Review Question - QID 108864

This patient most likely developed peripheral edema after starting a dihydropyridine calcium channel blocker (CCB). Nifedipine and amlodipine are dihydropyridine CCBs.

In this patient with new onset lower extremity swelling following initiation of a new medication, an adverse effect should be suspected. Peripheral edema is a common side effect of CCBs which act by blocking voltage-gated L-type calcium channels, leading to muscle relaxation. There are two types of CCBs: dihydropyridines and non-dihydropyridines. Dihydropyridine CCBs include nifedipine and amlodipine and non-dihydropyridine CCBs include verapamil and diltiazem. Dihydropyridine CCBs are more selective for the peripheral vasculature while non-dihydropyridine CCBs are more selective for the heart, with verapamil being more cardioselective than diltiazem. Given this selectivity, verapamil is less frequently prescribed for hypertension, so the most likely medication in this vignette is nifedipine. Moreover, peripheral edema is more common in dihydropyridine CCBs due to their selectivity for the peripheral vasculature.

Incorrect Answers:
Answer 1: Metoprolol is a beta-1 adrenergic antagonist. Adverse effects of metoprolol include bradycardia, dizziness, and fatigue.

Answer 2: Verapamil is a non-dihydropyridine CCB. Given its selectivity for the heart, it is rarely prescribed as an anti-hypertensive. The most common side effect of verapamil is constipation.

Answer 4: Hydrochlorothiazide is a thiazide diuretic. Adverse effects of thiazides include metabolic disturbances (e.g., hypokalemia, hypercalcemia, hyponatremia, hyperuricemia, and hyperglycemia), photosensitivity, and weight gain.

Answer 5: Spironolactone is a mineralocorticoid receptor antagonist. Its adverse effects include hyperkalemia, urinary frequency, hypotension, and gynecomastia.

Bullet Summary:
Peripheral edema is an adverse effect of dihydropyridine calcium channel blockers.