NAPLEX QBANK Pharmacology and Mechanism of Action 2

Question 1

A patient on warfarin starts amiodarone. What is the primary mechanism of the resulting increased INR?

Accepted Answer

Inhibition of CYP2C9 metabolism of warfarin

Answer

Amiodarone inhibits CYP2C9 (and CYP3A4), reducing warfarin metabolism and raising INR.

Question 2

Which mechanism explains why ACE inhibitors can cause a dry cough?

Accepted Answer

Accumulation of bradykinin and substance P

Answer

ACE normally degrades bradykinin, so its inhibition raises bradykinin levels, triggering cough.

Question 3

Metformin's primary glucose-lowering mechanism is best described as:

Accepted Answer

Decreasing hepatic gluconeogenesis

Answer

Metformin chiefly reduces hepatic glucose production via AMPK activation.

Question 4

Which drug class works by irreversibly inhibiting the proton pump (H+/K+ ATPase)?

Accepted Answer

Proton pump inhibitors

Answer

PPIs covalently bind and irreversibly inhibit gastric H+/K+ ATPase.

Question 5

The antiplatelet effect of clopidogrel requires which step?

Accepted Answer

CYP2C19 activation to its active metabolite

Answer

Clopidogrel is a prodrug activated mainly by CYP2C19; poor metabolizers respond less.

NAPLEX QBANK Practice Test