Precipitous hypotension after nifedipine in pheochromocytoma: report of 2 cases.

Two patients with pheochromocytoma initially responded to oral or sublingual nifedipine with marked reduction in systolic blood pressure (range 50-160 mmHg) without concomitant increment in the heart rate or clinical consequences. This could possibly be due to the combination of hypovolemia and negative inotropism.