Comparison of captopril-thiazide and enalapril-thiazide combinations in the management of mild to moderate black hypertensive patients: how important is diuretic dose and duration of action of the ACE-inhibitor?

A double-blind, randomized, parallel-group study was performed to compare the efficacy and tolerability of captopril-thiazide and enalapril-thiazide combinations. After a 3-week placebo run-in period, 47 Black patients with mild to moderate essential hypertension (mean 24-hour diastolic blood pressure (BP) > 90 mmHg and < 115 mmHg) were randomized to receive 1 of 2 combination tablets: captopril 50 mg plus hydrochlorothiazide 25 mg (CAP, n = 24) or enalapril 20 mg plus hydrochlorothiazide 12.5 mg (COR, n = 23) once daily. After 12 weeks of active treatment the mean 24-hour ambulatory BP was reduced from 152 +/- 11/99 +/- 6 to 133 +/- 13/86 +/- 7 mmHg (p < 0.005) in the CAP group and 157 +/- 15/100 +/- 6 to 141 +/- 18/90 +/- 12 in the COR group (p < 0.005). Target BP (24-hour diastolic BP < 90 mmHg) was achieved in 75% (18/24) of patients on CAP and 48% (11/23) on COR (p = n.s.). 24-hour BP load fell significantly with both CAP (from 69% to 34%, p < 0.001) and COR (from 67% to 37%, p < 0.001). Left ventricular mass index decreased by 7% with CAP and 11% with COR. Cardiac index and fractional shortening remained essentially unchanged in both groups. Both treatments were well tolerated and overall incidence of side effects was very low. It is concluded that both CAP and COR are effective, safe first-line antihypertensive choices in Black patients with mild to moderate hypertension with the former showing a trend towards greater efficacy than the latter.