation of hematoxylin- and eosin-stained slides revealed little histologic evidence of 

cytotoxicity or hepatocyte degeneration and no generalized or periportal inflammation. The major 

histological feature of rats exposed to oxazepam was hypertrophy, characterized by enlarged hepatocytes 

with pale pink, nonvacuolated cytoplasm. In the 25 and 125 ppm groups, hypertrophy was centrilobular, 

was consistent with proliferation of smooth endoplasmic reticulum, and encompassed hepatocytes two to 

six cells deep emanating from the central vein. At 2,500 and 5,000 ppm, hypertrophy became more 

extensive, and the area of enlargement of hepatocytes included the periportal region. Although the largest 
Oxazepam, NTP TR 468 179 

hepatocytes were usually found around the central vein, all hepatocytes in rats exposed to 2,500 or 

5,000 ppm were markedly enlarged and pale, causing generalized occlusion of sinusoids. 

Serum oxazepam concentrations increased as a function of exposure concentration in all groups (Table H4). 

The highest serum oxazepam concentration, approximately 3.63 μg/mL, occurred in the 5,000 ppm group on 

day 90. Serum oxazepam concentrations appeared unstable between 15 and 90 days in the 2,500 and 

5,000 ppm groups, dropping after 15 days and returning to high concentrations by 90 days. This was 

apparently due to the induction of drug metabolizing (Phase I) and conjugating enzymes (Phase II), with a 

concomitant increase in total body clearance of oxazepam (Griffin and Burka, 1995). The serum oxazepam 

concentrations observed in rats are approximately 10% of those attained in mice exposed for the same 

amount of time to the same exposure concentrations in earlier studies (Cunningham et al., 1994a). 
180 Oxazepam, NTP TR 468 

REFERENCES 

Anonymous (1986). Top 200 Drugs of 1985: A 1.4% increase in refills nudges 1985 rxs 1.1% ahead of 

1984 volume. Pharm. Times 52, 25-33. 

Cunningham, M.L., and Matthews, H.B. (1991). Relationship of hepatocarcinogenicity and hepatocellular 

proliferation induced by mutagenic noncarcinogens vs carcinogens. II. 1- vs 2-nitropropane. Toxicol. Appl. 

Pharmacol. 110, 505-513. 

Cunningham, M.L., Foley, J., Maronpot, R.R., and Matthews, H.B. (1991). Correlation of hepatocellular 

proliferation with hepatocarcinogenicity induced by the mutagenic noncarcinogen:carcinogen pair — 

2,6- and 2,4-diaminotoluene. Toxicol. Appl. Pharmacol. 107, 562-567. 

Cunningham, M.L., Maronpot, R.R., Thompson, M., and Bucher, J.R. (1994a). Early responses of the 

liver of B6C3F1 mice to the hepatocarcinogen oxazepam. Toxicol. Appl. Pharmacol. 124, 31-38. 

Cunningham, M.L., Elwell, M.R., and Matthews, H.B. (1994b). Relationship of carcinogenicity and 

cellular proliferation induced by mutagenic noncarcinogens vs carcinogens. III. Organophosphate pesticides 

vs tris(2,3-dibromopropyl)phosphate. Fundam. Appl. Toxicol. 23, 363-369. 

Dunnett, C.W. (1955). A multiple comparison procedure for comparing several treatments with a control. 

J. Am. Stat. Assoc. 50, 1096-1121. 

Fox, K.A., and Lahcen, R.B. (1974). Liver-cell adenomas and peliosis hepatis in mice associated with 

oxazepam. Res. Commun. Chem. Pathol. Pharmacol. 8, 481-488. 

Goodman and Gilman’s The Pharmacological Basis of Therapeutics (1990). 8th ed. (A.G. Gilman, 

T.W. Rall, A.S. Nies, and P. Taylor, Eds.), p. 357. Pergamon Press, Inc., New York. 

Griffin, R.J., and Burka, L.T. (1995). Metabolism and elimination of oxazepam in F344 rats. Drug Metab. 

Dispos. 23, 232-239. 

National Toxicology Program (NTP) (1993). Toxicology and Carcinogenesis Studies of Oxazepam (CAS 

No. 604-75-1) in Swiss-Webster and B6C3F1 Mice (Feed Studies). Technical Report Series No. 443. NIH

Publication No. 93-3359. U.S. Department of Health and Human Services, Public Health Service, National 

Institutes of Health, Research Triangle Park, NC. 

Pedersen, W., and Lavik, N.J. (1991). Adolescents and benzodiazepines: Prescribed use, self-medication 

and intoxication. Acta Psychiatr. Scand. 84, 94-98. 
181 

c 

Oxazepam, NTP TR 468 

TABLE H1 

Survival, Body Weights, and Feed Consumption of Male F344/N Rats Administered Oxazepam 

in Feed for 90 Days 

Concentration 

(ppm) 

Survivala Initial 

Mean Body Weight (g) b 

Final Change 

Final Weight 

Relative 

to Controls 

(%) 

Feed 

Consumptionc 

15 Days 

0 

25 

125 

2,500 

5,000 

10/10 

10/10 

10/10 

10/10 

10/10 

201 ± 6 

200 ± 5 

201 ± 5 

196 ± 6 

203 ± 6 

247 ± 10 

243 ± 6 

246 ± 7 

235 ± 8** 

233 ± 12* 

46 ± 7 

43 ± 4 

45 ± 4 

38 ± 10* 

32 ± 8** 

93 

98 

83 

70 

14.1 

12.8* 

13.2 

11.7* 

9.8* 

30 Days 

0 

25 

125 

2,500 

5,000 

10/10 

10/10 

10/10 

10/10 

10/10 

198 ± 6 

200 ± 5 

200 ± 6 

197 ± 7 

192 ± 8 

278 ± 9 

287 ± 7* 

280 ± 7 

276 ± 11 

265 ± 17 

79 ± 6 

87 ± 5 

80 ± 7 

79 ± 9 

74 ± 13 

110 

101 

100 

94 

15.2 

14.3** 

13.9** 

13.4** 

12.6** 

45 Days 

0 

25 

125 

2,500 

5,000 

10/10 

10/10 

10/10 

10/10 

10/10 

199 ± 7 

202 ± 9 

198 ± 6 

195 ± 7 

198 ± 6 

299 ± 13 

310 ± 11 

307 ± 14 

292 ± 16 

286 ± 9 

100 ± 11 

108 ± 5 

110 ± 12 

98 ± 16 

87 ± 10** 

108 

110 

98 

87 

14.4 

14.6 

14.2 

13.2* 

12.9* 

90 Days 

0 

25 

125 

2,500 

5,000 

10/10 

10/10 

10/10 

10/10 

10/10 

197 ± 7 

199 ± 6 

194 ± 6 

211 ± 8 

212 ± 10 

337 ± 20 

340 ± 13 

341 ± 13 

334 ± 18 

317 ± 34 

140 ± 19 

142 ± 11 

146 ± 14 

123 ± 14* 

105 ± 28** 

101 

104 

88 

75 

13.4 

13.4 

14.1* 

14.1* 

13.7* 

* Significantly different (P#0.05) from the control group by Dunnett’s test 

** P#0.02 a Number of animals surviving/number initially in group b	 Weights and weight changes are given as mean ± standard deviation. 

Feed consumption is given as grams consumed per animal per day. 
182 

c 

Oxazepam, NTP TR 468 

TABLE H2 

BrdU and Proliferating Cell Nuclear Antigen Labeling Indices, Liver Weight/Body Weight Ratios, 

and Total Body Burden of Male F344/N Rats Administered Oxazepam in Feed for 90 Daysa 

Concentration 

(ppm) 

Number 

of Rats 

BrdU 

Labeling 

Indexb 

Fold 

Increase 

Over 

Control 

PCNA 

Labeling 

Index 

Fold 

Increase 

Over 

Control 

Liver Weight/ 

Body Weight 

(%) 

Total 

Cumulative 

Dosec 

(mg/kg) 

15 Days 

0 

25 

125 

2,500 

5,000 

10 

10 

10 

10 

10 

3.18 ± 1.3 

1.42 ± 0.7 

1.94 ± 0.2 

11.1 ± 7.3* 

16.7 ± 7.7** 

0.45 

0.61 

3.49 

5.25 

0.5 ± 0.3 

0.4 ± 0.2 

0.2 ± 0.1 

1.2 ± 0.7* 

1.2 ± 0.5* 

0.8 

0.4 

2.4 

2.4 

4.0 ± 0.2 

3.9 ± 0.1 

3.9 ± 0.2 

4.9 ± 0.2** 

5.6 ± 0.3** 

19 

101 

1,868 

3,155 

30 Days 

0 

25 

125 

2,500 

5,000 

10 

10 

10 

10 

10 

0.4 ± 0.2 

0.5 ± 0.3 

0.5 ± 0.2 

1.4 ± 1.4* 

3.7 ± 1.8** 

1.25 

1.25 

3.50 

9.25 

0.1 ± 0.1 

0.3 ± 0.3 

0.3 ± 0.2* 

0.6 ± 0.3* 

0.6 ± 0.4* 

3.0 

3.0 

6.0 

6.0 

3.7 ± 0.2 

3.9 ± 0.2 

3.8 ± 0.2 

4.9 ± 0.3** 

5.5 ± 0.2** 

37 

186 

3,641 

7,105 

45 Days 

0 

25 

125 

2,500 

5,000 

10 

10 

10 

10 

10 

2.6 ± 0.7 

1.0 ± 0.7 

1.6 ± 1.7 

3.3 ± 1.4 

3.4 ± 1.2 

2.60 

0.62 

1.27 

1.31 

0.8 ± 0.4 

0.4 ± 0.3 

0.7 ± 0.4 

0.3 ± 0.2 

0.3 ± 0.2 

0.5 

0.9 

0.4 

0.4 

3.5 ± 0.2 

3.8 ± 0.1** 

3.9 ± 0.2** 

4.7 ± 0.2** 

5.5 ± 0.2** 

53 

260 

5,086 

10,150 

90 Days 

0 

25 

125 

2,500 

5,000 

10 

10 

10 

10 

10 

1.4 ± 0.3 

1.4 ± 0.5 

1.2 ± 0.4 

0.6 ± 0.2 

0.8 ± 0.4 

1.00 

0.86 

0.43 

0.57 

0.2 ± 0.1 

0.1 ± 0.1 

0.2 ± 0.1 

0.2 ± 0.2 

0.3 ± 0.1 

0.5 

1.0 

1.0 

1.5 

3.3 ± 0.1 

3.3 ± 0.2 

3.4 ± 0.1 

4.5 ± 0.2** 

5.1 ± 0.3** 

89 

466 

9,501 

19,448 

* Significantly different (P#0.05) from the control group by Dunnett’s test 

** P#0.01 a Labeling indices and liver weight data are presented as mean ± standard deviation. BrdU=bromodeoxyuridine; PCNA=proliferating cell 

nuclear antigen b Number of hepatocytes with labeled nuclei/1,000 hepatocytes scored 

Data are calculated as (oxazepam concentration)(feed consumption)(days on study)/final mean body weight. 
183 

TABLE H3

Clinical Chemistry Data for Male F344/N Rats Administered Oxazepam in Feed for 90 Days a 

Concentration AP ALT CK SDH 5'N Bile Acids Albumin Protein Creatinine Cholesterol

(ppm) (IU/L) (IU/L) (IU/L) (IU/L) (IU/L) (μmol/L) (g/dL) (g/dL) (mg/dL) (mg/dL) 

15 Days

0 (n=10) 143 ± 8 44 ± 9.4 136 ± 43 21 ± 10 26 ± 1.5 30 ± 6.8 4.5 ± 0.3 7.5 ± 0.4 0.91 ± 0.07 70 ± 6 

25 (n=10) 146 ± 13 38 ± 3.0 342 ± 116 14 ± 3.4* 28 ± 1.4 33 ± 8.4 4.7 ± 0.4 7.4 ± 0.3 0.94 ± 0.05 67 ± 5 

125 (n=9) 136 ± 12 33 ± 2.8 217 ± 113 12 ± 3.0** 27 ± 2.4 28 ± 4.8 4.6 ± 0.2 7.2 ± 0.6 0.85 ± 0.07 64 ± 4 

2,500 (n=10) 145 ± 11 42 ± 5.4 199 ± 48 17 ± 2.1 30 ± 3.0** 32 ± 9.5 4.7 ± 0.2 7.6 ± 0.3 0.79 ± 0.03** 60 ± 6 5,000 (n=10) 176 ± 19** 44 ± 4.4 135 ± 54 19 ± 2.1 35 ± 4.0** 35 ± 14 4.8 ± 0.3 7.7 ± 0.2 0.74 ± 0.05** 71 ± 18 

30 Days

0 (n=10) 130 ± 6 47 ± 6.5 195 ± 66 17 ± 3.4 28.7 ± 4.9 28 ± 6 4.2 ± 0.2 7.2 ± 0.6 0.84 ± 0.1 74 ± 7 

25 (n=10) 128 ± 6 41 ± 4.2** 161 ± 81 18 ± 3.1 29.5 ± 2.5 26 ± 6 4.3 ± 0.2 7.5 ± 0.4 0.72 ± 0.08* 68 ± 6 

125 (n=9) 115 ± 11 37 ± 2.4** 152 ± 66 15 ± 2.7 26.3 ± 1.7 25 ± 7 4.0 ± 0.2 7.4 ± 0.3 0.72 ± 0.1* 62 ± 5** 

2,500 (n=10) 119 ± 9* 32 ± 1.8** 310 ± 99* 14 ± 1.7 23.9 ± 1.0 32 ± 8 4.2 ± 0.2 7.7 ± 0.2* 0.68 ± 0.04** 50 ± 4** 5,000 (n=10) 122 ± 10 28 ± 4.5** 188 ± 88 15 ± 1.7 36.2 ± 24 40 ± 12** 4.5 ± 0.2** 7.8 ± 0.3** 0.62 ± 0.09** 51 ± 11** 

45 Days

0 (n=10) 117 ± 6 54 ± 7.9 150 ± 59 27 ± 7.7 27.0 ± 1.3 26 ± 5 4.1 ± 0.2 7.5 ± 0.3 0.96 ± 0.05 70 ± 3 

25 (n=10) 116 ± 7 52 ± 10 235 ± 66** 25 ± 7.3 30.2 ± 2.3** 25 ± 4 4.3 ± 0.2 7.4 ± 0.5 1.05 ± 0.08* 73 ± 6 

125 (n=10) 113 ± 5 42 ± 5.0** 148 ± 27 23 ± 5.5 29.8 ± 1.5* 23 ± 8 4.2 ± 0.3 7.5 ± 0.3 0.91 ± 0.06 71 ± 7 

2,500 (n=10) 114 ± 11 34 ± 4.8** 105 ± 23 19 ± 3.3** 30 ± 3.2 30 ± 8 4.3 ± 0.4 7.0 ± 0.5* 0.83 ± 0.05** 66 ± 14 5,000 (n=10) 115 ± 11 35 ± 7.1** 194 ± 84 16 ± 2.3** 31 ± 2.2** 27 ± 12 4.6 ± 0.4* 7.0 ± 0.4* 0.88 ± 0.08* 58 ± 6** 

90 Days

0 (n=10) 113 ± 6 62 ± 22 291 ± 71 24 ± 13 29 ± 1.3 28 ± 10 3.7 ± 0.1 7.5 ± 0.2 1.07 ± 0.07 76 ± 6 

25 (n=10) 94 ± 8** 47 ± 6* 162 ± 65* 18 ± 3 29 ± 1.2 26 ± 9 3.7 ± 0.2 7.2 ± 0.2 0.91 ± 0.03** 75 ± 5 

125 (n=10) 92 ± 6** 46 ± 5* 183 ± 110* 17 ± 3 29 ± 1.9 32 ± 10 3.8 ± 0.4 7.3 ± 0.3 0.89 ± 0.06** 74 ± 7 

2,500 (n=10) 107 ± 5 39 ± 6** 317 ± 111 15 ± 4** 26 ± 1.5** 25 ± 6 4.0 ± 0.1** 7.9 ± 0.2** 0.93 ± 0.05** 57 ± 5** 5,000 (n=10) 92 ± 22** 36 ± 8** 281 ± 96 16 ± 3* 28 ± 1.4 28 ± 8 4.2 ± 0.2** 8.1 ± 0.4** 0.87 ± 0.07** 61 ± 8** 

* Significantly different (P#0.05) from the control group by Dunnett’s test** P#0.01

a Data are presented as mean ± standard deviation. AP=alkaline phosphatase; ALT=alanine aminotransferase; CK=creatine kinase; SDH=sorbitol dehydrogenase; 5 NN=5N-nucleotidase

Oxazepam, NTP TR 468
 
184 Oxazepam, NTP TR 468 

TABLE H4 

Serum Oxazepam Concentrations in Male F344/N Rats Administered Oxazepam in Feed for 90 Daysa 

Concentration 

(ppm) 

15 Days 30 Days 45 Days 90 Days 

25 

125 

2,500 

5,000 

0.03 ± 0.02 

0.07 ± 0.02 

0.70 ± 0.13 

2.64 ± 0.90 

0.04 ± 0.01 

0.07 ± 0.02 

0.39 ± 0.16 

1.31 ± 0.37 

0.02 ± 0.01 

0.12 ± 0.01 

0.52 ± 0.27 

1.37 ± 0.23 

0.03 ± 0.01 

0.08 ± 0.03 

3.05 ± 0.16 

3.63 ± 1.38 

a Values are expressed in Fg/mL serum ± standard deviation for groups of 10 animals. Limit of quantification=0.025 μg/mL