Which of the following benzodiazepines has the shortest duration of action?

Correct Answer: A

Rationale: The correct answer is A: Triazolam. Triazolam has a short duration of action due to its rapid onset and short half-life. It is commonly used for the treatment of insomnia. Clorazepate (B), Prazepam (C), and Clordiazepoxide (D) have longer durations of action compared to Triazolam. Clorazepate is a long-acting benzodiazepine used for anxiety disorders, Prazepam is an intermediate-acting benzodiazepine, and Clordiazepoxide is a long-acting benzodiazepine used for alcohol withdrawal and anxiety. Triazolam's rapid onset and short duration make it suitable for managing acute insomnia.

Correct Answer: C

Rationale: Step-by-step rationale: 1. 5-lipoxygenase is an enzyme involved in leukotriene synthesis. 2. Zileuton is a specific 5-lipoxygenase inhibitor. 3. Budesonide and Beclometazone are corticosteroids, not 5-lipoxygenase inhibitors. 4. Sodium cromoglycate is a mast cell stabilizer, not a 5-lipoxygenase inhibitor. Summary: Choice C (Zileuton) is the correct answer as it directly inhibits 5-lipoxygenase, which is crucial in leukotriene production. Choices A, B, and D are incorrect as they are not 5-lipoxygenase inhibitors but belong to different classes of medications.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Folic acid is essential for DNA synthesis, crucial for red blood cell formation. 2. Megaloblastic anemia is characterized by large, immature red blood cells. 3. Folic acid deficiency can lead to megaloblastic anemia. 4. Therefore, folic acid supplementation is recommended for treating megaloblastic anemia. Summary: - Choice A is correct because folic acid is recommended for treating megaloblastic anemia due to its role in red blood cell formation. - Choice B is incorrect because folic acid is indeed recommended for megaloblastic anemia treatment. - Choice C is incorrect as it implies all choices are correct, which is not the case. - Choice D is incorrect as folic acid is recommended for megaloblastic anemia treatment.

Correct Answer: D

Rationale: The correct answer is D: Quinidine. Quinidine is a Class IA antiarrhythmic drug that works by blocking sodium channels, prolonging the action potential duration, and delaying repolarization in cardiac cells. This helps in treating atrial and ventricular arrhythmias. Sotalol (A) is a Class III antiarrhythmic drug, Propranolol (B) is a beta-blocker, and Verapamil (C) is a calcium channel blocker, not Class IA antiarrhythmics.

Correct Answer: D

Rationale: The correct answer is D: Minoxidil. Minoxidil is a direct-acting vasodilator, not a central-acting antihypertensive drug. Central-acting antihypertensive drugs like Methyldopa, Clonidine, and Moxonidine work by acting on the central nervous system to reduce sympathetic outflow, thereby lowering blood pressure. Minoxidil, on the other hand, works by directly relaxing smooth muscle cells in blood vessels, leading to vasodilation and reduced blood pressure. So, Minoxidil does not belong to the category of central-acting antihypertensive drugs.