Pharmacokinetic Models – One/Multi Compartment MCQs With Answer

Pharmacokinetic Models – One/Multi Compartment MCQs With Answer

This quiz collection focuses on one- and multi-compartment pharmacokinetic models essential for M.Pharm students studying Advanced Biopharmaceutics & Pharmacokinetics (MIP 201T). The questions cover core concepts such as model assumptions, distribution and elimination kinetics, volume of distribution, clearance, bi-exponential plasma decline, micro- and macro-rate constants, infusion and bolus dosing, and interpretation of kinetic plots. Designed to deepen understanding beyond definitions, these MCQs challenge students to apply equations, identify correct modeling approaches, and distinguish physiological and mathematical implications of compartmental analysis—preparing you for examinations and research in drug disposition modeling.

Q1. Which model assumes instantaneous and uniform distribution of drug throughout a single kinetically homogeneous space immediately after administration?

• Two-compartment open model
• One-compartment open model
• Mammillary multi-compartment model
• Non-compartmental model

Correct Answer: One-compartment open model

Q2. In a one-compartment IV bolus model with first-order elimination, the plasma concentration-time profile plotted on a semi-logarithmic graph is characterized by:

• A straight line declining monoexponentially
• A biexponential decline with distinct alpha and beta phases
• A curvilinear zero-order segment followed by exponential decline
• A constant plateau until the drug is abruptly eliminated

Correct Answer: A straight line declining monoexponentially

Q3. For an IV bolus one-compartment model, the elimination half-life (t1/2) is related to the elimination rate constant (k) by which expression?

• t1/2 = 0.693 / k
• t1/2 = k / 0.693
• t1/2 = Vd / Cl
• t1/2 = Cl / Vd

Correct Answer: t1/2 = 0.693 / k

Q4. In compartmental analysis, the volume of distribution (Vd) is best described as:

• The actual anatomical volume where the drug is physically located
• The proportionality factor between plasma concentration and amount of drug in body
• The rate at which drug is metabolized by the liver
• The volume of central compartment only when a two-compartment model is used

Correct Answer: The proportionality factor between plasma concentration and amount of drug in body

Q5. In a two-compartment IV bolus model, which phase corresponds mainly to distribution from central to peripheral compartment?

• Terminal beta phase
• Absorption phase
• Alpha distribution phase
• Elimination plateau phase

Correct Answer: Alpha distribution phase

Q6. The mammillary model in multi-compartment kinetics assumes:

• Interconnections among peripheral compartments but no central compartment
• Each peripheral compartment exchanges only with the central compartment, not with each other
• Instantaneous equilibration between all compartments
• A closed body where elimination occurs from peripheral compartments only

Correct Answer: Each peripheral compartment exchanges only with the central compartment, not with each other

Q7. Which parameter remains constant and independent of the route of administration for linear pharmacokinetics?

• Maximum concentration (Cmax)
• Volume of distribution (Vd)
• Time to peak concentration (Tmax)
• Area under the curve (AUC)

Correct Answer: Volume of distribution (Vd)

Q8. In a two-compartment model, the macro-rate constants alpha and beta are related to micro-rate constants (k12, k21, k10) how?

• Alpha and beta are simply k12 and k21 respectively
• Alpha and beta are the eigenvalues obtained from solving the characteristic equation formed by micro-rate constants
• Alpha equals k10 and beta equals sum of k12 and k21
• Macro-constants are unrelated and derived only empirically without linkage to micro-constants

Correct Answer: Alpha and beta are the eigenvalues obtained from solving the characteristic equation formed by micro-rate constants

Q9. Which experimental approach is used to estimate V1 (volume of central compartment) in a two-compartment model?

• Calculating Vd from steady-state oral dosing only
• Back-extrapolation of the plasma concentration-time curve to t = 0 for the distribution phase intercept
• Using only elimination half-life without considering distribution
• Measuring tissue concentrations exclusively

Correct Answer: Back-extrapolation of the plasma concentration-time curve to t = 0 for the distribution phase intercept

Q10. Flip-flop kinetics refers to which situation in compartmental modeling?

• The elimination rate being much faster than absorption rate, making absorption the rate-limiting step
• The distribution being instantaneous and unmeasurable
• The presence of multiple elimination pathways operating simultaneously
• Drug demonstrating linear kinetics at low doses and non-linear at high doses

Correct Answer: The elimination rate being much faster than absorption rate, making absorption the rate-limiting step

Q11. Clearance (Cl) is best defined as:

• The volume of plasma from which drug is completely removed per unit time
• The fraction of drug eliminated per hour
• The total amount of drug eliminated per unit time irrespective of concentration
• The mathematical inverse of volume of distribution

Correct Answer: The volume of plasma from which drug is completely removed per unit time

Q12. During a constant rate IV infusion in a one-compartment model with first-order elimination, steady state is achieved when:

• Infusion rate equals zero
• Rate of drug input equals rate of drug elimination
• Volume of distribution becomes infinite
• Plasma concentration begins to decline exponentially

Correct Answer: Rate of drug input equals rate of drug elimination

Q13. In a two-compartment model, which observation suggests the peripheral compartment has slow exchange with the central compartment?

• Monoexponential decline on semi-log plot
• A pronounced and prolonged terminal slope (long beta half-life)
• Immediate disappearance of distribution phase
• Equal area under distribution and elimination phases

Correct Answer: A pronounced and prolonged terminal slope (long beta half-life)

Q14. Which is true about non-compartmental analysis (NCA) compared to compartmental models?

• NCA requires specification of the number of compartments
• NCA uses model-independent parameters like AUC and MRT without assuming compartments
• NCA is superior for predicting concentration-time profiles under all dosing regimens
• NCA estimates micro-rate constants directly from exponential terms

Correct Answer: NCA uses model-independent parameters like AUC and MRT without assuming compartments

Q15. If the plasma concentration after IV bolus fits C = A e^{-alpha t} + B e^{-beta t}, what does A and B represent?

• They are the elimination half-lives
• They are intercepts representing extrapolated concentrations of each exponential component at t = 0
• They are micro-rate constants k12 and k21 respectively
• They are the volumes of central and peripheral compartments

Correct Answer: They are intercepts representing extrapolated concentrations of each exponential component at t = 0

Q16. Which statement describes an open compartmental model?

• Drug circulates but no elimination occurs from the system
• Drug can be eliminated from the system (e.g., via metabolism or excretion)
• All compartments are closed and isolated with no transfer between them
• It is exclusively used for oral dosing kinetics

Correct Answer: Drug can be eliminated from the system (e.g., via metabolism or excretion)

Q17. The mean residence time (MRT) in a one-compartment IV bolus model is equal to:

• Vd / Cl
• Cl / Vd
• 0.693 / k
• Vd × Cl

Correct Answer: Vd / Cl

Q18. Which experimental artefact can falsely create a biexponential decline and be mistaken for a two-compartment model?

• Sampling too frequently during distribution phase
• Using an insensitive assay that fails to quantify low concentrations accurately
• Intrinsic linear elimination kinetics
• Perfect mixing in the central compartment

Correct Answer: Using an insensitive assay that fails to quantify low concentrations accurately

Q19. When estimating clearance from oral dosing, which equation relates clearance to bioavailability (F) and AUC?

• Cl = (Dose × F) / AUC
• Cl = (Dose) / (AUC × F)
• Cl = AUC / (Dose × F)
• Cl = Vd / (AUC × F)

Correct Answer: Cl = (Dose) / (AUC × F)

Q20. In multi-compartment models, identifiability of micro-rate constants from plasma data alone is often limited because:

• The micro-rate constants change with sampling interval
• Plasma data provide only summed exponential terms (macro-constants), so multiple micro-parameter sets may produce identical plasma curves
• Micro-rate constants are irrelevant for drug dosing
• Peripheral tissues eliminate the drug faster than plasma

Correct Answer: Plasma data provide only summed exponential terms (macro-constants), so multiple micro-parameter sets may produce identical plasma curves

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