Comparison of the antihypertensive effects of the fixed dose combination enalapril 10 mg/nitrendipine 20 mg vs losartan 50 mg/hydrochlorothiazide 12.5 mg, assessed by 24-h ambulatory blood pressure monitoring, in essential hypertensive patients.

Abstract

Fixed combinations of calcium channel blockers and angiotensin converting enzyme inhibitors represent an alternative to diuretic-based combination therapy. The aim of the present study was to compare the antihypertensive efficacy of the combination enalapril 10 mg/nitrendipine 20 mg (E/N) vs losartan 50 mg/hydrochlorothiazide 12.5 mg (L/H), assessed by 24-h ambulatory blood pressure monitoring. This multicentre, double-blind, parallel study included 97 hypertensive patients (office diastolic blood pressure (DBP) 90-109 mmHg and daytime DBP > 85 mmHg). After a 2- to 3-week period of single-blind placebo, they were randomized to receive double-blind treatment with E/N (n = 48) or L/H (n = 49) for a 4-week period. The primary outcome measure was the difference in 24-h DBP reduction between treatments from randomization to the end of the double-blind period. Secondary efficacy variables included differences in 24-h systolic (S) BP reduction, daytime, night-time and office SBP and DBP reduction, proportion of responders and controlled patients, trough-to-peak ratio and smoothness indexes. Safety was assessed by the proportion of patients with adverse events and the detection of laboratory abnormalities. No significant differences were observed in the primary outcome measure. The group receiving E/N tended to show greater reductions in most measures (24 h, daytime and office SBP and DBP) and higher BP control rates, but only the difference in the rate of office SBP control (< 140 mmHg) reached statistical significance (42.2 vs 22.4%; P = 0.048). The trough-to-peak ratios and smoothness indexes were similar in both groups. The incidence of adverse events related to the treatment was 27.1% (95% CI 14.5-39.6%) in E/N-treated patients and 14.3% (95% CI 4.5-45.8%) in the L/H group, but differences were not significant. The kind of event more frequently observed were flushing and headache in E/N, and dizziness and asthenia in L/H; all observed adverse events were mild. We conclude that E/N and L/H have a similar antihypertensive efficacy, assessed by office or ambulatory blood pressure monitoring. E/N achieved a significantly higher office SBP control rate, but this was accompanied by an apparently higher proportion of mild adverse events.