Which of the following drugs alters permeability of Candida cell membranes:

Correct Answer: C

Rationale: Nystatin, like amphotericin B, binds ergosterol in Candida cell membranes, altering permeability and causing cell death, while ketoconazole inhibits ergosterol synthesis.

Correct Answer: D

Rationale: Pyrantel is the drug of choice for nematode (roundworm) infections like ascariasis, paralyzing worms by acting on their neuromuscular junctions.

Correct Answer: A

Rationale: Zidovudine (AZT), a nucleoside reverse transcriptase inhibitor, blocks HIV reverse transcriptase, preventing viral RNA conversion to DNA.

Correct Answer: A

Rationale: Amantadine and rimantadine target influenza A’s M2 channel, and interferons have broad antiviral effects including influenza. Acyclovir is specific to herpes viruses, not influenza.

Correct Answer: D

Rationale: First-generation antihistamines (e.g., diphenhydramine) cause sedation, have anti-emetic effects, and some anti-parkinsonian effects, but cardiac arrhythmias are rare and more associated with second-generation drugs like terfenadine.