Prizidilol, an antihypertensive with precapillary vasodilator and β-adrenoceptor blocking actions, in primary hypertension

Single oral doses of 1.5, 3.0, 4.5 and 6.0 mg/kg prizidilol HCl, an antihypertensive with vasodilator and beta-adrenoceptor blocking actions, were given to 12 patients with primary hypertension on separate days. Systolic and diastolic blood pressure (BP) decreased after 4.5 and 6.0 mg/kg and systolic BP also after 3.0 mg/kg. The antihypertensive effect was evident in 1 to 2 hr with maximum effect in 4 to 5 hr (supine systolic BP 20 and diastolic 13 mm Hg after 6.0 mg/kg); the effect was sustained for more than 8 hr. An initial slight reduction in heart rate (HR) after 1 to 2 hr was followed by a slight rise after 6 to 8 hr. There were higher plasma drug levels and greater antihypertensive effects after the 6.0-mg/kg dose in slow acetylators (n = 5) than in rapid acetylators (n = 7). Due to its hydrazine moiety, prizidilol, like hydralazine, seems to be a substrate for the polymorphic N-acetyltransferase enzyme system.