Which of the following medications is used to treat arrhythmias by inhibiting potassium channels?

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: 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.

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.