Bioavailability and bioequivalence studies MCQs With Answer

Bioavailability and bioequivalence are cornerstone concepts in clinical research and pharmaceutical development, especially for M.Pharm students preparing for regulatory studies and generic drug approvals. This set of MCQs focuses on core principles — definitions, pharmacokinetic parameters (AUC, Cmax, Tmax), study designs, statistical approaches, regulatory criteria, biowaivers, IVIVC, and special cases such as highly variable or narrow therapeutic index drugs. The questions are crafted to deepen understanding beyond definitions, emphasizing practical aspects of study conduct, interpretation of results, and regulatory expectations. Use these questions for revision, classroom discussion, or exam practice to build confidence in designing and evaluating bioavailability and bioequivalence studies.

Q1. What is the most accepted definition of bioavailability?

• Rate and extent to which a drug or active moiety is absorbed and becomes available at the site of action
• Rate and extent to which the active drug reaches systemic circulation
• Percentage of dose eliminated unchanged in urine
• Time taken to reach maximum concentration

Correct Answer: Rate and extent to which the active drug reaches systemic circulation

Q2. How is bioequivalence commonly defined in regulatory guidance?

• Two products are bioequivalent if they have identical inactive ingredients
• Absence of significant difference in the rate and extent of absorption between two medicinal products when administered at the same molar dose
• Products that produce the same color and shape are bioequivalent
• Two products are bioequivalent if they have identical dissolution profiles in a single medium

Correct Answer: Absence of significant difference in the rate and extent of absorption between two medicinal products when administered at the same molar dose

Q3. Which pharmacokinetic parameter primarily represents the extent of drug exposure?

• Tmax
• Cmax
• AUC (Area under the plasma concentration–time curve)
• T1/2

Correct Answer: AUC (Area under the plasma concentration–time curve)

Q4. Which parameter is most commonly used as an indicator of the rate of absorption?

• AUC
• Cmax
• T1/2
• Clearance

Correct Answer: Cmax

Q5. What is the standard regulatory acceptance range for the 90% confidence interval of the geometric mean ratio for AUC and Cmax in bioequivalence studies?

• 70–143%
• 80–125%
• 90–110%
• 95–105%

Correct Answer: 80–125%

Q6. Which study design is most commonly recommended for bioequivalence assessment of immediate-release oral products?

• Single-period parallel study
• Two-period, two-sequence crossover study
• Open-label uncontrolled study
• Multiple ascending dose study

Correct Answer: Two-period, two-sequence crossover study

Q7. What is the recommended minimum washout period between periods in a crossover bioequivalence study?

• At least equal to one half-life (T1/2)
• At least 5 times the elimination half-life of the drug
• 24 hours regardless of drug half-life
• At least 10 times the dosing interval

Correct Answer: At least 5 times the elimination half-life of the drug

Q8. In which situation is a parallel design preferred over crossover for bioequivalence studies?

• When intra-subject variability is extremely low
• When the drug has a very long half-life or carryover potential making washout impractical
• When the product is a simple aqueous solution
• When the sample size required is very small

Correct Answer: When the drug has a very long half-life or carryover potential making washout impractical

Q9. Which formulation type is most commonly eligible for a regulatory biowaiver based on the Biopharmaceutics Classification System (BCS)?

• BCS Class II immediate-release solid oral dosage forms
• BCS Class I immediate-release oral drugs with rapid dissolution
• Modified-release transdermal patches
• Parenteral sterile solutions

Correct Answer: BCS Class I immediate-release oral drugs with rapid dissolution

Q10. Which data transformation is routinely applied to AUC and Cmax prior to statistical analysis in BE studies?

• Square-root transformation
• Logarithmic (natural log) transformation
• No transformation; use raw data only
• Reciprocal transformation

Correct Answer: Logarithmic (natural log) transformation

Q11. Which metric quantifies intra-subject variability relevant to determining sample size and power in BE studies?

• Between-subject standard deviation
• Within-subject coefficient of variation (CVw)
• Mean residence time (MRT)
• Apparent volume of distribution (Vd/F)

Correct Answer: Within-subject coefficient of variation (CVw)

Q12. What approach is used to address bioequivalence for highly variable drugs (HVD) with large within-subject variability?

• Use nonparametric tests only
• Scaled average bioequivalence (SABE) with expanded limits based on variability
• Apply the 70–143% acceptance range
• Require only descriptive comparison of AUC

Correct Answer: Scaled average bioequivalence (SABE) with expanded limits based on variability

Q13. Which pharmacokinetic parameter describes the lag time before absorption begins?

• Tmax
• Tlag
• Ka (absorption rate constant)
• Cmax

Correct Answer: Tlag

Q14. Which level of in vitro–in vivo correlation (IVIVC) provides a point-to-point prediction of the entire plasma profile from in vitro dissolution?

• Level D
• Level B
• Level A
• Level C

Correct Answer: Level A

Q15. Which pharmacokinetic measures are generally used as surrogate endpoints in BE studies to infer therapeutic equivalence?

• Urinary excretion rate only
• AUC and Cmax
• T1/2 and volume of distribution
• In vitro dissolution time alone

Correct Answer: AUC and Cmax

Q16. What confidence interval level is conventionally used to assess bioequivalence in most regulatory guidances?

• 95% confidence interval
• 99% confidence interval
• 90% confidence interval
• 80% confidence interval

Correct Answer: 90% confidence interval

Q17. For narrow therapeutic index (NTI) drugs, regulatory agencies often require tighter bioequivalence limits. Which example reflects such tighter limits used by some agencies?

• 60–140%
• 80–125%
• 90–111% (or similar tightened range)
• 70–130%

Correct Answer: 90–111% (or similar tightened range)

Q18. When is a fed-state bioequivalence study required?

• Only when the drug is administered intravenously
• When absorption is significantly affected by food or product labeling indicates administration with food
• When the product is used in pediatrics only
• Fed studies are never required for oral solid dosage forms

Correct Answer: When absorption is significantly affected by food or product labeling indicates administration with food

Q19. In ANOVA for a crossover BE study, which finding suggests potential carryover effects?

• Non-significant period effect
• Significant sequence effect
• Low within-subject variability
• High overall mean concentration

Correct Answer: Significant sequence effect

Q20. Which factors are the primary drivers when calculating sample size for a bioequivalence study?

• Number of study centers and study budget only
• Expected ratio of test/reference, intra-subject variability, desired power, and BE limits
• Only the mean Cmax value of the reference product
• Color and shape differences between products

Correct Answer: Expected ratio of test/reference, intra-subject variability, desired power, and BE limits

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