Prazosin and propranolol in preoperative management of pheochromocytoma

Combined use of prazosin and propranolol was effective in preoperative management of three patients with norepinephrine(NE)-secreting pheochromocytoma (PHEO). On admission, all were symptomatic and had moderate to severe hypertension despite treatment with diuretics, propranolol, and sympatholytics. Optimal symptomatic and blood pressure (BP) control was achieved with 6 to 10 mg/day prazosin and 120 to 480 mg/day propranolol every 6 hr in equally divided doses. With this therapy, BP and hematocrit were reduced to levels similar to those found in the postoperative period. The daily urinary excretion of catecholamines and their metabolites was not modified during therapy with prazosin and propranolol. There was a drop in supine systolic (40 to 64 mm Hg) and diastolic (32 to 52 mm Hg) BP in all patients 1 to 2 hr after the first dose of prazosin (1-mg tablet); in two subjects this was accompanied by a larger orthostatic fall (74 and 92 mm Hg systolic; 65 and 78 mm Hg diastolic BP). The high incidence of first-dose effect suggests that a single oral dose of 1 mg of prazosin could aid in the diagnosis of PHEO. The effectiveness of prazosin in controlling the hypertension induced by NE-secreting PHEO suggests that, in man, pressure responses to augmented levels of NE are mediated solely through αl-receptors.