A randomised, double-blind trial comparing mibefradil and amlodipine: two long-acting calcium antagonists with similar efficacy but different tolerability profiles

Abstract

Objective: To compare the efficacy and tolerability of mibefradil and amlodipine in patients with uncomplicated mild-to-moderate essential hypertension. Design: A double-blind, randomised, parallel group multicentre trial. Methods: 239 patients received 50 mg mibefradil or 5 mg amlodipine for 4 weeks, followed by a forced titration to 100 mg mibefradil or 10 mg amlodipine for an additional 8 weeks. Patients then entered a 4-week withdrawal period either on therapy or switched to placebo. Results: Statistically equivalent reductions in trough sitting diastolic blood pressure (SDBP) were observed after 12 weeks of once-daily treatment with 50/100 mg mibefradil (−11.5 ± 8.2 mm Hg) and 5/10 mg amlodipine (−13.2 ± 7.9 mm Hg). The number of patients with normalised SDBP (⩽90 mm Hg) increased 23.3% in the mibefradil group and 19.5% in the amlodipine group (approximately 74% in both groups). Patients on mibefradil or amlodipine during the withdrawal period had significantly larger decreases in SDBP than those on placebo. Patients on mibefradil had a decrease in heart rate of 5.5 bpm. Patients on amlodipine had no change in heart rate; however, cessation of amlodipine was associated with a decrease in heart rate. Conclusions: Mibefradil was as effective as amlodipine in reducing BP; both compounds were effective treatments of hypertension.