MPharm Master of Pharmacy Master of Pharmacy: Pharmacokinetics and Pharmacodynamics 2 — Questions and Answers
Question 1: A drug with a volume of distribution of 700 L in a 70 kg patient is best described as:
- Confined mostly to plasma
- Extensively distributed into tissues (Correct answer)
- Bound primarily to albumin
- Eliminated renally without distribution
Correct answer: Extensively distributed into tissues
A Vd of 700 L far exceeds total body water (~42 L), indicating extensive tissue distribution and sequestration.
Question 2: Which pharmacokinetic parameter directly determines the dosing interval needed to maintain steady-state concentrations within a therapeutic window?
- Volume of distribution
- Half-life (Correct answer)
- Bioavailability
- Protein binding fraction
Correct answer: Half-life
The elimination half-life governs how quickly drug levels decline, which directly informs appropriate dosing intervals.
Question 3: During a constant-rate IV infusion, steady-state is achieved when:
- The infusion rate equals the maximum clearance
- The rate of infusion equals the rate of elimination (Correct answer)
- Bioavailability reaches 100%
- The volume of distribution stabilizes
Correct answer: The rate of infusion equals the rate of elimination
Steady-state occurs when the rate of drug input equals the rate of drug elimination, resulting in constant plasma concentrations.
Question 4: A competitive antagonist shifts the agonist concentration-response curve:
- Downward without changing the maximum response
- To the right with a reduced maximum response
- To the right with an unchanged maximum response (Correct answer)
- To the left with an increased maximum response
Correct answer: To the right with an unchanged maximum response
Competitive antagonists shift the curve to the right (higher EC50) but the maximum effect can still be achieved with enough agonist.
Question 5: Which of the following best describes the concept of intrinsic efficacy in pharmacodynamics?
- The potency of a drug relative to a reference compound
- The ability of a drug-receptor complex to produce a biological response (Correct answer)
- The drug concentration required to occupy 50% of receptors
- The maximum response achievable by any drug at that receptor
Correct answer: The ability of a drug-receptor complex to produce a biological response
Intrinsic efficacy describes the capacity of the drug-receptor complex to activate the receptor and produce a functional response.
Question 6: Enterohepatic recirculation of a drug leads to:
- Increased first-pass metabolism
- Prolonged drug half-life and sustained plasma levels (Correct answer)
- Reduced volume of distribution
- Faster renal elimination
Correct answer: Prolonged drug half-life and sustained plasma levels
Enterohepatic recirculation returns drug from bile back into systemic circulation via intestinal reabsorption, extending its apparent half-life.
Question 7: The Hill coefficient (n) in the Hill equation greater than 1 indicates:
- Inverse agonism
- Negative cooperativity at the receptor
- Sigmoidal concentration-response with positive cooperativity (Correct answer)
- Linear dose-response kinetics
Correct answer: Sigmoidal concentration-response with positive cooperativity
A Hill coefficient >1 steepens the sigmoidal concentration-response curve, reflecting positive cooperativity or multiple binding sites.
MPharm Master of Pharmacy Master of Pharmacy: Pharmacokinetics and Pharmacodynamics 2
A drug with a volume of distribution of 700 L in a 70 kg patient is best described as: