An outbreak of influenza A has just been reported in his community and a 45 year old man is exhibiting initial symptoms of influenza A. Which agent would be the most useful to treat him?

Correct Answer: C

Rationale: The correct answer is C: Amantadine. Amantadine is an antiviral medication that is specifically effective against influenza A virus. It works by blocking the viral ion channel, preventing the virus from entering the host cell. This inhibits viral replication and helps reduce the severity and duration of symptoms. Choice A, Cidofovir, is used to treat certain DNA viruses but is not effective against influenza A. Choice B, Famciclovir, is used to treat herpes viruses, not influenza A. Choice D, Ribavirin, is an antiviral medication used for respiratory syncytial virus and hepatitis C, but not as effective against influenza A. Therefore, the most appropriate choice in this scenario is Amantadine due to its specific activity against influenza A virus.

Correct Answer: D

Rationale: The correct answer is D: Piperazine. Piperazine is a paralytic agent that causes relaxation of the muscles of the roundworm (Ascaris), allowing it to be easily expelled from the intestine. By administering piperazine via orogastric tube, the clumped roundworms causing intestinal obstruction can be relaxed, relieving the obstruction. Levamisole, Mebendazole, and Pyrantel pamoate are not effective in relaxing the muscles of the roundworms, making them incorrect choices for this specific scenario.

Correct Answer: D

Rationale: The correct answer is D because using antibiotic combinations covering both gram positive and gram negative bacteria can disrupt the balance of normal flora in the body, leading to superinfections. Gram positive and gram negative bacteria have different susceptibility patterns, so using a combination of antibiotics increases the likelihood of killing off a wider range of bacteria, including the beneficial ones. This disruption paves the way for opportunistic pathogens to overgrow and cause superinfections. Choices A, B, and C are incorrect because narrow spectrum antibiotics target specific bacteria, short courses of antibiotics reduce the risk of resistance and overgrowth, and antibiotics completely absorbed from the small intestines have minimal impact on gut flora compared to systemic antibiotics.

Correct Answer: B

Rationale: The correct answer is B: Finasteride. Finasteride is a 5α-reductase inhibitor that reduces the conversion of testosterone to dihydrotestosterone in the prostate, thereby shrinking the prostate gland and improving urinary symptoms in BPH. Leuprolide (A) is a GnRH agonist used in prostate cancer, not BPH. Flutamide (C) is an antiandrogen used in prostate cancer. Ketoconazole (D) is an antifungal drug and not indicated for BPH.

Correct Answer: B

Rationale: The correct answer is B: Orthostatic hypotension. Terazosin is an alpha-1 blocker commonly used to treat benign prostatic hypertrophy. It works by relaxing smooth muscle in the prostate and bladder neck. This relaxation can lead to vasodilation and subsequently cause a drop in blood pressure. Orthostatic hypotension is a common adverse reaction of alpha-1 blockers due to this mechanism. The other choices, A: Erectile dysfunction, C: GI distress, and D: Gynecomastia are not typically associated with terazosin use. Erectile dysfunction can actually be improved with alpha-1 blockers as they relax smooth muscle in the prostate, allowing for easier urination and potentially improved sexual function. GI distress and gynecomastia are not common side effects of terazosin.