Medroxalol combined with hydrochlorothiazide in the treatment of hypertension.
The antihypertensive effect and safety of hydrochlorothiazide administration as a single drug and together with medroxalol were determined in 20 patients with primary hypertension. Following two biweekly intervals on placebo and hydrochlorothiazide, medroxalol was started at 100 mg three times a day and titrated against blood pressure response up to a maximum of 300 mg three times a day. In nine patients the effect of the single and the combined drug therapy on blood pressure during isometric handgrip exercise, on plasma renin activity, and on plasma catecholamines and their deaminated metabolites was investigated. The administration of hydrochlorothiazide was associated with a significant decrease in blood pressure, but heart rate did not change. The addition of medroxalol produced a substantial decrease in blood pressure and heart rate in both the recumbent and upright positions (P less than 0.001). Due to careful titration of medroxalol, orthostatic hypotension was observed only in one patient. Neither hydrochlorothiazide alone nor the combined drug regimen prevented or diminished the rise in blood pressure with exercise. Although plasma renin activity decreased during the combined drug therapy, there was no correlation between the initial levels or the change in plasma renin activity and the extent of decrease in blood pressure. The concentration of plasma epinephrine increased during the combined drug period, whereas catecholamine metabolites increased significantly during both periods of the study. It is concluded that medroxalol combined with hydrochlorothiazide constituted a potent and safe antihypertensive therapy for the duration of the present study.