NAPLEX QBANK Pharmacology and Mechanism of Action 4

Question 1

Which mechanism explains the antiemetic action of ondansetron?

Accepted Answer

5-HT3 serotonin receptor antagonism

Answer

Ondansetron blocks 5-HT3 receptors in the gut and CTZ to prevent nausea.

Question 2

Heparin produces anticoagulation primarily by:

Accepted Answer

Enhancing antithrombin III activity

Answer

Unfractionated heparin potentiates antithrombin III, which inactivates thrombin and factor Xa.

Question 3

Which mechanism describes the action of allopurinol in gout?

Accepted Answer

Inhibition of xanthine oxidase reducing uric acid production

Answer

Allopurinol inhibits xanthine oxidase, lowering uric acid synthesis.

Question 4

Nondihydropyridine calcium channel blockers (e.g., diltiazem) differ from dihydropyridines by:

Accepted Answer

Greater effect on cardiac conduction and rate

Answer

Nondihydropyridines act more on cardiac nodal tissue, slowing AV conduction and heart rate.

Question 5

The mechanism of action of bisphosphonates (e.g., alendronate) is:

Accepted Answer

Inhibition of osteoclast-mediated bone resorption

Answer

Bisphosphonates inhibit osteoclast activity and induce their apoptosis, reducing bone resorption.

NAPLEX QBANK Practice Test