USMLE Step 1 Question 339

Question:

A 65 year old man with a history of essential hypertension presents with bilateral, non-tender leg swelling for 2 weeks. His hypertension was diagnosed three weeks ago and he is currently taking only one anti-hypertensive. He has no signs or symptoms of congestive heart failure and no edema in other body parts. Which of the following medications is most likely to be responsible for his edema?

Correct Answer: E.  Amlodipine

Amlodipine is a calcium channel blocker. It works by inhibiting transmembrane influx of calcium in peripheral and cardiac vascular smooth muscle. The result is reduced vascular tone, which can relieve coronary vasospasm (angina) and decrease blood pressure.
Vasodilation in peripheral tissues may give rise to vascular leakage. The side effect of lower extremity edema is a common indication for discontinuation of CCB.
HCTZ is a thiazide diuretic that is a first line treatment for essential hypertension. Its main effect is to reduce effective arterial volume via diuresis. Common side effects are hypercalcemia and electrolyte imbalances.
Furosemide is used to relieve volume overload, usually pulmonary edema, in congestive heart failure. It is not a common treatment for isolated essential hypertension. Common side effects are hyponatremia and hypocalcemia, as well as frequent need to urinate.
Enalapril is an angiotensin converting enzyme inhibitor. ACE inhibitors reduce hypertension by blunting the renin-angiotensin system, thus reducing the kidney’s holding on to sodium. The most common side effect of ACE inhibitors is coughing, followed by angioedema (e.g. swollen lips).
Metoprolol is selective beta-1-adrenergic blocker, hence the target tissue is cardiac muscle. Common side effects include bradycardia, exercise-induced syncope, and worsening of obstructive lung disease (though less so than a nonselective beta blocker like propranolol).