NAPLEX QBANK Pharmacology and Mechanism of Action 3

Question 1

Which antibiotic mechanism is associated with inhibition of the 50S ribosomal subunit?

Accepted Answer

Macrolides such as azithromycin

Answer

Macrolides bind the 50S subunit to block bacterial protein synthesis.

Question 2

Phenytoin exerts its antiseizure effect mainly by:

Accepted Answer

Blocking voltage-gated sodium channels

Answer

Phenytoin stabilizes inactivated sodium channels, reducing repetitive neuronal firing.

Question 3

Why must aminoglycosides be dosed carefully with monitoring?

Accepted Answer

Narrow therapeutic index with nephro- and ototoxicity

Answer

Aminoglycosides have a narrow therapeutic index, risking nephrotoxicity and ototoxicity.

Question 4

Which drug increases insulin secretion by closing pancreatic K-ATP channels?

Accepted Answer

Glipizide (sulfonylurea)

Answer

Sulfonylureas close beta-cell K-ATP channels, depolarizing the cell to trigger insulin release.

Question 5

The mechanism of action of digoxin includes:

Accepted Answer

Inhibition of Na+/K+ ATPase increasing intracellular calcium

Answer

Digoxin inhibits Na+/K+ ATPase, raising intracellular calcium and increasing contractility.

NAPLEX QBANK Practice Test