A 50-year-old male with hypertension is prescribed nifedipine. Nifedipine works by:

Correct Answer: A

Rationale: The correct answer is A: Blocking calcium channels in the blood vessels. Nifedipine is a calcium channel blocker that works by inhibiting the influx of calcium ions into vascular smooth muscle cells, leading to vasodilation and decreased peripheral resistance. This reduces blood pressure in hypertensive patients. Choice B (Stimulating beta-1 adrenergic receptors) is incorrect because nifedipine does not act on adrenergic receptors. Choice C (Blocking the action of angiotensin II) is incorrect as nifedipine does not target the renin-angiotensin system. Choice D (Inhibiting aldosterone secretion from the adrenal glands) is incorrect as nifedipine does not directly affect aldosterone production.

Correct Answer: B

Rationale: Amiodarone is the correct answer as it is a potent antiarrhythmic medication that works by inhibiting potassium channels, prolonging action potential duration. This helps in controlling various types of arrhythmias effectively. Lidocaine (A) works by blocking sodium channels, not potassium channels. Atenolol (C) is a beta-blocker that affects adrenergic receptors, not potassium channels. Verapamil (D) is a calcium channel blocker, which does not target potassium channels. Therefore, B is the correct choice for treating arrhythmias by inhibiting potassium channels.

Correct Answer: A

Rationale: The correct answer is A: Blocking the action of angiotensin II at its receptor. Valsartan is an angiotensin II receptor blocker (ARB) that works by binding to angiotensin II receptors, preventing angiotensin II from exerting its vasoconstrictive and aldosterone-stimulating effects. By blocking angiotensin II, valsartan helps dilate blood vessels, reduce blood pressure, and decrease the workload on the heart. Choices B, C, and D are incorrect because valsartan does not inhibit the conversion of angiotensin I to angiotensin II (choice B), inhibit aldosterone release (choice C), or directly increase sodium excretion in the kidneys (choice D).

Correct Answer: B

Rationale: The correct answer is B: Gastrointestinal bleeding. NSAIDs can irritate the lining of the stomach and intestines, leading to ulcers or bleeding. This is a well-documented and common side effect of NSAIDs due to their mechanism of action. Hypertension (A), hypoglycemia (C), and weight gain (D) are not typically associated with NSAIDs. Hypertension is more commonly linked to other types of medications, hypoglycemia is not a known side effect of NSAIDs, and weight gain is not a common side effect either.

Correct Answer: B

Rationale: The correct answer is B: Hypokalemia. Thiazide diuretics increase potassium excretion, leading to low potassium levels (hypokalemia). Thiazides inhibit sodium and chloride reabsorption in the distal tubule, causing diuresis and potassium loss. Hyperkalemia (A) is not a primary side effect of thiazides; weight gain (C) is uncommon with thiazides; hyperglycemia (D) is more associated with other classes of diuretics. In summary, hypokalemia is the primary side effect of thiazide diuretics due to increased potassium excretion.