EQUIVALENT BLOOD-PRESSURE REDUCTION AND TOLERABILITY WITH CONTROLLED-RELEASE METOPROLOL 50MG ONCE-DAILY AND CONVENTIONAL METOPROLOL 50MG TWICE-DAILY - A DOUBLE-BLIND 8-WEEK COMPARISON IN HYPERTENSIVE PATIENTS

In a prospective, multicentre, double-blind, parallel group study, the blood pressure-lowering effects of an oral 50mg once-daily dosage of metoprolol CR/ZOK (controlled-release/zero-order kinetics), an agent w ith 24-hour activity, were compared with those of conventional oral me toprolol 50mg twice daily in patients with mild to moderate hypertensi on. After a 2-week placebo washout phase, 54 patients were treated wit h metoprolol CR/ZOK and 55 patients received conventional metoprolol f or 8 weeks. The target variables of blood pressure and heart rate were measured in the supine and standing positions at rest, under standard ised conditions, in the morning and evening after 4 weeks' treatment a nd at the end of the 8-week treatment phase. After 8 weeks, blood pres sure and heart rate at the end of the respective dosage intervals were significantly reduced from baseline in both treatment groups. Mean sy stolic and diastolic blood pressures measured in the morning, 12 hours after conventional metoprolol and 24 hours after metoprolol CR/ZOK, w ere 16.8/11.0mm Hg and 16.2/11.2mm Hg, respectively, lower than baseli ne values. Heart rate after 8 weeks' treatment was reduced by 9.0 beat s/min with metoprolol CR/ZOK and by 9.3 beats/min with conventional me toprolol. The small deviations in the 95% confidence intervals demonst rate the equal efficacy of the 2 preparations. Approximately the same number of patients in the 2 groups reported adverse events. Even thoug h not significant, the total number of adverse events was 25% lower in metoprolol CR/ZOK recipients. The results of this study confirm that once-daily oral metoprolol 50mg administered as a controlled-release f ormulation with 24-hour activity and zero-order kinetics constitutes a n effective treatment for most patients with mild to moderate hyperten sion. In addition, antihypertensive efficacy with this formulation is achieved at half the dosage required with conventional metoprolol.