Anti-Anginal and Anti-Ischemic Effects of Mibefradil, a New T-Type Calcium Channel Antagonist

Abstract

Mibefradil is the first of a new class of calcium antagonists (CAs), the tetralol derivatives, that selectively blocks the T-type calcium channel. The anti-anginal and anti-ischemic efficacy of mibefradil in patients with chronic stable angina pectoris was established in five placebo-controlled trials (2 monotherapy trials, 3 trials with background β-blocker or long-acting nitrate therapy). At the recommended doses of 50 and 100 mg, mibefradil treatment was associated with a significant dose-related increase in exercise test variables regardless of demographic subpopulation or background therapy. Significant reductions in weekly anginal attacks, silent ischemic parameters, heart rate (HR) and rate-pressure product were also observed. Two active-controlled trials compared mibefradil 100 mg with amlodipine 10 mg or diltiazem SR 120 mg b.i.d., respectively. Patients receiving mibefradil showed significantly larger improvements than did those treated with amlodipine and similar improvements as those treated with diltiazem SR in all variables measured. In both studies, treatment with mibefradil was associated with a greater decrease in HR and rate-pressure product. Mibefradil was found to be well tolerated and safe; this held true for patients on chronic anti-anginal background therapy. The overall incidences of adverse events and premature withdrawals were only slightly higher than those of placebo-treated patients. Asymptomatic sinus bradycardia and first-degree atrioventricular block were the most frequently occurring mibefradil dose-related ECG changes. Mibefradil was better tolerated than amlodipine (mainly with regard to leg edema) and similarly well tolerated as diltiazem CD.