A patient develops antibiotic-associated pseudomembranous colitis (AAPMC) in response to drug therapy. Which of the following was the most likely cause of this severe problem?

Correct Answer: C

Rationale: Clindamycin is a common cause of C. difficile-associated pseudomembranous colitis.

Correct Answer: C

Rationale: Oxacillin is effective against beta-lactamase-producing staphylococci.

Correct Answer: D

Rationale: Acute iron toxicity is managed with gastric lavage using bicarbonate to bind iron, reducing absorption. Hydroxocobalamin is not preferred for absorption speed but for cyanide poisoning; ferrous iron is better absorbed; ascorbic acid enhances iron absorption; dialysis patients often need folic acid.

Correct Answer: D

Rationale: Rivaroxaban has a rapid onset, no INR monitoring, fewer CYP450 interactions, and a shorter duration (half-life ~5-9 hours) than warfarin, but it is not safe in severe renal impairment due to renal excretion, requiring dose adjustment.

Correct Answer: B

Rationale: Cilostazol inhibits phosphodiesterase III, increasing cAMP (not breaking it down), leading to vasodilation and antiplatelet effects. It’s used for intermittent claudication, and headache is a common side effect.