Introduction
This quiz set focuses on one-compartment IV bolus models — a foundational topic in Advanced Biopharmaceutics & Pharmacokinetics for M.Pharm students. You will find concise questions that reinforce core concepts: instantaneous mixing, the monoexponential decline of plasma concentration, mathematical relationships (C = C0 e-kt, t1/2, Vd, CL, AUC), graphical estimation methods, and practical calculations used in drug development and dose design. The questions range from conceptual to calculation-based and emphasize interpretation of semi-log plots, parameter estimation, and implications for dosing. Use these MCQs to test and deepen your understanding of single-compartment IV bolus kinetics and common analytical approaches.
Q1. What is the basic assumption of a one-compartment IV bolus model?
- The body is a single homogeneous compartment where the drug instantaneously mixes after IV bolus administration
- The drug distributes into multiple tissues with different rate constants
- The absorption process is the rate-limiting step
- Elimination occurs only from peripheral tissues, not plasma
Correct Answer: The body is a single homogeneous compartment where the drug instantaneously mixes after IV bolus administration
Q2. Which equation correctly describes plasma concentration versus time in a one-compartment IV bolus model with first-order elimination?
- C = C0 × t-k
- C = C0 e-kt
- C = (Dose/Vd) × (1 – e-kt)
- C = C0 / (1 + kt)
Correct Answer: C = C0 e-kt
Q3. Which relationship correctly links clearance (CL), elimination rate constant (k) and volume of distribution (Vd) in a one-compartment model?
- CL = k / Vd
- Vd = CL / k
- CL = k × Vd
- k = CL + Vd
Correct Answer: CL = k × Vd
Q4. What is the formula for elimination half-life (t1/2) under first-order kinetics?
- t1/2 = 0.693 / k
- t1/2 = k / 0.693
- t1/2 = ln(k) / 2
- t1/2 = Dose / CL
Correct Answer: t1/2 = 0.693 / k
Q5. For an IV bolus dose, the apparent volume of distribution (Vd) is estimated by which expression?
- Vd = CL / k
- Vd = Dose / C0
- Vd = AUC × CL
- Vd = C0 / Dose
Correct Answer: Vd = Dose / C0
Q6. The total area under the plasma concentration-time curve from time zero to infinity (AUC0-∞) after an IV bolus is given by which formula?
- AUC0-∞ = C0 / k
- AUC0-∞ = Dose / CL
- AUC0-∞ = Vd / k
- AUC0-∞ = Dose × Vd
Correct Answer: AUC0-∞ = Dose / CL
Q7. What is the recommended practical method to determine the initial concentration C0 from sampled plasma data after an IV bolus?
- Take the concentration at the earliest sample time and use it as C0
- Perform linear regression on semi-log (lnC vs time) data and extrapolate the best-fit line to time zero
- Use the mean of measured concentrations at all times
- Calculate C0 as Dose / AUC
Correct Answer: Perform linear regression on semi-log (lnC vs time) data and extrapolate the best-fit line to time zero
Q8. What are the appropriate units for clearance (CL)?
- Mass (e.g., mg)
- Concentration (e.g., mg/L)
- Volume per time (e.g., L/h or mL/min)
- Time (e.g., h or min)
Correct Answer: Volume per time (e.g., L/h or mL/min)
Q9. In a one-compartment IV bolus model, mean residence time (MRT) equals which value?
- MRT = Vd / CL
- MRT = 1 / k
- MRT = t1/2 / 2
- MRT = Dose / AUC
Correct Answer: MRT = 1 / k
Q10. For a true one-compartment model, how does steady-state volume of distribution (Vss) compare with apparent Vd after IV bolus?
- Vss is always larger than Vd
- Vss equals Vd (apparent volume of distribution)
- Vss is unrelated to Vd and cannot be compared
- Vss is half of Vd
Correct Answer: Vss equals Vd (apparent volume of distribution)
Q11. Which experimental approach yields the elimination rate constant k from plasma data?
- Nonlinear regression of concentration versus log(time)
- Linear regression of ln(concentration) versus time (slope = -k)
- Area under the curve divided by dose
- Calculating the mean of concentrations over time
Correct Answer: Linear regression of ln(concentration) versus time (slope = -k)
Q12. How does increased plasma protein binding generally affect the apparent volume of distribution (Vd) for a drug?
- Increased plasma protein binding increases Vd by promoting tissue uptake
- Increased plasma protein binding decreases Vd by retaining drug in plasma
- Protein binding has no effect on Vd
- Increased protein binding always doubles Vd
Correct Answer: Increased plasma protein binding decreases Vd by retaining drug in plasma
Q13. What is the absolute bioavailability (F) for an IV bolus dose?
- 0% (F = 0)
- 50% (F = 0.5)
- 100% (F = 1)
- Cannot be determined for IV dosing
Correct Answer: 100% (F = 1)
Q14. How is AUC0-∞ commonly calculated from observed data when the last measurable concentration is Clast?
- AUC0-∞ = AUC0-tlast – (Clast / k)
- AUC0-∞ = AUC0-tlast + (Clast / k)
- AUC0-∞ = AUC0-tlast × (Clast × k)
- AUC0-∞ = Clast / AUMC
Correct Answer: AUC0-∞ = AUC0-tlast + (Clast / k)
Q15. Which statement best describes first-order elimination kinetics?
- The rate of elimination is constant regardless of concentration
- The amount eliminated per unit time is proportional to the drug concentration
- Elimination follows zero-order kinetics only at low concentrations
- Elimination is independent of clearance
Correct Answer: The amount eliminated per unit time is proportional to the drug concentration
Q16. For multiple IV bolus dosing at fixed interval τ in a one-compartment model, which expression gives the accumulation factor R for peak concentration at steady state?
- R = 1 – e-kτ
- R = 1 / (1 – e-kτ)
- R = e-kτ / (1 – e-kτ)
- R = k × τ
Correct Answer: R = 1 / (1 – e-kτ)
Q17. On a semi-log plot of concentration versus time, what does the slope of the terminal phase represent?
- The slope equals +k
- The slope equals -k
- The slope equals CL / Vd
- The slope equals AUC
Correct Answer: The slope equals -k
Q18. If clearance (CL) doubles for a drug given as a fixed IV bolus dose, what happens to AUC0-∞ (all else equal)?
- AUC doubles
- AUC remains unchanged
- AUC is halved
- AUC increases by a factor of four
Correct Answer: AUC is halved
Q19. Given Vd = 50 L and k = 0.1 h-1 for a one-compartment IV bolus drug, what is the clearance (CL)?
- 0.2 L/h
- 5 L/h
- 500 L/h
- 0.005 L/h
Correct Answer: 5 L/h
Q20. In linear (dose-proportional) pharmacokinetics for a one-compartment IV bolus drug, which parameter is directly proportional to dose (i.e., dose-dependent)?
- Elimination half-life (t1/2)
- Clearance (CL)
- Area under the curve (AUC)
- Elimination rate constant (k)
Correct Answer: Area under the curve (AUC)
