Long acting beta-blockers in the twenty fourth hour.

Fifteen mild to moderate hypertensives were submitted to exercise testing using a bicycle ergometer with a fixed load. Heart rate, blood pressure and ECG were recorded throughout 5 min exercise and 10 min recovery. Oxygen uptake was measured during the final minute of exercise and blood glucose estimation and serum drug levels assessed 5 min after recovery. The above measurements were made after exactly 24 h following seven days administration of 160 mg of long acting (L.A.) propranolol, 200 mg of sustained action (S.A.) metoprolol and two matched placebos. Propranolol L.A. was superior to Metoprolol S.A. in the reduction of exercise induced tachycardia and both drugs were significantly superior to placebos. Both drugs were effective agents for the lowering of resting blood pressure after 24 h but propranolol L.A. was more effective in the lowering of systolic peaks observed during exercise. There was no significant effect upon oxygen uptake and blood glucose. The incidence of side effects was low and showed no significant difference from placebo.