A double-blind comparative study of doxazosin and nitrendipine in patients with mild-to-moderate essential hypertension

Abstract

The antihypertensive efficacy and safety of doxazosin, a selective α 1-inhibitor, were compared with nitrendipine. Seventy-two hypertensive patients were entered into the 18-week, double-blind parallel group study, which involved three phases: a 4-week baseline period, a 10-week period in which patients received 1 to 8 mg of doxazosin or 10 and 20 mg of nitrendipine once daily, and a 4-week maintenance period. For all patients, the mean final daily doses were 2.5 mg for doxazosin and 13.9 mg for nitrendipine. In efficacy evaluable patients the percentages of therapy successes (standing diastolic blood pressure ≤90 mm Hg with ≥5 mm Hg reduction or ≥10 mm Hg decrease) were comparable for doxazosin (94%) and nitrendipine (91%), as was the proportion in whom blood pressure was “normalized” (standing diastolic blood pressure ≤90 mm Hg). 91% and 85, respectively. Blood pressures (diastolic and systolic in supine and standing positions) were significantly reduced ( p < 0.05) at all visits in both treatment groups. Ten patients (28%) in each treatment group experienced at least one adverse event. No clinically significant laboratory changes were apparent in either the doxazosin or nitrendipine groups, and no trends were observed with regard to organ systems or correlations with dose or duration of treatments. The investigators' global assessment of efficacy was rated excellent or good for all doxazosin-treated patients and excellent or good for 32 and fair for four in the nitrendipine group. The investigators' global assessment of patient toleration of doxazosin was excellent or good for 34 patients and poor for two. Toleration of nitrendipine was excellent or good in 33 patients and fair in three. Lipid parameters did not differ significantly between groups. From baselline to final visit there were highly significant reductions ( p < 0.001) in the calculated coronary heart disease risk scores on the basis of the Framingham equation, for both treatment groups.