1 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. 2 According to response, patients received doxazosin 1-16 mg day-I 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. 3 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. 4 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 < 0.001) were observed between treatment groups for these parameters, all differences being in favour of doxazosin. 5 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. 6 The incidence of side-effects was slightly greater for patients in the doxazosin group. Drugrelated side-effects were mostly mild to moderate in severity with no serious drug-related occurrences in either treatment group. 7 No serious drug-related abnormalities in laboratory biochemistry and haematology tests were observed in either treatment group.

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SummaryThe antihypertensive effect of labetalol, a new alpha-and beta-adrenoceptor inhibiting agent, was studied in 20 patients in a double-blind crossover trial. A dose of 300 mg daily reduced blood pressure only moderately in the supine position, though in the sitting and standing positions the effect was more pronounced. A dose of 600 mg daily produced statistically significant and clinically relevant reductions in blood pressure in all positions studied. The effect on heart rate was small and of significance only in reducing the heart rate increment due to a change in posture. Side effects were mild: only one patient complained of postural dizziness with the higher dose. We conclude that labetalol is useful in the treatment of mild and moderately severe hypertension.

1 Pindolol and propranolol were administered orally in equipotent antihypertensive doses to 14 subjects with mild to moderate hypertension in an open cross‐over study. 2 Pindolol caused a smaller decrease in plasma renin activity and heart rate than propranolol. 3 Glomerular filtration rate and effective renal plasma flow remained unchanged during therapy with either agent.

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