Double-blind, parallel, comparative multicentre study of a new combination of diltiazem and hydrochlorothiazide with individual components in patients with mild or moderate hypertension

OBJECTIVE: To compare the antihypertensive efficacy and tolerability of a new combination preparation of diltiazem (150 mg) and hydrochlorothiazide (12.5 mg) with the individual constituents in patients with mild/moderate hypertension. DESIGN: Multi-centre, double-blind, randomised parallel group study. PATIENTS: Seventy-one patients with essential hypertension were recruited to the study. TREATMENT: Following completion of the placebo run-in period 63 patients fulfilled the prerandomisation criteria and entered the 10 week treatment period. Patients were randomised to receive either the combination preparation (D 150 mg/H 12.5 mg), diltiazem (150 mg) or hydrochlorthiazide (12.5 mg). The dosage was increased in three patients who had not attained target blood pressure (BP) control after 6 weeks. OUTCOME MEASURES: Response to treatment assessed by change from baseline in clinic and 24 h ambulatory BP. RESULTS: The proportion of patients achieving target BP (a reduction in resting supine diastolic blood pressure (DBP) to below 90 mm Hg or a reduction of 10 mm Hg from baseline) was 80% in the combination group, 55% in the diltiazem group, and 38% in the hydrochlorothiazide group. The respective figures for reduction in supine DBP from baseline were 13.5 mm Hg, 11.2 mm Hg and 5.9 mm Hg. A similar treatment order appeared throughout each of the efficacy variables. BP control throughout the 24 h dosing interval was demonstrated by ambulatory BP monitoring. Each treatment was well tolerated. CONCLUSION: This study provides clear evidence of the efficacy of combination therapy with diltiazem and hydrochlorothiazide in the management of patients with hypertension.