Open Comparative Study to Assess the Efficacy and Safety of Two Calcium Antagonists

Abstract

The efficacy and safety of amlodipine (5-10 mg once daily) and diltiazem (30-60 mg three times daily) were compared in 40 patients with symptomatic myocardial ischemia. A 2-week placebo run-in period was followed by 10 weeks of open treatment with amlodipine (n = 20) or diltiazem (n = 20). Concomitant treatment with other antianginal drugs (except other calcium antagonists) was permitted throughout the study. The baseline blood pressures were 166/93 and 160/91 mm Hg for the amlodipine group and diltiazem groups, respectively. Amlodipine (mean final daily dose of 9.25 mg) reduced blood pressure by - 27/-11 mm Hg compared with a reduction of - 17/-8 mm Hg for diltiazem (mean final daily dose of 180 mg), with no significant effects on heart rate. A significantly greater reduction in the mean rate-pressure product was observed after amlodipine (-20.8%) when compared with diltiazem (-13.1%) (p < 0.05). Amlodipine reduced the mean weekly angina attacks to zero after 6 weeks of treatment (baseline of 3.4 attacks/week) compared with a reduction from 3.3 to 0.35 attacks/week after 10 weeks of treatment with diltiazem. The amlodipine group had a reduction in mean nitroglycerin consumption from baseline of 1.1 mg/week to zero by week 6, whereas the diltiazem group had reduced mean weekly intake from 0.9 to 0.1 mg at the end of the study. The overall assessment of clinical efficacy was excellent for 100% of amlodipine patients compared with 40% of diltiazem patients. The high-density lipoprotein cholesterol/total cholesterol ratio increased by 15.8% with amlodipine compared to diltiazem, which produced a 4.5% decrease. Amlodipine decreased triglycerides by 7.1% compared to 4.5% with diltiazem. The incidence and severity of side effects was comparable for both treatments. Amlodipine once daily was effective and well tolerated in the treatment of patients with symptomatic myocardial ischemia and was comparable with diltiazem three times daily.