A controlled trial of labetalol (Trandate), propranolol and placebo in the management of mild to moderate hypertension.

1. Labetalol, a new drug combining alpha-and beta-adrenoceptor blocking properties, has been compared with placebo in a double-blind crossover study of a group of patients with mild to moderate essential hypertension (blood pressure 150/100 to 189/114 mmHg). 2. Labetalol and propranolol lowered blood pressure satisfactorily in the supine position, but labetalol reduced blood pressure more in the erect posture and following exercise and induced less bradycardia. Thus alpha- as well as beta-adrenoceptor blocking actions appear to contribute to blood pressure reduction. 3. Side effects attributable to labetalol were few. The effective dose ratio labetalol: propranolol was 2.5:1 (w/w). 4. Labetalol, a new form of hypotensive agent, merits further controlled assessment of its usefulness in relation to existing drugs.