A 55-year-old male with chronic hypertension is prescribed valsartan. Valsartan works by:

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: 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.

Correct Answer: A

Rationale: The correct answer is A: Blocking muscarinic receptors in the lungs. Tiotropium is an anticholinergic medication that works by blocking muscarinic receptors in the lungs. By doing so, it causes bronchodilation and helps in managing asthma symptoms. The other choices are incorrect because tiotropium does not stimulate beta-2 adrenergic receptors (B), inhibit the release of histamine from mast cells (C), or directly decrease the production of mucus in the airways (D). The mechanism of action of tiotropium specifically involves blocking muscarinic receptors, making choice A the correct answer.

Correct Answer: A

Rationale: The correct answer is A: Blocking the action of angiotensin II at its receptor. Losartan is an angiotensin II receptor blocker (ARB), which binds to angiotensin II receptors, preventing angiotensin II from exerting its effects such as vasoconstriction and aldosterone release. This action results in vasodilation, decreased blood pressure, and reduced workload on the heart. Choices B, C, and D are incorrect as losartan does not inhibit the conversion of angiotensin I to angiotensin II, increase sodium excretion in the kidneys, or block calcium channels in the blood vessels.

Correct Answer: A

Rationale: The correct answer is A: Inhibiting the absorption of cholesterol in the small intestine. Ezetimibe is a medication that works by blocking the absorption of dietary cholesterol in the small intestine, leading to decreased levels of LDL cholesterol in the blood. This mechanism helps reduce overall cholesterol levels in the body. Choices B, C, and D are incorrect because ezetimibe does not inhibit HMG-CoA reductase in the liver (like statins), increase the excretion of cholesterol in the bile, or increase HDL cholesterol levels.