149 
 
Guidance for Industry 
 
 
Studies to Evaluate the Safety of Residues of 
Veterinary Drugs in Human Food: 
General Approach to Testing  
VICH GL33 
 
(This version of the guidance replaces the version that was made available in June 
27, 2006. This guidance document has been revised by inserting a reference to the 
3 Rs Principle (Refine, Reduce and Replace), highlighting the VICH adherence to 
the goal of minimizing animal testing. 
 
FINAL GUIDANCE 
 
This final guidance outlines a testing approach to assure human food safety 
following the consumption of food products derived from animals treated with 
veterinary drugs. 
 
Comments and suggestions regarding the document should be submitted to 
Division of Dockets Management (HFA-305), Food and Drug Administration, 
5630 Fishers Lane, Rm. 1061, Rockville, MD  20852. Submit electronic 
comments to http://www.regulations.gov.  All comments should be identified with 
the Docket No. 2002D-0326.   
 
For questions regarding this document, contact the Division of Human Food 
Safety, Center for Veterinary Medicine, (HFV-150), Food and Drug 
Administration, 7500 Standish Place, Rockville, MD 20855, 240-276-8208. 
 
U.S. Department of Health and Human Services 
Food and Drug Administration 
Center for Veterinary Medicine 
March 17, 2009 
  Contains Non-Binding Recommendations 
     
 
 
VICH GL33 (SAFETY: GENERAL APPROACH) 
October 2002 
For implementation at Step 7 - Final 
 
 
 
 
 
Studies to Evaluate  
the Safety of Residues of 
 Veterinary Drugs in Human 
 Food: 
General Approach  
To Testing 
 
 
 
 
Recommended for Implementation 
on October 2002 
by the VICH Steering Committee 
 
 
 
 
 
 
 
 
 
THIS GUIDANCE HAS BEEN DEVELOPED BY THE APPROPRIATE VICH EXPERT WORKING GROUP AND 
WAS SUBJECT TO CONSULTATION BY THE PARTIES, IN ACCORDANCE WITH THE VICH PROCESS. AT 
STEP 7 OF THE PROCESS THE FINAL DRAFT IS RECOMMENDED FOR ADOPTION TO THE REGULATORY 
BODIES OF THE EUROPEAN UNION, JAPAN AND USA. 
 
 
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STUDIES TO EVALUATE THE SAFETY OF RESIDUES OF 
VETERINARY DRUGS IN HUMAN FOOD: GENERAL 
APPROACH TO TESTING 
 
 
Table of Contents 
 
 
1. INTRODUCTION..............................................................................................4 
1.1. OBJECTIVE OF THE GUIDANCE...................................................................................4 
1.2. BACKGROUND...........................................................................................................5 
1.3. SCOPE OF THE GUIDANCE.........................................................................................5 
2. GUIDANCE.......................................................................................................6 
2.1. BASIC TESTS............................................................................................................6 
2.1.1. Repeat-dose toxicity testing (VICH GL31 and VICH GL37).............................6 
2.1.2. Reproduction toxicity testing (VICH GL22).......................................................6 
2.1.3. Developmental toxicity testing (VICH GL32)....................................................6 
2.1.4. Genotoxicity testing (VICH GL23) ....................................................................6 
2.2. ADDITIONAL TESTS....................................................................................................7 
2.2.1. Testing for effects on the human intestinal flora    (VICH GL36)......................7 
2.2.2. Pharmacological effects testing........................................................................7 
2.2.3. Immunotoxicity testing......................................................................................7 
2.2.4. Neurotoxicity testing.........................................................................................7 
2.2.5. Carcinogenicity testing (VICH GL28)................................................................7 
2.3. SPECIAL TESTS.........................................................................................................7 
3. REFERENCES.................................................................................................8 
 
 
 
 
 
 
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Studies to Evaluate the Safety of Residues of Veterinary 
Drugs in Human Food: General Approach to Testing 
 
 
This  guidance  represents  the  Food  and  Drug  Administrations  (FDAs)  current  thinking  for 
establishing the safety of veterinary drug residues in human food.   It does not create or confer any 
rights for or on any person and does not operate to bind FDA or the public.  You can use an 
alternative approach if the approach satisfies the requirements of the applicable statute(s) and/or 
regulation(s).  If you want to discuss an alternative approach, contact the FDA staff responsible for 
implementing this guidance.  If you cannot identify the appropriate FDA staff, call the appropriate 
number listed on the title page of this guidance.  
 
 
1. INTRODUCTION 
 
1.1. Objective of the guidance 
 
This guidance outlines a recommended testing approach to assure the safety of human 
food derived from animals treated with veterinary drugs. The tests should provide an 
adequate amount of toxicological data to ensure human food safety, while reducing the 
number of animals used in testing and conserving resources.  
 
 
FDAs guidance documents, including this guidance, do not establish legally 
enforceable responsibilities.  Instead, guidances describe the Agencys current 
thinking on a topic and should be viewed only as recommendations, unless 
specific regulatory or statutory requirements are cited.  The use of the word 
should in Agency guidances means that something is suggested or 
recommended, but not required. 
 
VICH seeks to minimize animal testing by supporting the 3Rs principle -Refinement 
(lessen or eliminate pain or distress in animals), Reduction (lower the number of test 
animals needed) of animals in research, and Replacement (replace with non-animal 
system or with phylogenectically lower species).  
 
One of the expressed goals of VICH is to strive to eliminate repetitious and unnecessary 
testing through harmonization of regulatory requirements for the registration of veterinary 
products, a goal that undoubtedly leads to a reduction in the number of animals used for 
product development and registration. Whenever possible, flexibility, minimum number of 
animals, as well as alternative in vivo and in vitro tests have been recommended. 
 
When designing and carrying out the studies recommended below due regard for the 
welfare of the study animals should be given.  The use of animals in the studies 
described below should adhere to these protocols and should conform to general ethical 
standards and to the national standards for the use and care of experimental animals.  
 
While the validation of alternative testing protocols falls outside its remit, VICH 
recognizes that the international status and influence of VICH provide a unique 
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opportunity to encourage the use of validated alternative methods1. To this end, the 
Safety EWG that developed these guidances involving animal experimentation has 
exercised its responsibility to consider animal welfare, and particularly the possibilities 
for replacement, refinement and reduction of animal testing. 
 
VICH periodically reviews its guidances to take into account the development of 
alternative testing protocols that have been validated, and amends its guidances where 
appropriate to assure that they conform to the most recent alternative testing 
developments. 
 
 
1.2. Background 
 
The hazards associated with the consumption of food containing residues of veterinary 
drugs are generally assessed in laboratory animals treated with the drugs. International 
harmonization of testing requirements aims to assure that the development and 
registration of valuable animal drugs is achieved with maximum efficiency. The efficiency 
of the approval process has an impact on the expenditure of resources, time from 
discovery to new product approval, and the introduction of innovative drugs into the 
market.  
 
Current toxicological testing for veterinary drugs are based on the toxicological tests for 
human medicines, food additives and pesticides. This guidance suggests use of those 
tests particularly relevant to the identification of a no-observed adverse effect level 
(NOAEL) for veterinary drugs. 
 
The appropriateness of a test for the purpose of assessing human food safety is 
determined by its ability to predict an adverse effect in humans. The recommendation of 
concise and appropriate tests was of major concern.  A recommended testing regimen 
was selected based on a minimum number of tests after consideration of extensive 
historical data and a review of widely accepted protocols. To increase the chance of 
identifying a potential adverse effect, both rodent and non-rodent models should be 
included in the testing approach. Additional studies, such as tests for effects on human 
intestinal flora, may be used to evaluate compound specific endpoints.  The 
recommended testing approach is designed to determine a dose that causes an adverse 
effect and a dose that can be identified as the NOAEL.  A NOAEL is used to establish a 
human acceptable daily intake (ADI), which represents the amount of drug that can be 
safely consumed by a person on a daily basis for a lifetime.  
 
 
1.3. Scope of the guidance 
 
The scope of this guidance includes: 1) basic tests recommended for all new animal 
drugs used in food-producing animals in order to assess the safety of drug residues 
present in human food, 2) additional tests that may be recommended depending on 
specific toxicological concerns such as those associated with the structure, class, and 
                                                           
1 Validation of alternative testing protocols is the responsibility of regional bodies; ECVAM in 
Europe, ICCVAM in the USA and JaCVAM in Japan. 
 
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mode of action of the drug, and 3) special tests which might be recommended to assist 
in the interpretation of data obtained in the basic or additional tests. 
 
Guidance on the design of protocols for basic and selected additional tests will be 
provided in separate VICH guidances. Selection and protocol design of special tests and 
any other tests will be left to the discretion of the various regulatory authorities and/or 
drug sponsors.  
 
2. GUIDANCE 
 
Testing should include an assessment of systemic toxicity, reproduction toxicity, 
developmental toxicity, genotoxicity, carcinogenicity, and effects on the human intestinal 
flora. In general, oral administration is the route of choice for in vivo tests. The guidances 
do not preclude the possibility of alternative approaches that may offer an equivalent 
assurance of safety, including scientifically based reasons as to why such data may not 
need to be provided. Testing described in this guidance should be conducted pursuant 
to national standards and/or compliance with Good Laboratory Practice.     
 
2.1. Basic tests 
 
2.1.1. Repeat-dose toxicity testing (VICH GL31 and VICH GL37)5,8 
 
Repeat-dose toxicity testing should be performed to define (1) toxic effects based on 
repeated and/or cumulative exposures to the compound and/or its metabolites, (2) the 
incidence and severity of the effect in relation to dose and/or duration of exposure, (3) 
doses associated with toxic and biological responses, and (4) a NOAEL.   
 
2.1.2. Reproduction toxicity testing (VICH GL22)2 
 
Multigeneration reproduction studies are recommended and are designed to detect any 
effect on mammalian reproduction. These include effects on male and female fertility, 
mating, conception, implantation, ability to maintain pregnancy to term, parturition, 
lactation, survival, growth and development of the offspring from birth through to 
weaning, sexual maturity and the subsequent reproductive function of the offspring as 
adults. 
 
2.1.3. Developmental toxicity testing (VICH GL32)6  
 
Developmental toxicity testing should be used to detect any adverse effects on the 
pregnant female and development of the embryo and fetus consequent to exposure of 
the female from implantation through the entire period of gestation to the day before 
caesarean section. Such adverse effects include enhanced toxicity relative to that 
observed in non-pregnant females, embryo-fetal death, altered fetal growth, and 
structural changes to the fetus. 
 
2.1.4. Genotoxicity testing (VICH GL23)3 
 
A battery of genotoxicity tests should be used to identify substances that have the 
capacity to damage the genetic information within cells. Substances that are considered 
to be genotoxic should be regarded as potential carcinogens. Those that cause genetic 
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damage in germ cells also have the potential to cause reproductive/developmental 
effects.   
 
 
2.2. Additional tests 
 
These tests are recommended to address safety concerns such as those based on 
compound structure, class, and mode of action. Some examples of these studies are: 
 
2.2.1. Testing for effects on the human intestinal flora    (VICH GL36)7 
 
For compounds with antibacterial properties, information to determine the effects of 
residues of the drug on the human intestinal flora is recommended. 
 
2.2.2. Pharmacological effects testing   
 
Some veterinary drugs produce pharmacological effects in the absence of a toxic 
response or at doses lower than those required to elicit toxicity. The pharmacological 
NOAEL should be identified and taken into account in the setting of the ADI for the drug. 
 
2.2.3. Immunotoxicity testing   
 
For some classes of drugs such as beta-lactam antibiotics, the potential for the drug to 
elicit an allergic reaction in sensitive individuals should be investigated. Immunotoxicity 
testing may be appropriate for other veterinary drugs when the results from other tests 
indicate a potential immunological hazard. 
 
2.2.4. Neurotoxicity testing  
 
If evidence of a neurotoxic potential is identified in repeat-dose tests, further testing, 
such as that recommended in OECD Test Guideline 424 Neurotoxicity Study in 
Rodents may be recommended. 
 
  
2.2.5. Carcinogenicity testing (VICH GL28)4 
 
For compounds that are suspected to have carcinogenic potential, carcinogenicity 
testing by the oral route is recommended. The decision to recommend carcinogenicity 
testing is based on all available data including results of genotoxicity testing, structure 
activity relationship (SAR) information and results of repeat-dose and mechanistic 
studies. It is recommended that carcinogenicity testing be performed using a 
carcinogenicity bioassay. However, information derived from a combined assay for 
carcinogenicity and chronic toxicity may also be acceptable.  
 
2.3. Special tests  
 
Special tests, performed to understand the mode of action of the drug and used to aid in 
the interpretation of, or the assessment of the relevance of the data obtained in the basic 
and/or additional tests, may also be recommended. 
 
 
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3. REFERENCES 
 
1.  OECD. 1997. Test Guideline 424. Neurotoxicity Study in Rodents. In: OECD 
     Guidelines for the Testing of Chemicals. Organization for Economic Cooperation &  
     Development, Paris. 
 
2.  VICH (2001). VICH Harmonized Tripartite Guideline GL22. Studies to Evaluate the 
     Safety of Residues of Veterinary Drugs in Human Food: Reproduction Toxicity 
     Testing. International Cooperation on Harmonisation of Technical Requirements for 
     Registration of Veterinary Medicinal Products.   
 
3.  VICH (2001). VICH Harmonized Tripartite Guideline GL23. Studies to Evaluate the 
     Safety of Residues of Veterinary Drugs in Human Food: Genotoxicity Testing. 
     International Cooperation on Harmonisation of Technical Requirements for 
     Registration of Veterinary Medicinal Products.   
 
4.  VICH (2002). VICH Harmonized Tripartite Guideline GL28. Studies to Evaluate the 
     Safety of Residues of Veterinary Drugs in Human Food: Carcinogenicity Testing. 
     International Cooperation on Harmonisation of Technical Requirements for 
     Registration of Veterinary Medicinal Products.   
 
5.  VICH (2002). VICH Harmonized Tripartite Guideline GL31. Studies to Evaluate the 
     Safety of Residues of Veterinary Drugs in Human Food: Repeat-Dose (90-Day) 
     Toxicity Testing. International Cooperation on Harmonisation of Technical 
     Requirements for Registration of Veterinary Medicinal Products.   
 
6.  VICH (2002). VICH Harmonized Tripartite Guideline GL32. Studies to Evaluate the 
     Safety of Residues of Veterinary Drugs in Human Food: Developmental Toxicity 
     Testing. International Cooperation on Harmonisation of Technical Requirements for 
     Registration of Veterinary Medicinal Products.   
 
7.  VICH (2004).  VICH Harmonized Tripartite Guideline GL36. Studies to Evaluate the 
     Safety of Residues of Veterinary Drugs in Human Food: General Approach to 
     Establish a Microbiological ADI. International Cooperation on Harmonisation of 
     Technical Requirements for Registration of Veterinary Medicinal Products.   
   
8.  VICH (2004).  VICH Harmonized Tripartite Guideline GL37. Studies to Evaluate the 
     Safety of Residues of Veterinary Drugs in Human Food: Repeat-Dose (Chronic) 
     Toxicity Testing. International Cooperation on Harmonisation of Technical 
     Requirements for Registration of Veterinary Medicinal Products.     
 
  
 
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