Guidance for Industry
Pharmacokinetics in Patients with
Impaired Hepatic Function: Study
Design, Data Analysis, and
Impact on Dosing and Labeling
U.S. Department of Health and Human Services
Food and Drug Administration
Center for Drug Evaluation and Research (CDER)
Center for Biologics Evaluation and Research (CBER)
May 2003
Clinical Pharmacology Guidance for Industry
Pharmacokinetics in Patients with
Impaired Hepatic Function: Study
Design, Data Analysis, and
Impact on Dosing and Labeling
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U.S. Department of Health and Human Services
Food and Drug Administration
Center for Drug Evaluation and Research (CDER)
Center for Biologics Evaluation and Research (CBER)
May 2003
Clinical Pharmacology Contains Nonbinding Recommendations
TABLE OF CONTENTS
I.  INTRODUCTION.................................................................................................................1
II. BACKGROUND...................................................................................................................2
III. DECIDING WHETHER TO CONDUCT A STUDY IN PATIENTS WITH
IMPAIRED HEPATIC FUNCTION..........................................................................................3
A. When Studies May Be Important.................................................................................................3
B. When Studies May Not Be Important..........................................................................................3
IV. STUDY CONSIDERATIONS..............................................................................................3
A Basic Full Study Design.................................................................................................................3
B. Reduced Study Design....................................................................................................................4
1. Study Participants............................................................................................................................4
2. Drug Administration........................................................................................................................5
3. Sample Collection and Analysis.......................................................................................................5
C.  Population PK Approach..............................................................................................................6
D. Pharmacodynamic Assessments...................................................................................................6
V. DATA ANALYSIS................................................................................................................6
A. Parameter Estimation....................................................................................................................6
B. Relationship Between Measures of Hepatic Function and PK..................................................7
C.  Development of Dosing Recommendations..................................................................................7
VI. LABELING............................................................................................................................8
A. Clinical Pharmacology...................................................................................................................8
1. Pharmacokinetics Section................................................................................................................8
2. Special Populations Section.............................................................................................................9
B. Precautions/Warnings.................................................................................................................11
C. Dosage and Administration:.......................................................................................................11
REFERENCES............................................................................................................................13
APPENDIX:  ASSESSMENT OF LIVER FUNCTION..........................................................14 Contains Nonbinding Recommendations
1
Guidance for Industry
Pharmacokinetics in Patients with Impaired Hepatic Function:
Study Design, Data Analysis, and Impact on Dosing and Labeling
This guidance represents the Food and Drug Administration's (FDA's) current thinking on this topic.  It
does not create or confer any rights for or on any person and does not operate to bind FDA or the public. 
An alternative approach may be used if such approach satisfies the requirements of the applicable statutes
and regulations.  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.
I.  INTRODUCTION
This guidance provides recommendations to sponsors and applicants who plan to conduct studies
to assess the influence of hepatic impairment on the pharmacokinetics (PK) and, where
appropriate, the pharmacodynamics (PD) of a drug, including therapeutic biological products. 
This guidance discusses:
  When studies should and should not be conducted
  Recommended design and conduct of studies to characterize the effects of impaired
hepatic function on the PK of a drug
  Inclusion criteria for patient populations to be studied
  Analysis, interpretation, and reporting of the results of the studies and description of the
results in labeling
The guidance does not consider ways to assess the safety and efficacy of a drug to treat hepatic
disease or how to assess whether a drug causes hepatotoxicity.
FDA's guidance documents, including this guidance, do not establish legally enforceable
responsibilities.  Instead, guidances describe the Agency's 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.
                                                
1 This guidance has been prepared by the Hepatic Impairment Working Group in the Clinical Pharmacology Section
of the Medical Policy Coordinating Committee in the Center for Drug Evaluation and Research (CDER) at the Food
and Drug Administration, with contributions from the Center for Biologics Evaluation and Research (CBER).
1 Contains Nonbinding Recommendations
II. BACKGROUND
The liver is involved in the clearance of many drugs through a variety of oxidative and
conjugative metabolic pathways and/or through biliary excretion of unchanged drug or
metabolites.  Alterations of these excretory and metabolic activities by hepatic impairment can
lead to drug accumulation or, less often, failure to form an active metabolite.
Many reports in the biomedical literature have documented that hepatic disease can alter the
absorption and disposition of drugs (PK) as well as their efficacy and safety (PD).  These reports
have been based on studies in patients with common hepatic diseases, such as alcoholic liver
disease and chronic infections with hepatitis viruses B and C, and less common diseases, such as
acute hepatitis D or E, primary biliary cirrhosis, primary sclerosing cholangitis, and alpha -
1
antitrypsin deficiency.  Liver disease may also alter kidney function, which can lead to
accumulation of a drug and its metabolites even when the liver is not primarily responsible for
elimination.  Liver disease may also alter PD effects (e.g., increased encephalopathy with certain
drugs in patients with hepatic failure).  The specific impact of any disease on hepatic function is
often poorly described and highly variable, particularly with regard to effects on the PK and PD
of a drug.
Measurements such as creatinine or creatinine clearance have been used successfully to adjust
dosing regimens for drugs eliminated primarily by the kidneys.  Similar measures of hepatic
function have been sought using endogenous substances affected by the liver such as bilirubin
and albumin, or functional measures such as prothrombin time, or the ability of the liver to
eliminate marker substrates such as antipyrine (Figg et al., 1995), indocyanine green (ICG) (Figg
et al., 1995), monoethylglycine-xylidide (MEGX) (Testa et al., 1997), and galactose (Tang and
Hu 1992).  Clinical variables have also been studied.  These include ascites or encephalopathy,
nutritional status, peripheral edema, and histologic evidence of fibrosis or combinations of
variables such as the Child-Pugh classification for alcoholic cirrhosis and portal hypertension
(Zakim and Boyer 1996; Pugh et al., 1973), the Mayo risk scores for primary biliary cirrhosis
and primary sclerosing cholangitis (Dickson et al., 1989; Wiesner et al., 1989), and the Maddrey-
Carithers discriminant function for acute alcoholic hepatitis (Maddrey et al., 1978; Carithers et
al., 1989) (see Appendix).  Despite extensive efforts, no single measure or group of measures has
gained widespread clinical use to allow estimation in a given patient of how hepatic impairment
will affect the PK and/or PD of a drug.
Even though clinically useful measures of hepatic function to predict drug PK and PD are not
generally available, clinical studies in patients with hepatic impairment, usually performed
during drug development, can provide information that may help guide initial dosing in patients.
This information can be appropriately used with the understanding that careful observation and
dose titration are critical to achieve the optimal dose in any given patient.
2 Contains Nonbinding Recommendations
III. DECIDING WHETHER TO CONDUCT A STUDY IN PATIENTS WITH
IMPAIRED HEPATIC FUNCTION
A. When Studies May Be Important
This guidance recommends a PK study in patients with impaired hepatic function if
hepatic metabolism and/or excretion accounts for a substantial portion (>20 percent of
the absorbed drug) of the elimination of a parent drug or active metabolite.  The guidance
also recommends a hepatic impairment study even if the drug and/or active metabolite is
eliminated to a lesser extent (<20 percent), if its labeling or literature sources suggest that
it is a narrow therapeutic range drug.2  If the metabolism of the drug is unknown and
other information is lacking to suggest that hepatic elimination routes are minor, the
Agency recommends that the drug be considered extensively metabolized.
B. When Studies May Not Be Important
For some drugs, hepatic functional impairment is not likely to alter PK sufficiently to
require dosage adjustment.  In such cases, a study to confirm the prediction is generally
not important.  The following drug properties may support this conclusion:
  The drug is excreted entirely via renal routes of elimination with no involvement
of  the liver.
  The drug is metabolized in the liver to a small extent (<20 percent), and the
therapeutic range of the drug is wide, so that modest impairment of hepatic
clearance will not lead to toxicity of the drug directly or by increasing its
interaction with other drugs.
  The drug is gaseous or volatile, and the drug and its active metabolites are
primarily eliminated via the lungs.
For drugs intended only for single-dose administration, a hepatic impairment study  will
generally not be useful, unless clinical concerns suggest otherwise.
IV. STUDY CONSIDERATIONS
The following sections of the guidance focus on a basic full study design (Section A), a reduced
study design (Section B), and a population PK approach (Section C).
A Basic Full Study Design
To develop specific dosing recommendations across the entire spectrum of hepatic
impairment, a study should be carried out in patients in the three Child-Pugh categories,
mild, moderate and severe, as well as controls.  For this study design to provide evaluable
                                                
2 The therapeutic range (TR) can be derived from the concentration- or dose-response data existing in the safety and
efficacy database preapproval or from data obtained postapproval.
3 Contains Nonbinding Recommendations
data, at least six subjects in each arm should be evaluated and all other considerations set
forth in section B should be taken into account.
B. Reduced Study Design
1. Study Participants
An FDA survey of 57 PK studies in patients with hepatic impairment in new drug
applications submitted between 1995 and 1998 revealed that 55 percent used the Child-
Pugh scale to assess hepatic impairment.  Of the 57 studies surveyed, 19 estimated oral
drug clearance in normals and in patients in more than one Child-Pugh category (i.e.,
mild, moderate, or severe).  Of those 19 studies, 17 demonstrated a negative correlation
(r2 between 0.5 to 1.0) between oral drug clearance and hepatic impairment, and 16
showed impaired hepatic metabolism in the patients in the moderate Child-Pugh
category.
Based on these data, this guidance recommends that the Child-Pugh classification be
used to categorize the degree of hepatic impairment in patients, just as serum creatinine
or creatinine clearance is used to categorize varying degrees of renal impairment.  In
patients evaluated for this purpose, it is important that impaired hepatic function  not
some other underlying disease  be the cause of alterations in the Child-Pugh
components (bilirubin, albumin, prothrombin, encephalopathy and ascities).  For
example, in patients with metastatic cancer, hypoalbuminemia, encephalopathy, and
ascites may be related to cancer cachexia or cancer metastatic to the brain or peritoneal
surfaces rather than impaired hepatic function.  Other approaches to assess varying
degrees of hepatic impairment may be appropriate, but a Child-Pugh categorization
should still be included for each patient.
Also, based on the above data, a study design involving control subjects and patients with
a Child-Pugh category of moderate would generally be appropriate.  In that case, the
findings in the moderate category would be applied to patients with a mild Child-Pugh
category, and dosing in the severe category would generally be contraindicated (see the
Labeling section for details).
The primary purpose of this guidance is to help sponsors and applicants determine, based
on the behavior of the drug in patients with normal liver function, whether the PK and/or
PD of a drug and its active metabolites are altered in patients with hepatic impairment to
the extent that an adjustment to the dosage would be indicated.  For this reason, the
control group should be derived from the intended patient population (with apparently
normal hepatic function), not from young, healthy volunteers.  To the extent possible, the
control group should be similar to patients with respect to age, weight, and gender. 
Depending on the drug, consideration is also recommended of other factors with
significant potential to affect the PK of a drug to be studied (e.g., diet, smoking, alcohol
intake, concomitant medications, ethnicity).  If concomitant medications are used in the
patients being studied, a careful assessment of their influence on PK or PD  should be
made at the time of data analysis.  For drugs whose metabolism is mediated by enzymes
4 Contains Nonbinding Recommendations
known to exhibit genetic polymorphism (e.g., CYP450, 2D6, or 2C19), the sponsor
should take into consideration the metabolic status of the enrolled subjects when
analyzing the results of the study.  In addition to standard clinical tests performed prior to
entry, sponsors and applicants are urged to perform assessments of hepatic blood flow
and/or intrinsic clearance using appropriate markers.
A sufficient number of subjects should be enrolled in the study to provide evaluable data
from at least eight subjects in the control and the moderate impairment arms.
2. Drug Administration
A clinical study to investigate the effects of hepatic impairment on drug disposition can
be designed, depending on circumstances, as a single-dose or multiple-dose study with
PK assessment of the parent drug and any active metabolite(s).  In a multiple-dose study,
PK assessment is appropriately carried out at steady state.  A single-dose study may be
satisfactory for cases where prior evidence indicates that multiple-dose PK is accurately
predicted by single-dose data for both parent drug and active metabolites.  This would be
the case when the drug and active metabolites exhibit linear and time-independent PK at
the concentrations anticipated in the patients to be studied.  A multiple-dose study is
desirable when the drug or an active metabolite is known to exhibit nonlinear or time-
dependent PK.  Although the planned clinical dose is generally recommended as the
appropriate dose to be used in the study, a reduced dose may be appropriate in patients
with hepatic impairment if concern exists about drug toxicity in patients with increased
blood levels.  If more than one route of administration is proposed for a drug, the study
should use the route that provides the maximum information regarding the impact of
hepatic impairment on the candidate drugs elimination.
3. Sample Collection and Analysis
The blood sampling duration should be adequate to determine the terminal half-life of the
drug and its active metabolite(s), with the expectation that these times may be extended
in the patient compared to the control population.  For drugs that are highly extracted by
the liver (extraction ratio > 0.7) and that are extensively bound to plasma proteins
(fraction unbound < 10 percent), the Agency recommends that the unbound fraction be
determined at least at trough and maximum plasma concentration.  The clearance and
volume parameters are appropriately expressed in terms of both unbound and total
concentrations of drug in plasma/serum/blood. To allow for analysis of the parent drug
and its active metabolite(s), analytical methods should exhibit sufficient sensitivity and
specificity.  For drugs with stereochemical properties, stereoselectivity in drug
metabolism and protein binding of enantiomers merit consideration (FDA 1992).
5 Contains Nonbinding Recommendations
C.  Population PK Approach
Population PK screening in phases 2 and 3 can be useful in assessing the impact of
altered hepatic function (as a co-variate) on PK if (1) these patients are not excluded from
phase 2 and 3 trials and (2) there is enough PK information collected about patients to
characterize them reasonably well.  If a population PK approach is used, patients in phase
2 and 3 studies should be assessed for encephalopathy,  ascites, serum bilirubin, serum
albumin, and prothrombin time (components of the Child-Pugh score) or a similar group
of measures of hepatic function.  A population PK study should include the following
features:
  Preplanned analysis of the effect of hepatic impairment
  Appropriate evaluation of the severity of liver disease
  A sufficient number of patients and a sufficient representation of the entire range of
hepatic function to allow the study to detect PK differences large enough to warrant
dosage adjustment
  Measurement of unbound concentrations of the drug when appropriate
  Measurement of parent drug and active metabolite(s)
Such features are important if the sponsor intends to use the results to support a
conclusion that no dosage adjustment is required for patients with impaired hepatic
function.  Sponsors and applicants are referred to the FDA guidance for industry
Population Pharmacokinetics (FDA 1999) for more detailed information about the
design and execution of population PK studies, 
D. Pharmacodynamic Assessments
Pharmacodynamic assessments may be useful in studies designed to assess the effect of
altered liver function, especially if concentration-response data are not available or if
there is a concern that altered hepatic function may alter PD response.  The Agency
recommends that the selection of PD endpoints be discussed with appropriate FDA
review staff and that they be based on the pharmacologic characteristics of the drug and
its active metabolites.
V. DATA ANALYSIS
The primary intent of the data analysis is to assess the effect of hepatic impairment on the PK of
the drug and its active metabolites and, if possible, to relate a specific measure of hepatic
function or group of functions (e.g., Child-Pugh) to a relevant PK measure or parameter such as
the area under the plasma concentration curve (AUC).  From this information, dosage
recommendations for patients with impaired hepatic function can be developed.
A. Parameter Estimation
6 Contains Nonbinding Recommendations
Plasma concentration data (and urine concentration data, if collected) should be analyzed
to estimate measures or parameters describing the PK of the drug and its active
metabolite(s) (e.g., AUC, peak concentration, (C ), apparent clearance (CL/F), renal
max
and nonrenal clearance (CL  and CL ), apparent volume of distribution (Vd  or Vd ),
R NR z ss
terminal half-life (t )).  Where relevant, measures or parameters can be expressed in
1/2
terms of unbound concentrations (e.g., apparent clearance relative to the unbound drug
concentration (Clu/F=Dose/AUCu, where the subscript u indicates unbound drug)). 
Noncompartmental and/or compartmental modeling approaches to parameter estimates
can be employed.  
B. Relationship Between Measures of Hepatic Function and PK
In contrast to approaches relating measures of renal impairment to drug disposition, past
experience indicates that it has been difficult to develop a measure or group of measures
of hepatic function that predict alterations in drug PK.   Nonetheless, relationships
between hepatic functional abnormalities (e.g., hepatic blood flow, serum albumin
concentration, prothrombin time, or overall impairment scores such as Child-Pugh), and
selected pharmacokinetic parameters (e.g., total body clearance, oral clearance, apparent
volume of distribution, unbound clearance or dose-normalized area under the unbound
concentration-time curve) should be sought using linear and nonlinear models.  A
regression approach for continuous variables describing hepatic impairment and PK
parameters is appropriate, with the understanding that some correlations will rely on
categorical variables (e.g., Child-Pugh).  Typically, modeling results would include
parameter estimates of the chosen model and measures of their precision (standard errors
or confidence intervals).  Prediction error estimates are also desirable to assess
appropriateness of the model.  
C.  Development of Dosing Recommendations
The principal objective of a hepatic impairment study is to develop dosing
recommendations so that patients and practitioners can alter dose and dosing interval
appropriately in the presence of hepatic disease, again noting that subsequent careful
titration and observation are critical in this vulnerable population.  When applicable, it is
also important to point out in dosing recommendations that hepatic impairment does not
alter a drugs PK.  To reach this conclusion, a confidence interval approach, rather than a
significance test, is preferred.
A general approach in developing dosage recommendations is appropriately based on the
following considerations:
  If the effect of hepatic impairment on the PK of the drug is obvious (e.g., two-fold or
greater increase in AUC), dosage adjustments should be recommended in labeling.  It
should be noted that for prodrugs (i.e., drugs with activity predominantly due to
hepatically generated metabolite), it is possible that the dose would be increased, or
the dosing interval shortened, in hepatically impaired patients.
7 Contains Nonbinding Recommendations
  A conclusion that there is no effect (really, no clinically important effect) of hepatic
impairment on the drugs PK, would usually be supported by the establishment of one
of the following: (1) delineation of no effect boundaries, prior to the conduct of the
studies, based on information available for the investigational drug (e.g., dose- and/or
concentration-response studies), or (2) in the absence of other information to
determine a different equivalence interval, the employment of a  standard 90 percent
confidence interval of 80-125 percent for AUC and C .  FDA recognizes that
max
documentation that a PK parameter remains within an 80-125 percent no effect
boundary would be very difficult given the small numbers of subjects usually entered
into hepatic impairment studies.  If a wider boundary can be supported clinically,
however, it may be possible to conclude that there is no need for dose adjustment. 
VI. LABELING
Labeling should reflect the data pertaining to the effect of hepatic impairment on a PK and PD of
a drug (if known).  Although the many permutations of intrinsic drug characteristics and the
effect of hepatic impairment on drug performance preclude a simple specification of the labeling
for such drugs, in general drug dosage should be reduced in the relevant population (Child-Pugh)
for which significantly impaired clearance is shown.  Depending on the drugs use and
therapeutic range, and the size of the effect on clearance, the drug may be contraindicated in
severe (Child-Pugh) hepatic impairment or used with great caution.  Conversely, if the results
show no significant impairment of drug clearance in the moderate group, the drug can be
administered in mild and moderate hepatic impairment without any dose modification.  Labeling
would generally indicate caution for severe hepatic impairment if the drug has significant hepatic
clearance, and if there are no data to support a lesser labeling restriction.
If a study is not conducted for the reasons listed in Section III.B, labeling should indicate that the
impact of hepatic impairment was not studied and that effects requiring a dosage adjustment are
unlikely for the proposed drug.  More detailed recommendations for labeling statements are
provided in the following sections.
A. Clinical Pharmacology
1. Pharmacokinetics Section
Information in this section of the labeling should include:
  The mechanism of hepatic elimination (e.g., enzyme pathways, glucuronidation,
biliary excretion)
  The percent of drug that is eliminated by these mechanisms (e.g., metabolism, biliary
excretion)
  The disposition of active metabolites in patients with impaired hepatic function, if
applicable
  The effects of hepatic impairment on protein binding of parent drug and metabolites,
if applicable
8 Contains Nonbinding Recommendations
  If applicable, a description of the effects of impaired hepatic function on
stereospecific disposition of enantiomers of a racemic drug product if there is
evidence of differential stereoisomeric activity or toxicity
2. Special Populations Section
Based on studies performed in accordance with recommendations in this guidance or an
acceptable alternative, information in this section of the labeling should include:
  A brief description of the pharmacokinetic changes found in patients with hepatic
impairment
  Discussion of any issues of altered PD and dosing adjustments required for patients
with hepatic impairment
  A reference to the WARNINGS/PRECAUTIONS, CONTRAINDICATION and
DOSAGE AND ADMINISTRATION sections.
The following text provides examples of appropriate wording for this section of the
labeling.
a. If studies show no effect of altered hepatic function
The simplest situation involves drugs for which studies of impaired hepatic function have
been conducted and little or no effect on PK or PD was noted.
In a study comparing [X] patients with moderate (as indicated by
the Child-Pugh method) hepatic impairment to [X] controls, the
single/multiple dose PK/PD disposition of ________ was not
altered in patients with hepatic impairment.  No dosing adjustment
is required in patients with mild and moderate hepatic impairment.
b. If studies show an effect of altered hepatic function
For drugs in which PK or PD is influenced by hepatic impairment, the following
statement can be modified as appropriate and in accordance with what is known about the
drug (e.g., racemate with different activity of stereoisomers, active or toxic metabolite)
and from the studies performed in accordance with this guidance.
The disposition of ________ was compared in patients with
hepatic impairment and subjects with normal hepatic function.
Total body clearance of [unbound, if applicable]
_______/metabolite was reduced by ___% in patients with
moderate (as indicated by the Child-Pugh method) hepatic
impairment. The half-life of _______/metabolite is prolonged by
____ in patients with moderate hepatic impairment. Protein
binding of ________/metabolite [is/is not] affected by impaired
hepatic function. The drug/metabolite accumulates to the extent of
9 Contains Nonbinding Recommendations
____ in patients with impaired hepatic function on chronic
administration. The dosage should be reduced in patients with
mild and moderate hepatic impairment receiving _______.  
_______ should be [contraindicated/used with great caution] in
severe hepatic impairment (see WARNINGS/PRECAUTIONS,
CONTRAINDICATION and DOSAGE AND ADMINISTRATION).
c. If no studies of a population with altered hepatic function exist
In cases where no hepatically impaired patient population has been investigated, as the
basis for labeling claims, the following labeling language is recommended:
Option 1:  For no hepatic contribution to the elimination of the compound
The influence of hepatic impairment on the pharmacokinetics
of______ has not been evaluated. Because greater than 90% of the
dose is excreted in the urine as unchanged drug, hepatic
impairment would not be expected to have a significant effect on
_______elimination.
Option 2:  For limited (<20 percent) hepatic elimination
Wide Therapeutic Range
The influence of hepatic impairment on the pharmacokinetics
of_____ has not been evaluated. Because greater than 80% of the
dose is excreted in the urine as unchanged drug, hepatic
impairment would not be expected to lead to unsafe systemic
exposure of ______.
Narrow Therapeutic Range
The influence of hepatic impairment on the pharmacokinetics
of_____ has not been evaluated. Because the usual doses of the
drug are close to doses that can cause adverse effects, and there is
in-vitro or in-vivo evidence of hepatic contribution to the
elimination of_____, hepatic impairment could lead to an
increased exposure and possibly an increase in adverse effects.
Patients with impaired liver function may require reduced doses of
 ______or longer dosing intervals. If ______ is used, close
monitoring of patients with impaired liver function is important
(see WARNINGS/PRECAUTIONS, CONTRAINDICATION and
DOSAGE AND ADMINISTRATION).
Option 3:  For extensive (> 20 Percent) hepatic elimination
10 Contains Nonbinding Recommendations
Wide Therapeutic Range
The influence of hepatic impairment on the pharmacokinetics
of____ has not been evaluated. Because there is in-vitro or in-vivo
evidence of extensive hepatic contribution to the elimination of
_____, hepatic impairment would be expected to have significant
effects on the pharmacokinetics of _____. Caution should be
exercised during the use of ____ in this patient population.
Patients with impaired liver function may require reduced doses of
_____ or longer dosing intervals (see
WARNINGS/PRECAUTIONS, CONTRAINDICATION and
DOSAGE AND ADMINISTRATION).
Narrow Therapeutic Range
The influence of hepatic impairment on the pharmacokinetics
of____ has not been evaluated. Because there is in-vitro or in-vivo
evidence of extensive hepatic contribution to the elimination of
_____, hepatic impairment would be expected to have significant
effects on pharmacokinetics of _____.   ____ should be  avoided or
used with great caution in this patient population (see
WARNINGS/PRECAUTIONS, CONTRAINDICATION and
DOSAGE AND ADMINISTRATION).
Option 4:  For unknown hepatic elimination
In these circumstances, consider the compound as extensively metabolized and use the
above format.
B. Precautions/Warnings
Use in Patients with Impaired Hepatic Function: If the effects of hepatic impairment
result in clinically important changes in drug PK or PD, this information should be
included in the PRECAUTIONS section of the labeling with reference to DOSAGE AND
ADMINISTRATION.  If there is no information on the PK in patients with impaired
hepatic function, but the drug is known to have a narrow therapeutic range, a statement in
the PRECAUTIONS, WARNINGS or CONTRAINDICATIONS sections of the labeling
should be included as appropriate.
C. Dosage and Administration:
As appropriate, the following statements are recommended:
The influence of impaired hepatic function on __________
pharmacokinetics or pharmacodynamics (if known) is sufficiently
small that no dosing adjustment is required.
11 Contains Nonbinding Recommendations
For cases in which impaired hepatic function requires dosing adjustments, the appropriate
information should be included.
Special consideration should be given to combination drug products.  It is reasonable to
recommend dosing adjustment according to the degree of hepatic impairment if there is
sufficient information to indicate that the pharmacokinetics of the individual components
are similarly affected by impaired hepatic function.  In situations for which this does not
apply, the following statement should be included:
Because the doses of this fixed combination product cannot be
individually titrated and impaired hepatic function results in a
reduced clearance of component A to a much greater extent than
component B, the combination product should generally be
avoided in patients with impaired hepatic function (see
WARNINGS or PRECAUTIONS, as appropriate).  
In some cases, where various ratios of the combination product are available, it may be
possible to direct physicians to a combination with less of the hepatically cleared
component.
12 Contains Nonbinding Recommendations
REFERENCES
Carithers RL, Herlong HF, Diehl AM, Shaw EW, Combes B, Fallon H, Maddrey WC, Methyl-
prednisolone therapy in patients with severe alcoholic hepatitis, Ann Intern Med 1989;
110:685-90.
Dickson ER, Grambsch PM, Fleming TR, Fisher LD, Langworthy A, Prognosis in primary
biliary cirrhosis: model for decision making, Hepatology 1989; 10:1-7.
FDA, Policy Statement for the Development of New Stereoisomeric Drugs, May 1992.
FDA, Population Pharmacokinetics, February 1999.
Figg WD, Dukes GE, Lesesne HR, Carson SW, Songer SS, Pritchard JF, Hermann DJ, Powell
JR, and Hak LJ, Comparison of quantitative methods to assess hepatic function: Pughs
classification, indocyanine green, antipyrine, and dextromethorphan, Pharmacother
15:693-700, 1995.
Maddrey WC, Boitnott JK, Bedine MS, Weber FLJr, Mezey E, White RI, Corticosteroid therapy
of alcoholic hepatitis, Gastroenterology 1978; 75:193-9.
Pugh RNH, Murray-Lyon IM, Dawson JL, Pietroni MC, Williams R,  Transection of the
oesophagus for bleeding oesophageal varices,  Brit J Surg 1973; 60:646-9.
Tang H-S, Hu OY-P, Assessment of liver function using a novel galactose single point method, 
Digestion 1992; 52:222-31.
Testa R, Caglieris S, Risso D, et al., Monoethylglycinexylidide formation measurement as a
hepatic function test to assess severity of chronic liver disease, Am J Gastroenterol 1997;
92:2268-73.
Wiesner RH, Grambsch PM, Dickson ER, Ludwig J, MacCarty RL, Hunter EB, et al., Primary
sclerosing cholangitis: natural history, prognostic factors and survival analysis, 
Hepatology 1989; 10:430-6.
Zakim D and Boyer TD, Hepatology, A Textbook of Liver Disease, W. B. Saunders Company,
Philadelphia, 1996. 
13 Contains Nonbinding Recommendations
APPENDIX:  ASSESSMENT OF LIVER FUNCTION.
1. Child-Pugh system
Points  Scored  for  Observed  Findings
1 2 3
Encephalopathy grade* none 1 or 2 3 or 4
Ascites absent slight moderate
Serum bilirubin, mg/dL <2 2 to 3 >3
Serum albumin, g/dL >3.5 2.8 to 3.5 <2.8
Prothrombin time, sec prolonged <4 4 to 6 >6
*Grade 0: normal consciousness, personality, neurological examination, electroencephalogram
  Grade 1: restless, sleep disturbed, irritable/agitated, tremor, impaired handwriting, 5 cps waves
  Grade 2: lethargic, time-disoriented, inappropriate, asterixis, ataxia, slow triphasic waves
  Grade 3: somnolent, stuporous, place-disoriented, hyperactive reflexes, rigidity, slower waves
  Grade 4: unrousable coma, no personality/behavior, decerebrate, slow 2-3 cps delta activity
Assessment as good operative risk (A or mild) if 5 or 6 points; moderate risk (B or moderate) if 7
to 9 points; and poor operative risk (C or severe) if 10 to 15 points. (Developed for surgical
evaluation of alcoholic cirrhotics.)
2. Maddrey discriminant function (df)
df = 4.6 x (prothrombin time, in seconds) + serum total bilirubin, mg/dL
Interpretation of the df values in patients with acute alcoholic hepatitis was that the disease was
not severe if df <54, was severe if 55 to 92, and probably lethal if 93 or more and untreated.
The df was modified in a later study by Carithers, et al., (1989) to use the prolongation of
prothrombin time above normal control values and to divide the serum bilirubin by 17.1 to give
mmol/L. Patients with modified df values of 32 or more were entered into a study of
methylprednisolone treatment, corresponding to Maddrey df values of approximately 106.
3. Mayo Survival Model for Primary Biliary Cirrhosis
This model, based on Cox proportional hazards regression analyses for factors predicting death,
used the five most influential variables in a complex formula to calculate estimate survival time,
S(t), in terms of mortality risk, R:
S(t), survival probability for t years = {S (t)}exp(R-5.07), where
0
 R = 0.871 ln (B) + 2.53 ln (A) + 0.039 (Y) + 0.859 (E) + 2.38 ln (PT).
[B=bilirubin, mg/dL; A=albumin, g/dL; Y=age in years; E=edema; PT=prothrombin time, sec]
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S (t) is taken from a table of observed survivals for R =5.07, the mean value of risk score found
0
in the 418 patients observed:
  t, years 1 2 3 4 5 6 7
    S (t) 0.970 0.941 0.883 0.833 0.774 0.721 0.651
0
Later the same year, another model was developed for 174 patients with primary sclerosing
cholangitis (PSC) by Wiesner and colleagues at the same institution, but the regression analysis
identified blood hemoglobin (Hb, g/dL, below 12 g/dL), inflammatory bowel disease (IBD: 1 if
yes, 0 if no), and the histologic stage of hepatic fibrosis (S, 0 to 4) as important, in addition to
age and serum bilirubin (up to 10 mg/dL used if observed value higher):
R = 0.85 ln (B) + 0.06 (Y) - 4.39 ln (Hb) + 1.59 (IBD) + 0.51 S
4. Antipyrine
In contrast to the flow dependent indocyanine green (ICG), antipyrine has a low hepatic
extraction ratio (2 percent) (Figg et al., 1995).  It is almost completely oxidized by various
hepatic enzymes (2-hydroxylation and 1-N-demethylation) and is limited by metabolic capacity
of the intrinsic enzyme activity and not necessarily by hepatic blood flow or hepatic uptake.  It
has been used extensively as a general marker for the functional ability of the cytochrome P-450
oxidative pathway and is affected by a wide range of liver diseases (e.g., chronic liver disease,
hepatitis, and cirrhosis).  Antipyrine is effective in identifying moderate and severe hepatic
impairment, but its clearance does not change in mild liver disease.  Antipyrine clearance was
found to significantly correlate with Child-Pughs classification (r=0.67, p=0.0003).
5. Indocyanine Green (ICG)
A widely used marker of hepatic blood flow and hepatic uptake is ICG (Figg et al., 1995).  ICG
is highly extracted by the liver (70-90 percent), is not recovered in urine, is 95 percent bound to
circulating albumin, and is cleared by hepatic uptake, conjugation, and excretion into the bile. 
Hepatic blood flow as assessed by clearance of ICG is highly correlated with direct measurement
using electromagnetic flow meters.  At standard doses, its clearance follows first order kinetics. 
ICG clearance is reduced in all forms of chronic liver disease.  Elimination is particularly
impaired in alcoholic and biliary cirrhosis.  The percentage reduction found in patients with
established cirrhosis varies from 35-94 percent of that in healthy controls.  ICG clearance was
found to correlate significantly with Child-Pughs classification (r=0.86, p=0.0001).
6. Monoethylglycinexylidide (MEGX)
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This compound is the main metabolite of lidocaine, produced by oxidative N-de-ethylation by
the hepatic CYP 3A enzyme system.  It is measured at 15, 30, or 60 minutes after an intravenous
infusion over 2 minutes of 1 mg/kg of lidocaine, and correlates well with Child-Pugh scores
(Testa et al., 1997).
7. Galactose Single Point (GSP) Method
A simplification (Tang and Hu 1992) of the older, more tedious galactose elimination constant
(GEC) developed by Tygstrup in 1963 has been validated in patients with chronic hepatitis and
cirrhosis graded by the Child-Pugh scale and GEC.  The test is done by intravenously infusing
0.5 g/kg of galactose and measuring serum galactose concentration enzymatically at 60 minutes
later.  Elevated blood galactose correlates sensitively with hepatic dysfunction.  There is some
evidence that the GSP test can be used to define clearance of both highly metabolized drugs and
drugs that are hepatically excreted but not metabolized.
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