OSCE Pharmacology Fundamentals 3

Question 1

A competitive antagonist is given alongside an agonist. What happens to the agonist's dose-response curve?

Accepted Answer

Shifts to the right with the same maximum effect

Answer

A competitive antagonist shifts the agonist dose-response curve to the right (higher EC50) but the maximum effect is preserved if enough agonist is available.

Question 2

Which pharmacodynamic concept describes a drug that binds a receptor and produces less than the maximum possible effect even at full receptor occupancy?

Accepted Answer

Partial agonism

Answer

Partial agonists have intrinsic efficacy less than 1, so they cannot produce the full maximal response even when all receptors are occupied.

Question 3

A patient's renal function declines significantly. Which pharmacokinetic parameter is most directly affected for renally cleared drugs?

Accepted Answer

Clearance

Answer

Renal clearance is directly reduced when GFR falls, leading to drug accumulation and potentially toxicity.

Question 4

Which term describes the minimum concentration of drug needed at the receptor to produce a measurable effect?

Accepted Answer

Threshold concentration

Answer

Threshold concentration is the minimum drug concentration required to elicit a detectable pharmacological response.

Question 5

A patient on a stable dose of theophylline starts smoking. What adjustment is expected?

Accepted Answer

Dose increase because smoking induces CYP1A2 and lowers theophylline levels

Answer

Smoking induces CYP1A2, accelerating theophylline metabolism and reducing its plasma concentration, requiring a higher dose.

OSCE Practice Test

OSCE Practice Test

OSCE Pharmacology Fundamentals 3