Which medication is most commonly prescribed for the treatment of hyperthyroidism by inhibiting thyroid hormone synthesis?

Correct Answer: B

Rationale: The correct answer is B: Methimazole. Methimazole is an anti-thyroid medication that works by inhibiting the synthesis of thyroid hormones, making it a common treatment for hyperthyroidism. It blocks the enzyme responsible for thyroid hormone production. Levothyroxine (A) is used to treat hypothyroidism by providing thyroid hormone replacement. Amiodarone (C) is an anti-arrhythmic drug that can cause thyroid dysfunction but is not commonly used for hyperthyroidism treatment. Prednisone (D) is a corticosteroid and is not used to inhibit thyroid hormone synthesis.

Correct Answer: C

Rationale: The correct answer is C: Reducing inflammation in the airways. Budesonide is a corticosteroid that works by reducing inflammation in the airways, which is a key mechanism in managing asthma symptoms. Corticosteroids like budesonide inhibit the production of inflammatory mediators and suppress immune response in the airways. This helps to decrease swelling and mucus production, ultimately improving breathing in asthma patients. Choice A is incorrect because budesonide does not block leukotriene receptors. Choice B is incorrect because budesonide does not stimulate beta-2 adrenergic receptors like beta-agonists do. Choice D is incorrect because budesonide does not inhibit the release of histamine from mast cells.

Correct Answer: A

Rationale: Step 1: Amlodipine is a calcium channel blocker that inhibits calcium ion entry into smooth muscle cells. Step 2: By blocking calcium influx, amlodipine relaxes blood vessels, reducing blood pressure. Step 3: Enalapril is an ACE inhibitor, not a calcium channel blocker. Step 4: Clonidine is a centrally acting alpha-2 adrenergic agonist, not a calcium channel blocker. Step 5: Hydrochlorothiazide is a thiazide diuretic, not a calcium channel blocker.

Correct Answer: C

Rationale: The correct answer is C: Anticoagulants. Anticoagulants are specifically designed to reduce the risk of blood clot formation by inhibiting the clotting factors in the blood. Patients with atrial fibrillation are at an increased risk of developing blood clots due to irregular heartbeats, making anticoagulants the most appropriate class of drugs for this condition. ACE inhibitors (A) are used to treat high blood pressure, not specifically for preventing blood clots. Antiplatelets (B) work by preventing platelets from sticking together, but they are not as effective as anticoagulants for reducing the risk of blood clots in atrial fibrillation. Beta-blockers (D) are used to manage heart rate and blood pressure in atrial fibrillation, but they do not directly target blood clot formation.

Correct Answer: C

Rationale: The correct answer is C: Inhibiting the If current in the sinoatrial node. Ivabradine is a selective inhibitor of the If current in the sinoatrial node, which results in lowering the heart rate without affecting other parameters like contractility or blood pressure. By reducing the If current, ivabradine slows down the heart rate, making it an effective treatment for heart failure patients. Explanation of other choices: A: Increasing the heart rate - This is incorrect because ivabradine actually decreases the heart rate. B: Blocking beta-adrenergic receptors - This is incorrect as ivabradine works through a different mechanism by inhibiting the If current. D: Increasing myocardial contractility - This is incorrect because ivabradine primarily targets heart rate and does not directly affect myocardial contractility.