Low-dose reserpine/thiazide combination in first-line treatment of hypertension: Efficacy and safety compared to an ACE-inhibitor

Abstract

The concept of initiating treatment of mild-to-moderate hypertension with a low-dose combination of reserpine and the thiazide clopamide in comparison to monotherapy with an ACE inhibitor was investigated. A total of 127 adult outpatients with diastolic blood pressure between 100 and 114 mmHg were randomized into this double-blind, parallel group study. After a 2-week wash-out period and a subsequent 2-week placebo run-in period, they were allocated to once-daily treatment with 0.1 mg reserpine plus 5 mg clopamide (R/C), or 5 mg enalapril. If diastolic blood pressure was not normalized after 3 weeks of therapy (i.e. DBP < 90 mmHg), the dosage was doubled from week 4 to 6. The primary efficacy variables were the change from baseline in mean sitting diastolic and systolic blood pressure (DBP/SBP) after 3 weeks of therapy. Secondary variables included the change in DBP and SBP after 6 weeks of therapy, the BP normalization rates at 3 and 6 weeks and, concerning tolerability, the rates of adverse events after 6 weeks of therapy. An intent-to-treat analysis was performed. The reserpine/clopamide and enalapril groups did not differ with regard to demographic and baseline characteristics (mean age 57 or 58 years, respectively; 63% or 56% males, respectively; mean SBP/DBP after the 2-week placebo period = 156 mmHg/104 mmHg in both groups). After 3 weeks of treatment with one capsule daily, mean SBP/DBP reduction from baseline (24 h after last medication intake) in the R/C combination group was -19.6/-17.0 mmHg, in the enalapril group -6.1/-9.5 mmHg (between- group comparison: 2p < 0.01 for both parameters). The normalization rates for DBP (< 90 mmHg) were 64.1% (R/C) and 28.6% (enalapril) (2p < 0.01). Adverse events that were considered possibly or definitely drug-related by the investigator were noted in 11 patients (17.2%) in the R/C group and in 9 patients (14.3%) in the enalapril group (NS). Two patients in the enalapril group discontinued the study prematurely due to adverse events (cough; skin eruption). In the treatment of mild-to-moderate hypertension, a low-dose combination of reserpine and clopamide once a day is considerably more effective than, and as tolerable as, 5-10 mg of enalapril once a day. These findings suggest that treatment with a combination of different antihypertensives with different modes of action in low doses is a rational alternative to conventional monotherapy in the first-line treatment of hypertension. Besides, the 'old' reserpine-diuretic regimen also in these days appears to be a rational alternative to 'modern' monotherapies.