All of the following drugs demonstrate a prolonged effect, EXCEPT:

Correct Answer: A

Rationale: The correct answer is A: Penicillin G. This is because Penicillin G has a shorter duration of action compared to the other choices. B, C, and D are all forms of long-acting penicillin preparations designed for sustained release over an extended period. Penicillin G, on the other hand, is a short-acting formulation that requires more frequent dosing due to its rapid elimination from the body. Therefore, Penicillin G does not demonstrate a prolonged effect like the other options.

Correct Answer: D

Rationale: The correct answer is D: Acyclovir. Acyclovir is a nucleoside analogue that inhibits viral DNA synthesis by acting as a chain terminator when incorporated into the viral DNA. Interferon (A) boosts the immune response, Saquinavir (B) inhibits HIV protease, and Amantadine (C) blocks viral entry. Therefore, only Acyclovir directly targets viral DNA synthesis.

Correct Answer: D

Rationale: The correct answer is D (Drug S) because it is a loop diuretic, which acts on the ascending loop of Henle to inhibit sodium and chloride reabsorption, leading to a significant increase in diuresis. Loop diuretics are the most potent diuretics among the options provided. Drug P (Choice A) is a thiazide diuretic that acts on the distal convoluted tubule and is less potent than loop diuretics. Drug Q (Choice B) is a potassium-sparing diuretic that acts on the collecting ducts and is weaker in terms of diuretic effect compared to loop diuretics. Drug R (Choice C) is an aldosterone antagonist that acts on the distal tubules and collecting ducts, but it is less potent compared to loop diuretics in increasing diuresis.

Correct Answer: A

Rationale: The correct answer is A: Isosorbide mononitrate and nifedipine. Isosorbide mononitrate dilates coronary arteries, reducing myocardial oxygen demand. Nifedipine is a calcium channel blocker that helps reduce cardiac workload. Together, they can help manage symptoms of hypertrophic cardiomyopathy. Choice B (Nitroglycerin and captopril) is incorrect because captopril is an ACE inhibitor used for heart failure, not hypertrophic cardiomyopathy. Choice C (Nitroglycerin and verapamil) is incorrect because verapamil can worsen symptoms due to its negative inotropic effects. Choice D (Verapamil and metoprolol) is incorrect because metoprolol is a beta-blocker, which can worsen symptoms in hypertrophic cardiomyopathy by reducing heart rate and contractility.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.