COMLEX-USA Pharmacology

Question 1

Which beta-blocker is cardioselective (beta-1 selective) and commonly used in heart failure?

Accepted Answer

Metoprolol succinate

Answer

Metoprolol succinate (extended-release) is a beta-1 selective blocker proven to reduce mortality in heart failure with reduced ejection fraction.

Question 2

The mechanism of action of metformin in type 2 diabetes primarily involves:

Accepted Answer

Activating AMPK to reduce hepatic gluconeogenesis

Answer

Metformin activates AMPK, which decreases hepatic gluconeogenesis and increases peripheral insulin sensitivity without causing hypoglycemia.

Question 3

A patient taking warfarin is started on trimethoprim-sulfamethoxazole for a UTI. Which effect is expected?

Accepted Answer

Increased anticoagulation due to CYP2C9 inhibition

Answer

TMP-SMX inhibits CYP2C9, which metabolizes S-warfarin, leading to increased warfarin levels and elevated INR/bleeding risk.

Question 4

Which opioid analgesic is contraindicated in patients with renal failure due to accumulation of its active metabolite morphine-6-glucuronide?

Accepted Answer

Morphine

Answer

Morphine's active metabolite morphine-6-glucuronide (M6G) accumulates in renal failure, causing prolonged sedation and respiratory depression.

Question 5

Atropine reverses bradycardia caused by organophosphate poisoning by which mechanism?

Accepted Answer

Competitively blocking muscarinic receptors

Answer

Atropine competitively antagonizes muscarinic acetylcholine receptors, reversing the excess cholinergic (SLUDGE) effects of organophosphate poisoning.

COMLEX-USA Practice Test

COMLEX-USA Practice Test

COMLEX-USA Pharmacology