A 60-year-old female with chronic heart failure is prescribed hydralazine. Hydralazine works by:

Correct Answer: A

Rationale: The correct answer is A because hydralazine works by relaxing vascular smooth muscle through a direct vasodilatory effect, leading to decreased systemic vascular resistance and afterload. This relaxation occurs by increasing nitric oxide production, which promotes vasodilation. This mechanism helps reduce the workload on the heart and improve cardiac output in patients with heart failure. Choice B is incorrect because hydralazine does not block beta-1 adrenergic receptors in the heart. Choice C is incorrect because hydralazine does not directly affect sodium excretion in the kidneys. Choice D is incorrect because hydralazine does not inhibit the conversion of angiotensin I to angiotensin II; that is the mechanism of action for ACE inhibitors.

Correct Answer: A

Rationale: The correct answer is A: Phenytoin. Phenytoin is a sodium channel blocker that stabilizes the neuronal membrane by inhibiting repetitive firing of action potentials. This mechanism helps control seizures. Clonazepam (B) acts on GABA receptors, Valproate (C) increases GABA levels, and Gabapentin (D) modulates calcium channels - all different mechanisms not related to stabilizing neuronal membranes for seizure control.

Correct Answer: A

Rationale: The correct answer is A: Inhibiting osteoclast-mediated bone resorption. Raloxifene is a selective estrogen receptor modulator (SERM) that works by binding to estrogen receptors in bone tissue, inhibiting osteoclast activity, and reducing bone resorption. This helps to maintain bone density in patients with osteoporosis. Choices B and C are incorrect as raloxifene does not directly promote osteoblast activity or increase calcium absorption in the intestines. Choice D is also incorrect as raloxifene does not inhibit the synthesis of collagen.

Correct Answer: C

Rationale: The correct answer is C: Warfarin. Warfarin is an anticoagulant that helps prevent blood clots, reducing the risk of stroke in patients with atrial fibrillation. It is more effective than aspirin or clopidogrel in preventing stroke in this patient population. Heparin is not typically used for long-term stroke prevention in atrial fibrillation.

Correct Answer: B

Rationale: The correct answer is B because salmeterol is a long-acting beta-2 adrenergic agonist, which works by stimulating beta-2 adrenergic receptors on bronchial smooth muscle, leading to bronchodilation. This helps in relaxation of the airways and improved breathing in asthma patients. Option A is incorrect because salmeterol does not affect histamine release. Option C is incorrect as salmeterol does not inhibit leukotriene receptors. Option D is incorrect as salmeterol does not block acetylcholine receptors.