The comparative beta-adrenoceptor blocking effects of penbutolol, atenolol and sustained-release metoprolol in healthy volunteers

Penbutolol and carteolol: two new beta-adrenergic blockers with partial agonism

Penbutolol and carteolol are two new long acting, nonselective beta-adrenergic blockers which have been approved for the treatment of systemic hypertension. Both drugs have intrinsic sympathomimetic activity (partial agonist activity), however, less than that seen with pindolol. They appear to cause less resting bradycardia than propranolol, have no effect on lipids and lipoproteins, and have favorable side effect profiles.

Usefulness of penbutolol for systemic hypertension. Penbutolol Research Group

Dose-response relations with penbutolol--a beta-adrenergic blocking agent--were evaluated in a double-blind multiclinic study conducted in 302 outpatients with mild to moderate hypertension (untreated supine diastolic blood pressure [BP] greater than or equal to 95 and less than or equal to 115 mm Hg). Penbutolol was administered once daily in 10, 20 or 40 mg doses for 6 weeks and compared with placebo. Mean declines from baseline in supine diastolic BP were comparable in the 3 penbutolol treatment groups and significantly superior to placebo (p less than 0.05). A significant difference between penbutolol dosage groups was observed only for supine systolic BP; the mean decline at 20 mg/day was significantly larger than that at 10 mg/day (p less than 0.05). Maximum BP response developed in approximately 4 weeks at 10 mg/day and in 2 weeks at the higher dosages. Decline in mean heart rate after 6 weeks of penbutolol therapy significantly exceeded placebo only at 40 mg/day (7.2 vs 2.5 beats/min, p less than 0.05). Treatment was well-tolerated and discontinued because of adverse effects in only 7 patients receiving penbutolol and 3 receiving placebo. The lack of significant bradycardia and the low incidence of other troublesome adverse effects are potential advantages during antihypertensive therapy with penbutolol. With rapid onset of effect and good efficacy and tolerability, the 20 mg once-daily dose appears to be optimum for therapy with this new agent.