Bioavailability: objectives and types MCQs With Answer

Bioavailability: objectives and types MCQs With Answer is designed for M.Pharm students to deepen understanding of how much and how quickly an active drug reaches systemic circulation. This quiz-driven blog focuses on the objectives of bioavailability studies — such as assessing therapeutic equivalence, guiding formulation development, and informing dose adjustments — and on the various types of bioavailability (absolute, relative, apparent, and local). The questions emphasize pharmacokinetic principles (AUC, Cmax, Tmax), study design considerations, methods to enhance systemic availability, and regulatory perspectives relevant to bioequivalence. Each MCQ is crafted to test analytical reasoning and practical application, helping students prepare for exams and research in drug development and therapeutic evaluation.

Q1. Which of the following best defines absolute bioavailability (F) of an orally administered drug?

• The fraction of the administered dose that reaches the systemic circulation intact compared with an intravenous dose
• The fraction of drug excreted unchanged in urine after oral administration
• The ratio of Cmax to Tmax for an oral formulation
• The extent of drug bound to plasma proteins after oral dosing

Correct Answer: The fraction of the administered dose that reaches the systemic circulation intact compared with an intravenous dose

Q2. In a bioavailability study, which pharmacokinetic parameter is most directly used to calculate absolute bioavailability?

• AUC (area under the plasma concentration–time curve)
• Half-life (t1/2)
• Volume of distribution (Vd)
• Clearance (Cl)

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

Q3. Which study design is most commonly used in single-dose bioavailability and bioequivalence trials to minimize subject variability?

• Randomized two-period crossover design
• Parallel group design without randomization
• Open-label single-arm study
• Historical control comparison

Correct Answer: Randomized two-period crossover design

Q4. Relative bioavailability is best described as:

• Comparison of bioavailability between two non-intravenous formulations or routes
• The absolute fraction of dose absorbed after IV administration
• Bioavailability measured only in hepatically impaired subjects
• Bioavailability adjusted for protein binding

Correct Answer: Comparison of bioavailability between two non-intravenous formulations or routes

Q5. If a 100 mg oral dose gives AUC0–∞ = 40 mg·h/L and a 50 mg IV dose gives AUC0–∞ = 80 mg·h/L, what is the absolute bioavailability?

• 25%
• 50%
• 100%
• 200%

Correct Answer: 25%

Q6. Which factor most directly reduces oral bioavailability via first-pass metabolism?

• High hepatic metabolic extraction ratio
• Low plasma protein binding
• Large volume of distribution
• Slow renal excretion

Correct Answer: High hepatic metabolic extraction ratio

Q7. Which of the following is NOT an objective of conducting bioavailability or bioequivalence studies?

• To determine interchangeability of generic and reference products
• To evaluate the potential for dose adjustments in special populations
• To directly measure a drug’s mechanism of action at receptor sites
• To support regulatory approval of a new formulation

Correct Answer: To directly measure a drug’s mechanism of action at receptor sites

Q8. Which parameter indicates the rate of absorption and is often compared in BE studies besides AUC?

• Cmax
• Apparent clearance
• Apparent volume of distribution
• Fraction unbound

Correct Answer: Cmax

Q9. For drugs exhibiting enterohepatic recycling, bioavailability estimations using AUC may be affected because:

• AUC can show secondary peaks leading to overestimation of exposure
• Clearance becomes instantaneous and AUC is underestimated
• Tmax is always shorter and reduces AUC
• Protein binding is eliminated and AUC is invalid

Correct Answer: AUC can show secondary peaks leading to overestimation of exposure

Q10. Which of the following formulation strategies is commonly used to enhance oral bioavailability of a poorly water-soluble BCS class II drug?

• Use of lipid-based formulations or self-emulsifying drug delivery systems (SEDDS)
• Increasing tablet hardness
• Using enteric coating to prevent gastric absorption entirely
• Reducing the dose to minimize solubility issues

Correct Answer: Use of lipid-based formulations or self-emulsifying drug delivery systems (SEDDS)

Q11. Which statement is true about absolute bioavailability of an IV bolus administration?

• It is defined as 100% (F = 1) by convention
• It is variable and typically less than oral bioavailability
• It cannot be determined because there is no absorption
• It is calculated using Tmax and Cmax only

Correct Answer: It is defined as 100% (F = 1) by convention

Q12. When comparing two formulations, a 90% confidence interval for the ratio of geometric means of AUC and Cmax falling within 80–125% indicates:

• Regulatory bioequivalence (for most immediate-release drugs)
• That the test product is significantly superior
• That the test product is bioinequivalent and should be rejected
• That the study design is invalid and must be repeated

Correct Answer: Regulatory bioequivalence (for most immediate-release drugs)

Q13. Which sampling consideration is most critical when designing a single-dose bioavailability study to estimate AUC0–∞ accurately?

• Ensure adequate sampling into the terminal elimination phase to calculate AUC extrapolation
• Collect samples only until Cmax is measured and stop
• Obtain only pre-dose and single post-dose samples
• Use urine sampling exclusively and avoid plasma sampling

Correct Answer: Ensure adequate sampling into the terminal elimination phase to calculate AUC extrapolation

Q14. How does high plasma protein binding of a drug typically influence its apparent bioavailability measurement?

• Bioavailability (F) based on total drug AUC is not directly changed by protein binding but free concentration may be reduced
• High protein binding always increases measured bioavailability
• High protein binding invalidates all AUC determinations
• Bioavailability equals fraction unbound times dose

Correct Answer: Bioavailability (F) based on total drug AUC is not directly changed by protein binding but free concentration may be reduced

Q15. Which of the following can produce an apparent increase in oral bioavailability when co-administered with an enzyme inhibitor?

• Decreased first-pass metabolism leading to larger systemic exposure
• Increased renal clearance of the drug
• Increased gastric emptying causing lower absorption
• Enhanced protein binding decreasing free drug

Correct Answer: Decreased first-pass metabolism leading to larger systemic exposure

Q16. In calculating relative bioavailability between two oral formulations, what normalization is required if doses differ?

• Adjust AUC by dividing by the administered dose for each formulation
• Multiply AUC by molecular weight of the drug
• Use Tmax instead of AUC to avoid dose effects
• No normalization is necessary; compare raw AUCs directly

Correct Answer: Adjust AUC by dividing by the administered dose for each formulation

Q17. Which regulatory consideration is most important when selecting a reference product for a bioequivalence study?

• Use the locally marketed reference formulation with the same strength and dosage form
• Select any formulation with similar excipients regardless of market authorization
• Always use an experimental formulation as reference
• Reference selection is not required for generic approvals

Correct Answer: Use the locally marketed reference formulation with the same strength and dosage form

Q18. Which scenario most likely leads to underestimation of true bioavailability in an oral AUC-based study?

• Missing early sampling points during absorption leading to incomplete Cmax capture
• Too many samples in the terminal phase but few early samples
• Conducting the study in the fasted state when food enhances absorption
• Using a crossover design instead of parallel design

Correct Answer: Conducting the study in the fasted state when food enhances absorption

Q19. For a prodrug that is extensively converted to active metabolite presystemically, which statement about parent drug bioavailability is correct?

• Parent drug absolute bioavailability may be very low while systemic exposure to active metabolite can be high
• Parent drug bioavailability will always be high because prodrug design ensures absorption
• Active metabolite exposure is irrelevant for bioavailability assessment
• Prodrugs eliminate the need for bioequivalence studies

Correct Answer: Parent drug absolute bioavailability may be very low while systemic exposure to active metabolite can be high

Q20. Which pharmacokinetic process does NOT directly change the fraction of dose absorbed (fa) but can alter systemic exposure (AUC)?

• Changes in systemic clearance (Cl)
• Altered gastrointestinal dissolution affecting fa
• Reduced intestinal permeability decreasing fa
• Increased presystemic metabolism reducing fa

Correct Answer: Changes in systemic clearance (Cl)

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