Doxazosin versus nitrendipine: a double-blind comparative study in patients adhering to a sodium-restricted diet.

The aim of this double-blind parallel-group study was to compare the effects of doxazosin, a selective alpha 1-adrenoceptor antagonist with a long plasma half-life, with nitrendipine, a long-acting calcium-entry blocking drug. Following a 4-week placebo period, 26 patients with mild-to-moderate essential hypertension were randomly allocated to treatment with either doxazosin (n = 12) or nitrendipine (n = 14). Over a period of 10 weeks, doses were titrated to obtain a standing diastolic pressure below 90 mmHg. Thereafter, optimal doses were continued for another 4 weeks. Both drugs were administered once daily; median doses were 4 mg/day for doxazosin and 10 mg/day for nitrendipine. During the titration period three patients in the doxazosin group and one in the nitrendipine group dropped out from the study; one patient on doxazosin was considered a nonresponder. Twenty-one patients completed the study. The percentage of patients showing an adequate hypotensive effect (standing diastolic pressure below 90 mmHg) at the end of the study was similar in the two groups (42% vs. 50% in the intention-to-treat analysis and 56% vs. 54% in the per-protocol analysis). Casual, basal, and standing blood pressure and heart rate did not differ between groups throughout the study; serum lipids and blood glucose remained unchanged. We conclude that doxazosin and nitrendipine given as monotherapy are equally effective in mild to moderate hypertension.