Measurement of bioavailability MCQs With Answer

Measurement of bioavailability MCQs With Answer

Introduction: This quiz set is designed for M.Pharm students studying Biological Evaluation of Drug Therapy and focuses on measurement of bioavailability. It covers theoretical concepts, practical calculation methods, study design considerations, and analytical challenges encountered when quantifying the extent and rate of drug absorption. Questions emphasize absolute and relative bioavailability, AUC calculations, terminal-phase extrapolation, deconvolution, compartmental methods (Wagner–Nelson, Loo–Riegelman), bioequivalence criteria, sampling strategy, and the impact of clearance and first-pass metabolism. Use these MCQs to deepen understanding, practice calculations, and prepare for exams and regulatory study design discussions.

Q1. What is the correct equation for calculating absolute bioavailability (F) from plasma AUC data?

• AUCpo / AUCiv × (Dose IV / Dose PO)
• AUCiv / AUCpo × (Dose PO / Dose IV)
• AUCpo × Clearance / Dose PO
• (Cmax po / Cmax iv) × (Dose IV / Dose PO)

Correct Answer: AUCpo / AUCiv × (Dose IV / Dose PO)

Q2. Which pharmacokinetic parameter most directly represents the extent of systemic drug exposure and is used to assess bioavailability?

• Cmax (maximum plasma concentration)
• Tmax (time to Cmax)
• AUC (area under the plasma concentration–time curve)
• t1/2 (elimination half‑life)

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

Q3. In noncompartmental analysis, how is AUC0–∞ calculated from observed data?

• AUC0–last + Clast / kel
• AUC0–last − Clast × kel
• AUC0–last × kel / Clast
• AUC0–last + Cmax / tmax

Correct Answer: AUC0–last + Clast / kel

Q4. How is the terminal elimination rate constant (kel) commonly estimated from plasma concentration data?

• Slope of the log-linear terminal phase of the concentration–time curve

Correct Answer: Slope of the log-linear terminal phase of the concentration–time curve

Q5. Which expression correctly represents the fraction of drug escaping hepatic extraction (Fh) in terms of hepatic blood flow (Qh) and hepatic clearance (CLh)?

• Fh = Qh / (Qh + CLh)
• Fh = CLh / (Qh + CLh)
• Fh = 1 / (1 + Qh / CLh)
• Fh = CLh / Qh

Correct Answer: Fh = Qh / (Qh + CLh)

Q6. What distinguishes absolute bioavailability from relative bioavailability?

• Absolute bioavailability uses an IV reference; relative bioavailability compares two non‑IV formulations
• Absolute bioavailability compares two oral formulations; relative uses IV reference
• Absolute bioavailability is measured only at steady state; relative is single dose
• There is no difference; both terms are interchangeable

Correct Answer: Absolute bioavailability uses an IV reference; relative bioavailability compares two non‑IV formulations

Q7. Regulatory bioequivalence for AUC and Cmax is typically judged using which acceptance range for the 90% confidence interval of the geometric mean ratio?

• 80–125%
• 70–143%
• 90–110%
• 75–133%

Correct Answer: 80–125%

Q8. What is the primary purpose of deconvolution in bioavailability studies?

• To estimate the in vivo absorption (input) rate function from plasma concentration data
• To calculate the absolute bioavailability using urinary data
• To determine the hepatic extraction ratio from metabolite data
• To transform nonlinear kinetics into linear parameters

Correct Answer: To estimate the in vivo absorption (input) rate function from plasma concentration data

Q9. The Wagner–Nelson method is most appropriately applied to estimate fraction absorbed for which pharmacokinetic model?

• One‑compartment oral absorption models with first‑order elimination
• Two‑compartment models with extensive distribution
• Nonlinear saturable absorption only
• Zero‑order infusion models exclusively

Correct Answer: One‑compartment oral absorption models with first‑order elimination

Q10. The Loo–Riegelman approach is specifically used to estimate absorption profiles for which situation?

• Two‑compartment models following oral dosing where distribution phases are significant
• One‑compartment models with instantaneous distribution
• Drugs eliminated exclusively by renal excretion unchanged
• Topical formulations with local absorption only

Correct Answer: Two‑compartment models following oral dosing where distribution phases are significant

Q11. Which assumption is essential when applying noncompartmental methods to estimate bioavailability?

• Sufficient sampling to characterize the terminal phase and approximate linear pharmacokinetics
• Drug follows a two‑compartment model with reversible binding
• Complete absence of metabolites in plasma
• Exact knowledge of tissue distribution volumes is required

Correct Answer: Sufficient sampling to characterize the terminal phase and approximate linear pharmacokinetics

Q12. How does extensive hepatic first‑pass metabolism affect oral bioavailability?

• It reduces the fraction of the dose that reaches the systemic circulation, lowering AUC
• It increases Tmax while leaving AUC unchanged
• It increases AUC because metabolites are more persistent
• It has no effect on bioavailability if renal clearance is high

Correct Answer: It reduces the fraction of the dose that reaches the systemic circulation, lowering AUC

Q13. Which relationship correctly describes the dependence of AUC on dose, bioavailability (F), and clearance (CL)?

• AUC = Dose × F / CL
• AUC = CL / (Dose × F)
• AUC = Dose / (F × CL)
• AUC = Dose × CL / F

Correct Answer: AUC = Dose × F / CL

Q14. For accurate estimation of AUC and kel in a bioavailability study, the blood sampling schedule should include which features?

• Frequent early samples to define absorption/Cmax and multiple late samples to define the terminal log‑linear phase
• Only pre‑dose and one post‑dose sample at 24 hours
• Samples only around Cmax, since terminal phase is not required for AUC
• Uniform samples every 12 hours regardless of tmax or t1/2

Correct Answer: Frequent early samples to define absorption/Cmax and multiple late samples to define the terminal log‑linear phase

Q15. How can relative bioavailability at steady state be assessed for an orally dosed drug?

• Compare AUC over one dosing interval at steady state (AUCτ) for test and reference regimens
• Compare single‑dose Tmax values only
• Use only Cmax from the first dose to infer steady‑state behaviour
• Measure urinary excretion for a single dose without reaching steady state

Correct Answer: Compare AUC over one dosing interval at steady state (AUCτ) for test and reference regimens

Q16. Which statement best describes the effect of the absorption rate on Cmax and Tmax?

• Faster absorption typically increases Cmax and decreases (earlier) Tmax
• Faster absorption decreases Cmax and increases Tmax
• Absorption rate affects only AUC and not Cmax or Tmax
• Cmax and Tmax are determined solely by volume of distribution, not absorption rate

Correct Answer: Faster absorption typically increases Cmax and decreases (earlier) Tmax

Q17. Under what conditions is urinary excretion of unchanged drug a reliable method to estimate fraction absorbed (Fa)?

• When a significant, quantifiable fraction of the dose is excreted unchanged in urine and renal recovery is complete and measured
• When the drug is completely metabolized with no parent compound in urine
• When clearance is entirely hepatic and no renal excretion occurs
• For topical drugs where systemic absorption is negligible

Correct Answer: When a significant, quantifiable fraction of the dose is excreted unchanged in urine and renal recovery is complete and measured

Q18. Why is the lower limit of quantification (LLOQ) of the bioanalytical assay important for bioavailability estimation?

• Because values below LLOQ affect extrapolated AUC0–∞ and increase uncertainty in F estimates
• Because LLOQ determines Tmax directly
• Because LLOQ changes the drug’s clearance physiologically
• Because LLOQ is only relevant to stability testing and not PK

Correct Answer: Because values below LLOQ affect extrapolated AUC0–∞ and increase uncertainty in F estimates

Q19. How does the volume of distribution (Vd) influence the extent of bioavailability (F)?

• Vd does not change the extent of bioavailability (F); it affects plasma concentrations but not F
• Higher Vd always increases F because drug distributes into tissues
• Lower Vd leads to reduced F due to faster elimination
• Vd and F are inversely proportional and directly determine each other

Correct Answer: Vd does not change the extent of bioavailability (F); it affects plasma concentrations but not F

Q20. What advantage does population pharmacokinetic (pop‑PK) modeling offer when assessing bioavailability in clinical studies?

• It allows estimation of bioavailability and variability using sparse sampling and covariate analysis across subjects
• It eliminates the need for assay validation because models correct for error
• It replaces the requirement for crossover bioequivalence designs entirely
• It ensures bioavailability values are identical among all subjects

Correct Answer: It allows estimation of bioavailability and variability using sparse sampling and covariate analysis across subjects

Download