A multicentre study to compare the therapeutic efficacy of sustained-release diltiazem and enalapril in the treatment of patients with mild to moderate hypertension.

A 14-week study was conducted in order to compare the efficacy and tolerability of a twice-daily sustained-release diltiazem preparation (120 or 180 mg) and once-daily enalapril (10 or 20 mg). Patients not achieving an adequate response after 6 weeks on monotherapy were given a combination therapy of twice-daily diltiazem 120 mg and once-daily enalapril 10 mg. Of the 147 patients admitted to the study, 70 received diltiazem and 77 received enalapril; 17 patients subsequently received combination therapy. Blood pressure reductions in patients completing 12 weeks of therapy were (sitting values): diltiazem 120 mg, 10.2/15.2 mmHg; diltiazem 180 mg, 19.1/14.7 mmHg; enalapril 10 mg, 25.7/17.5 mmHg; enalapril 20 mg, 19.6/14.0 mmHg; and combination therapy, 24.6/15.1 mmHg. No significant differences in the incidence level of individual symptoms were seen between the two groups: 34 (49%) in the diltiazem, 37 (48%) in the enalapril group; and, between weeks 6 and 12, 9 (53%) patients taking combination therapy. Two patients withdrew from the enalapril group and 8 from the diltiazem group. No unexpected side-effects were seen during the study and no deaths occurred in any treatment group. Twice-daily sustained-release diltiazem 120 or 180 mg was shown to be an effective antihypertensive agent and equal in efficacy and patient acceptability to once-daily enalapril 10 or 20 mg. Combination therapy effectively lowered blood pressure in patients in whom monotherapy was ineffective.