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: In this question, the correct answer is B) Metoprolol. Metoprolol is a beta-blocker that is useful in angina by reducing the heart rate and blood pressure, thus decreasing the workload of the heart. It does not possess vasodilator properties but works by improving the oxygen supply-demand balance of the heart. Option A) Isosorbide dinitrate and option D) Nitroglycerin are both vasodilators commonly used in angina to dilate blood vessels, reduce the workload on the heart, and improve blood flow to the heart muscle. Option C) Nifedipine is a calcium channel blocker that also works by dilating blood vessels and reducing the workload on the heart. In an educational context, understanding the mechanisms of action of different cardiovascular medications is crucial for healthcare professionals to make informed decisions in patient care. Knowing which drugs have vasodilator properties and which do not is essential in selecting the most appropriate treatment for patients with angina. This knowledge helps in optimizing therapy, managing drug interactions, and preventing potential adverse effects.