ANTIHYPERTENSIVE EFFECTS OF MIBEFRADIL - A DOUBLE-BLIND COMPARISON WITH DILTIAZEM-CD

Background and hypothesis: Mibefradil is the first compound of a new c lass of calcium antagonists with a unique chemical structure and mecha nism of action. This trial compared mibefradil with diltiazem CD, a wi dely prescribed calcium antagonist for the treatment of hypertension. Methods: In all, 201 patients with uncomplicated, mild-to-moderate ess ential hypertension with a baseline sitting diastolic blood pressure ( SDBP) of greater than or equal to 95 and less than or equal to 114 mmH g were evenly randomized to receive either mibefradil (100 mg) or dilt iazem CD (360 mg) daily for 12 weeks. To determine whether antihyperte nsive effects persisted after 12 weeks, patients then entered a 4-week withdrawal period during which they remained on active treatment or w ere switched to placebo. Results: Efficacy variables were the changes from baseline in SDBP to the end of the treatment period (Week 12) and during the randomized withdrawal period (Week 16). At Week 12, the re duction from baseline in SDBP at trough was significantly greater (p<0 .001) in the mibefradil group (- 14.0 +/- 7.8 mmHg) than in the diltia zem CD group (-9.5 +/- 7.5 mmHg). Significantly more patients (72%) on mibefradil achieved SDBP normalization by Week 12 than did patients o n diltiazem (51%) (p<0.01). Patients maintained on mibefradil or dilti azem CD during the withdrawal period had a significantly larger reduct ion in trough SDBP at Week 16 than those switched to placebo. The inci dence of side effects was similar in both treatment groups. Conclusion s: Once-daily mibefradil was equally well tolerated as diltiazem CD, b ut was more effective in lowering blood pressure at the doses studied than the extended-release formulation of diltiazem.