1. Nine men aged 20–33 years with essential hypertension measured their own blood pressure at home, lying and standing, three times daily, under conditions of everyday living. The last 14 days' readings (eighty-four observations) from control and treatment periods of at least 4 weeks’ duration were used to calculate mean pressures.
2. In eight patients, propranolol (40 mg thrice daily with meals) significantly lowered ‘mean blood pressure’ (diastolic + ⅓[systolic — diastolic]) but methyclothiazide (5 mg with breakfast) did not. In five subjects, prindolol (5 mg thrice daily with meals) significantly lowered ‘mean blood pressure’ but methyclothiazide (5 mg with breakfast) did not.
3. In six subjects there was no significant difference between ‘mean blood pressure’ when taking propranolol doses 120 mg with breakfast, 60 mg with breakfast and with the evening meal, and 40 mg with each meal. In five subjects there was no significant difference between ‘mean blood pressure’ when taking metoprolol 200 mg with breakfast and 100 mg with breakfast and with the evening meal. In four subjects there was no significant difference between ‘mean blood pressure’ when taking prindolol 30 mg with breakfast, 15 mg with breakfast and with the evening meal, and 10 mg with each meal.
4. In young males with essential hypertension, β-adrenoreceptor blockers were more effective than a thiazide diuretic in lowering blood pressure, and were effective in a single daily dose.
