The choice of benzodiazepines for anxiety is based on:

Correct Answer: D

Rationale: The correct answer is D because benzodiazepines have a high therapeutic index, allowing for a wide margin of safety in dosing. Flumazenil can be used to reverse benzodiazepine overdose. Physiologic dependence can develop with long-term benzodiazepine use, indicating a potential for addiction. Therefore, all of the above factors play a role in the choice of benzodiazepines for anxiety. Choices A, B, and C individually do not encompass all the important considerations for prescribing benzodiazepines.

Correct Answer: B

Rationale: The correct answer is B: Increased myocardial demands for oxygen. Theophylline is a bronchodilator that works by relaxing the smooth muscles in the airways. This relaxation can lead to increased heart rate and contractility, causing the heart to work harder and increasing its demand for oxygen. Bradycardia (choice A) is not a common side effect of Theophylline. Depression of the respiratory center (choice C) is also not a typical side effect, as Theophylline is a respiratory stimulant. Elevation of arterial blood pressure (choice D) is not directly caused by Theophylline but can occur as a secondary effect due to increased heart rate and contractility.

Correct Answer: D

Rationale: Rationale for why the correct answer is D (Constipation): 1. Iron supplements commonly cause constipation due to their effect on the gastrointestinal tract. 2. Iron slows down bowel movements and can lead to difficulty passing stool. 3. Constipation is a recognized adverse effect of oral iron therapy in medical literature. 4. Other choices are not directly related to iron therapy - anemia is treated with iron, thrombocytopenia is a low platelet count, and headache is not a common side effect of iron supplements.

Correct Answer: A

Rationale: Correct Answer: A Rationale: A: ACE inhibitors directly inhibit the conversion of angiotensin I to angiotensin II, not angiotensinogen to angiotensin I. B: Enalapril is indeed a prodrug that is converted to an active metabolite. C: ACE inhibitors do reduce the secretion of aldosterone. D: ACE inhibitors can lead to hyperkalemia when combined with a potassium-sparing diuretic due to decreased aldosterone levels.

Correct Answer: D

Rationale: Step-by-step rationale for D (Minoxidil) as the correct answer: 1. Minoxidil is a vasodilator used for hypertension. 2. It acts by opening potassium channels in vascular smooth muscle cells. 3. Opening potassium channels leads to hyperpolarization, causing relaxation. 4. This relaxation reduces peripheral vascular resistance, decreasing blood pressure. Summary: A (Dipyridamole) is a platelet inhibitor, not a potassium channel opener. B (Validol) is a mild cardiac sedative. C (Atenolol) is a beta-blocker. The correct answer is D (Minoxidil) because it directly acts on potassium channels to induce vasodilation.