Bioavailability and Bioequivalence Study

1. DRUG PRODUCT
PERFORMANCE
Submitted by : Vivek Bihania
M.Pharm(Pharmaceutics)
1st sem.

2. DRUG PRODUCT PERFORMANCE
 Defined as the release of the drug substance from the drug product leading to bioavailability of the drug
substance. The assessment of drug product performance is important since bioavailability is related both to
the pharmacodynamic response and to adverse events. Thus, performance tests relate the quality of a
drug product to clinical safety and efficacy.
 Bioavailability studies are drug product performance studies used to define the effect of changes in the
physicochemical properties of the drug substance, the formulation of the drug, and the manufacture
process of the drug product.
Bioequivalence Studies in New Drug Development (NDA)
Bioequivalence used to compare :-
(a) Early and late clinical trial formulations
(b) Formulations used in clinical trials and stability studies, if different
(c) Clinical trial formulations and to-be-marketed drug products, if different
(d) Product strength equivalence, as appropriate.
Bioequivalence study designs support new formulations of previously approved products, such as a new fixed-dose combination
version of two products approved for coadministration, or modified-release versions of immediate-release products
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3. Drug product performance and new drug product development for NDAs. Drug
product performance may be determined in vivo by bioequivalence studies or in
vitro by comparative drug dissolution studies. BA = bioavailability. 3

4. Drug product performance and generic drug product development. Drug product
performance may be determined in vivo by bioequivalence studies or in vitro by
comparative drug/release dissolution studies.
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5. Bioequivalence Studies in Generic Drug Development (ANDA)
 A generic drug product is a multisource drug product that has been approved by the FDA as a therapeutic
equivalent to the reference listed drug product (usually the brand or innovator drug product) and has
proven equivalent drug product performance.
 The generic drug manufacturer must demonstrate that the generic drug product is pharmaceutically
equivalent, bioequivalent, and therapeutically equivalent to the comparator brand-name drug product.
 Drug product performance comparison measured by in vivo bioequivalence studies in normal healthy adult,
comparisons in vitro may also include comparative drug dissolution/release profiles.
 generic drug manufacturer may make changes after FDA approval in the formulation, in the source of the active
pharmaceutical ingredient, manufacturing process, or other changes.
 For any postapproval change, the manufacturer must demonstrate that the change did not alter the
performance of the drug product.
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6. PURPOSE OF BIOAVAILABILITY AND BIOEQUIVALENCE STUDIES
 Bioavailability is defined as the rate and extent to which the active ingredient or active
moiety is absorbed from a drug product and becomes available at the site of action.
 Relative bioavailability studies compare two drug product formulations. A bioequivalence study is
a specialized type of relative bioavailability study.
 Bioavailability studies are drug product performance studies used to define the effect of
changes in the physicochemical properties of the drug substance, the formulation of the drug,
and manufacture process of the drug product.
 Bioavailability and bioequivalence can be considered as performance measures of the drug
product in vivo.
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7. RELATIVE AND ABSOLUTE AVAILABILITY
 A drug product’s bioavailability provides an estimate
of the relative fraction of the administered dose
that is absorbed into the systemic circulation (US-
FDA, CDER, 2014c)
 The fraction (f) involves comparing the drug
product’s systemic exposure (represented by
the concentration-versus-time or pharmacokinetic
profile) with that of a suitable reference product.
 The AUC is considered the most reliable measure
of a drug’s bioavailability, as it is directly
proportional to the total amount of unchanged
drug that reaches the systemic circulation Plasma drug concentration–time curve after oral
drug administration
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8. 1. Absolute Bioavailability
 Absolute bioavailability compares the bioavailability of the active drug in the systemic circulation following extravascular administration with the
bioavailability of the same drug following intravenous administration.
Fabs = fraction of the dose absorbed, expressed as a percentage;
AUCpo = AUC following oral administration;
Div = dose administered intravenously;
AUCiv = AUC following intravenous administration; and
Dpo = dose administered orally.
2. Relative Bioavailability
In a relative bioavailability study, the systemic exposure of a drug in a designated formulation (generally referred to as treatment A or reference
formulation) is compared with that of the same drug administered in a reference formulation (generally referred to as treatment B or test formulation).
In a relative bioavailability study, the AUCs of the two formulations are compared as follows:
Frel = relative bioavailability of treatment (formulation) A, expressed as a
percentage;
AUCA = AUC following administration of treatment (formulation) A;
DA = dose of formulation A;
AUCB = AUC of formulation B; DB is the dose of formulation B 8

9. METHODS FOR ASSESSING BIOAVAILABILITY AND BIOEQUIVALENCE
FDA’s regulations (US-FDA, CDER, 2014a) list the following approaches to determining bioequivalence, in
descending order of accuracy, sensitivity, and reproducibility.
1. In vivo measurement of active moiety or moieties in biological fluid (ie, a pharmacokinetic study)
2. In vivo pharmacodynamic (PD) comparison
3. In vivo limited clinical comparison
4. In vitro comparison
5. Any other approach deemed acceptable (by the FDA)
 The design of the bioavailability study depends on the objectives of the study, the ability to analyze
the drug (and metabolites) in biological fluids, the pharmacodynamics of the drug substance, the
route of drug administration, and the nature of the drug product.
 Systemically active drugs, bioequivalence should be demonstrated by an in vivo study based on
pharmacokinetic (PK) endpoints, as this is the most sensitive, accurate, and reproducible approach.
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10. Methods for Assessing Bioavailability and Bioequivalence
In vivo measurement of active moiety or moieties in
biological fluids
1. Plasma drug concentration
2. Time for peak plasma (blood) concentration (tmax)
3. Peak plasma drug concentration (Cmax)
4. Area under the plasma drug concentration–time curve
(AUC)
Urinary drug excretion
1. Cumulative amount of drug excreted in the urine (Du)
2. Rate of drug excretion in the urine (dDu/dt)
3. Time for maximum urinary excretion (t)
In vivo pharmacodynamic (PD) comparison
1. Maximum pharmacodynamic effect (Emax)
2. Time for maximum pharmacodynamic effect
3. Area under the pharmacodynamic effect–time curve
4. Onset time for pharmacodynamic effect
Clinical endpoint study
Limited, comparative, parallel clinical study using
predetermined clinical endpoint(s) and performed in patients
In vitro studies
1. Comparative drug dissolution, f2 similarity factor
2. In vitro binding studies
Examples: Cholestyramine resin—In vitro equilibrium and
kinetic binding studies
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11. Urinary Drug Excretion Data
 Urinary drug excretion data is an indirect method for
estimating bioavailability. The drug must be excreted in
significant quantities as unchanged drug in the urine.
 Du : The cumulative amount of drug excreted in the
urine, Du∞, is related directly to the total amount of
drug absorbed. Experimentally, urine samples are
collected periodically after administration of a drug
product. Each urine specimen is analyzed for free drug
using a specific assay.
 When the drug is almost completely eliminated (point
C), the plasma concentration approaches zero and the
maximum amount of drug excreted in the urine, Du∞ , is
obtained. Corresponding plots relating the plasma
level–time curve and the cumulative
urinary drug excretion.
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12. BIOEQUIVALENCE STUDIES BASED ON PHARMACODYNAMIC
ENDPOINTS—IN VIVO PHARMACODYNAMIC (PD) COMPARISON
The following criteria for a PD endpoint study are important:
 A dose–response relationship is demonstrated.
 The PD effect of the selected dose should be at the rising phase of the dose–response curve,
 Sufficientent measurements should be taken to assure an appropriate PD response profile.
 All PD measurement assays should be validated for specificity, accuracy, sensitivity, and precision.
1. A pharmacodynamic endpoint is an acute pharmacologic effect that is directly related to the drug’s
activity that can be measured quantitatively.
2. Bioavailability is determined by characterization of the dose–response curve. For bioequivalence
determination, pharmacodynamic parameters including the total area under the acute
pharmacodynamic effect–time curve, peak pharmacodynamic effect, and time for peak
pharmacodynamic effect.
3. The onset time and duration of the pharmacokinetic effect may also be included in the analysis of the
data. The use of pharmacodynamic endpoints for the determination of bioavailability and bioequivalence
is much more variable than the measurement of plasma or urine drug concentrations.
Acute pharmacodynamic effect–
time curve measured periodically
after a single oral dose. 12

13. BIOEQUIVALENCE STUDIES BASED ON CLINICAL ENDPOINTS—
CLINICAL ENDPOINT STUDY
 The clinical study is usually a limited, comparative, parallel clinical study using predetermined clinical
endpoint(s)
 Clinical endpoint BE studies are recommended for those products that have negligible systemic uptake, for
which there is no identified PD measure, and for which the site of action is local.
 Comparative clinical studies have been used to establish bioequiv-alence for topical antifungal drug products
IN VITRO STUDIES
 Comparative drug release/dissolution studies under certain conditions may give an indication of drug bio-
availability and bioequivalence.
 Comparative dissolution profiles may be considered similar if the similarity factor (f2) is greater than 50.
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14. DESIGN AND EVALUATION OF BIOEQUIVALENCE STUDIES
Objective :
The drug bioavailability from test and reference products is not statistically different when administered to patients or subjects at the same molar dose
from pharmaceutically equivalent drug products through the same route of administration under similar experimental conditions.
Study Considerations :
(1) The scientific questions and objectives to be answered,
(2) The nature of the reference material and the dosage form to be tested,
(3) The availability of analytical methods,
(4) The pharmacokinetics and pharmacodynamics of the drug substance,
(5) The route of drug administration, and
(6) Benefit–risk and ethical considerations with regard to testing in humans.
 The test and reference drug formulations must contain the same drug in the same dose strength and in similar dosage forms (eg, immediate
release or controlled release).
 Before beginning the study, the Institutional Review Board (IRB) of the clinical facility in which the study is to be performed must approve the
study.
 The IRB is composed of both professional and lay persons with diverse backgrounds who have clinical experience and expertise as well as
sensitivity to ethical issues and community attitudes.
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15. Reference Listed Drug (RLD)
 The FDA designates a single reference listed drug as the standard drug product to which all generic
versions must be shown to be bioequivalent.
 The reference standard is the reference listed drug (RLD), which is listed in the FDA’s Approved Drug
Products with Therapeutic Equivalence Evaluations—the Orange Book (US-FDA, CDER, 2014d), and the
proposed generic drug product is often referred to as the “test” drug product.
 in vivo bioequivalence study, the total content of the active drug substance in the test product (generally the
generic product) must be within 5% of that of the reference product.
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16. Regulatory Recommendations for Optimizing Bioavailability Study Design
 Use of a randomized crossover design whenever possible.
 Enrolling both male and female subjects whenever possible
 Administering single doses rather than multiple doses, as single-dose studies are more
sensitive, although multiple-dose studies may be more suitable in some cases
 Conducting the studies under fasting and fed conditions
 Measuring the parent drug rather than metabolites, unless the parent cannot be reliably
measured. Presystemically formed metabolites that contribute meaningfully to safety and
efficacy should also be measured.
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17. Factors Influencing Bioavailability and Impact on Drug Development
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18. Analytical Methods
 in vivo bioavailability, bioequivalence, or pharmacodynamic studies must be validated for accuracy and
sufficient sensitivity.
 The analytical method for measurement of the drug must be validated for accuracy, precision, sensitivity,
specificity, and robustness.
 The use of more than one analytical method during a bioequivalence study may not be valid, because
different methods may yield different values.
 Measurement of the active metabolite is important for very high-hepatic clearance (first-pass
metabolism) drugs when the parent drug concentrations are too low to be reliable.
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19. Study designs
 The FDA provides the guidance for the performance of: In vitro dissolution and In vivo
bioequivalence studies which include(solid oral dosage form):
1. Fasting study
2. Food intervention study
3. Sprinkle BE study (extended release capsules having beads)
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20. 1.Fasting studies
1. This study is required for all immediate release and modified release oral dosage forms
2. Both male and female subjects are included.
3. Overnight fasting is required(at least 10 hrs).
4. Afler adm. Of drug fasting is continued up to 4 more hrs.
5. Blood sampling is performed before dose and at diff intervals after dose.
6. Plasma drug conce time profile is obained.
7. No other medication given at least 1 week prior to study
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21. 2.Food intervention study
1. It uses single dose, randomized, 2 treatment, 2 period crossover study.
2. Conducted using meal conditions that have greatest effect on GI physiology
3. Meal containing high calories ( 50 % of total caloric content ) and fat ( 800-1000 cal ) is taken.
4. After a overnight fast of 10 hrs, meal is given 30min priorto dosing.
5. The meal is consumed over 30min with admn.of drug(with 240ml of water) immediately after meal.
6. No food is allowed 4hrs after dosing.
7. Study on drugs like ibuprofen and naproxen which is affected by food.
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22. 22
BE Study Designs

23. CROSSOVER STUDY DESIGNS
• Latin-square crossover designs for a bioequivalence study in human
volunteers, comparing three different drug formulations (A, B, C) or four
different drug formulations (A, B, C, D).
• The Latin-square design plans the clinical trial so that each subject
receives each drug product only once, with adequate time between
medications for the elimination of the drug from the body.
• Carryover effects from any particular drug product are minimized by
changing the sequence or order in which the drug products are given to
the subject. Thus, drug product B may be followed by drug product A, D,
or C
• After each subject receives a drug product, blood samples are collected
at appropriate time intervals so that a valid blood drug level–time curve is
obtained.
• The time intervals should be spaced so that the peak blood
concentration, the total area under the curve, and the absorption and
elimination phases of the curve may be well described.
• A two-period study is a study that is performed on two different days (time
periods) separated by a washout period during which most of the drug
is eliminated from the body—generally about 10 elimination half-lives.
• A sequence refers to the number of different orders in the treatment
groups in a study.
Latin-Square Crossover Design for a Bioequivalence
Study of Three Drug Products in Six Human Volunteers
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24. 2.Replicated Crossover Study Designs
 Replicate design studies may be used for highly
variable drugs and for narrow therapeutic index
drugs.
 In the case of highly variable drugs (%CV greater than
30), a large number of subjects (>80) would be needed
to demonstrate bioequivalence using the standard
two-way crossover design.
 Drugs with high within-subject variability generally
have a wide therapeutic window and despite high
variability, these products have been demonstrated to
be both safe and effective.
 Replicated crossover designs are used for the
determination of individual bioequivalence, to
estimate within-subject variance for both the test and
reference drug products, and to provide an
estimate of the subject-by-formulation interaction
variance
Four-period, two-sequence, two-formulation
design is shown below:
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25. 3. Scaled average bioequivalence
1. 3 sequence, 3 period, 2 treatment partially replicated crossover design.
2. This design allows the estimation of within –subject variance and subject- by formulation interaction
for reference product.
3. Completion time of This study is shorter than Fully replicated Four way Crossover.
4. If the test has lower variability than reference product,the study will need smaller no. of subjects.
5. This is evaluated for both AUC and Cmax.
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26. 4.Non replicate parallel study design
1. For the drugs having long elimination haIf life or depot injection in which the drug is slowly released over
weeks and month.
2. Two separate groups of volunteers are used product.
3. Onegroup will have the test product while the other will have the reference Product.
4. Blood sample collection time should be adequate to ensure completion of GI Transit(2-3days)
5. Cmax and AUC, 72 hrs after dose admn. Can be used to characterize peak and total drug exposure.
6. This design is not for drugs that have high intrasubject variability in distribution and clearance.
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27. 5.Multiple dose (steady state) study design
1. Multiple doses of same Drug are given consecutivly to reach steady state plasma drug levels.
2. The multiple dose study is designed as steady state, randomized, 2 treatment, 2 way crossover study comparing equal dose of test and
reference.
3. To ascertain that the subjects are at steady state, three consecutive trough concentration (Cmin) are determined.
Pharmacokinetic analyses include calculation of following parameters for each subject:
AUC0-t ➡ Area under the curve during a dosing intervals
tmax ➡ Time to Cmax during a dosing interval
Cmax ➡ Maximum drug concentration during dosing interval
Cmin ➡ Drug concentration at end of a dosing interval
Cavg ➡ The average drug concentration during a dosing interval avg
Degree of fluctuation- (Cmax-Cmin)/Cmax ; Swing-(Cmax-Cmin/Cmin
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28. Narrow Therapeutic Index Drugs
 Referred to as critical dose drugs, are drugs in which small changes in dose or concentration may lead to serious therapeutic
failures or serious adverse drug reactions in patients.
Narrow therapeutic index drugs consistently display the following characteristics:
(a) Subtherapeutic concentrations may lead to serious therapeutic failure;
(b) There is little separation between therapeutic and toxic doses (or the associated plasma concentrations);
(c) They are subject to therapeutic monitoring based on pharmacokinetic or pharmacodynamic measures;
(d) They possess low-to-moderate withinsubject variability (<30%); and
(e) In clinical practice, doses are generally adjusted in very small increments (<20%).
 Narrow therapeutic index drugs should employ a four-way, fully replicated, crossover study design.
 The FDA currently recommends that all bioequivalence studies on narrow therapeutic index drugs must pass both the reference-
scaled approach and the unscaled average bioequivalence limits of 80.00%–125.00%.
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29. Determination of Bioequivalence of Drug Products in Patients Maintained on a Therapeutic
Drug Regimen
Multiple-dose bioequivalence study in patients. Bioequivalence is determined by comparison of the steadystate plasma
drug-versus-time profile after administration of the reference drug product A to the steady-state plasma drug–time profile
after administration of the test drug product B.
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30. Statistical Analysis for Average Bioequivalence
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31. STUDY SUBMISSION AND DRUG REVIEW PROCESS
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32. Conditions That May Affect Drug Dissolution and Release
 Drug substance
 Particle size
 Polymorph
 Surface area
 Chemical stability in dissolution media
 Formulation of drug product Excipients
(lubricants, suspending agents, etc)
 Medium Volume
 pH
 Molarity
 Co-solvents, added enzymes/surfactants
 Temperature of medium
 Apparatus
 Hydrodynamics
1. Agitation rate
2. Shape of dissolution vessel
3. Placement of tablet in vessel
4. Sinkers (for floating products and products that stick to
side of vessel)
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33. THANK YOU ALL
ANY QUESTIONS?........