A 65-year-old female with chronic asthma is prescribed budesonide. Budesonide works primarily by:

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: 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.

Correct Answer: B

Rationale: The correct answer is B because salbutamol is a beta-2 adrenergic receptor agonist, which leads to bronchodilation by relaxing bronchial smooth muscle. This mechanism helps to relieve bronchoconstriction in asthma. Option A is incorrect as leukotriene receptors are not targeted by salbutamol. Option C is incorrect because salbutamol does not inhibit histamine release. Option D is incorrect as salbutamol does not increase mucus production; in fact, it may help reduce mucus secretion by improving airflow.

Correct Answer: A

Rationale: The correct answer is A: Blocking histamine receptors in the brain. Hydroxyzine is a first-generation antihistamine that exerts its effects by blocking histamine receptors, leading to its antihistaminic, sedative, and anxiolytic properties. The other choices (B, C, and D) are incorrect because hydroxyzine does not primarily affect serotonin levels, acetylcholine receptors, or opioid receptors in the brain. Serotonin reuptake inhibitors, anticholinergics, and opioids work through different mechanisms compared to hydroxyzine.