A long-term double-blind comparison of doxazosin and atenolol in patients with mild to moderate essential hypertension.

The efficacy and safety of doxazosin and atenolol were compared following once-daily administration for up to 1 year, with a minimum of 20 weeks' active treatment. According to response, patients received doxazosin 1-16 mg day-1 or atenolol 50-100 mg day-1. Mean daily doses at the final efficacy assessment (between 20 weeks and 1 year) were doxazosin 11.8 mg and atenolol 94.2 mg. Atenolol produced somewhat greater falls in blood pressure than doxazosin. The differences were statistically significant in the supine but not in the standing position. A small mean reduction in heart rate was produced by doxazosin whereas atenolol produced a marked bradycardia. Analysis of the same patient group at 20 weeks revealed similar overall profiles of activity except that atenolol produced greater falls in blood pressure than in the longer term analysis. Serum concentrations of HDL/total cholesterol ratio were raised in the doxazosin treatment group and lowered in the atenolol group. Triglyceride concentrations fell in the doxazosin group and rose in the atenolol group. Significant differences (P less than 0.001) were observed between treatment groups for these parameters, all differences being in favour of doxazosin. Pharmacokinetics of doxazosin, measured at steady state in 36 patients, showed dose-related plasma concentrations, a mean half-life of about 12 h and relatively low intersubject variation. The incidence of side-effects was slightly greater for patients in the doxazosin group. Drug-related side-effects were mostly mild to moderate in severity with no serious drug-related occurrences in either treatment group. No serious drug-related abnormalities in laboratory biochemistry and haematology tests were observed in either treatment group.