A double-blind crossover comparative study of the efficacy of single daily doses of conventional and slow-release metoprolol.

The antihypertensive effect of slow-release metoprolol was studied in 50 patients suffering from mild to moderate essential hypertension. In a double-blind crossover study, the effect of slow-release metoprolol was compared with conventional metoprolol for efficacy and tolerability in 40 patients. After a 2-week period on placebo, patients received either 200 mg slow-release metoprolol once daily or 200 mg conventional metoprolol once daily for 6 weeks before crossing over to the alternative dosage form for a further 6 weeks. The results showed that both slow-release and conventional metoprolol were equipotent and reduced significantly the pulse rate and also the supine, sitting and standing systolic and diastolic blood pressures. Slow-release metoprolol also reduced the exercise blood pressure in 10 patients following 2-weeks' administration of 200 mg daily in a single dose. Good patient compliance with the medication was observed. No adverse effect attributable to slow-release metoprolol or conventional metoprolol was detected throughout the study.