OSCE Pharmacology Fundamentals 2

Question 1

A patient is prescribed warfarin. Which enzyme system is primarily responsible for its metabolism?

Accepted Answer

CYP2C9

Answer

Warfarin is primarily metabolized by CYP2C9, making it susceptible to interactions with CYP2C9 inhibitors or inducers.

Question 2

A drug has a therapeutic index of 2. Which statement best describes this drug?

Accepted Answer

It has a narrow safety margin between therapeutic and toxic doses

Answer

A therapeutic index of 2 means the toxic dose is only twice the effective dose, indicating a narrow safety margin requiring close monitoring.

Question 3

Which pharmacokinetic parameter describes the fraction of an administered dose that reaches systemic circulation unchanged?

Accepted Answer

Bioavailability

Answer

Bioavailability (F) is the fraction of administered drug that reaches systemic circulation in its active form.

Question 4

A patient taking phenytoin starts rifampicin. The nurse should anticipate which change?

Accepted Answer

Reduced phenytoin levels due to enzyme induction

Answer

Rifampicin is a potent CYP enzyme inducer that accelerates phenytoin metabolism, lowering its plasma levels.

Question 5

Which receptor type uses a G-protein coupled mechanism to mediate its intracellular effects?

Accepted Answer

Beta-adrenergic receptor

Answer

Beta-adrenergic receptors couple to Gs proteins, activating adenylyl cyclase and increasing intracellular cAMP.

OSCE Practice Test