Amlodipine versus chlorthalidone versus placebo in the treatment of stage I isolated systolic hypertension.

The study was to compare the effects of amlodipine (calcium channel antagonist), chlorthalidone (diuretic), and placebo in adults more than 50 years of age with stage 1 isolated systolic hypertension (ISH). After a 4-week placebo run-in phase, 150 patients were randomly assigned in a double-blind fashion to treatment with 5 mg of amlodipine (n = 48), 15 mg of chlorthalidone (n = 50), or placebo (n = 52). Patients who failed to meet the systolic blood pressure (BP) reduction goal by week 4 had their dose increased to 10 mg of amlodipine or 30 mg of chlorthalidone, and maintained at this increased dose for 12 weeks. Results showed a mean reduction (mean +/- SD) in sitting systolic BP from baseline to the last treatment visit of -14.6+/-12.2 mm Hg (95% confidence interval [CI] -18.2, -11.0), -14.0+/-13.46 mm Hg (95% CI -17.8, -10.2), and -3.4+/-11.83 mm Hg (95% CI -6.7, -0.1) for the amlodipine, chlorthalidone, and the placebo treatment groups, respectively. Both active treatments showed significantly greater reductions than the placebo group (P < or = .001), but were not significantly different from each other. Sixty-seven percent of the amlodipine, 69% of the chlorthalidone, and 25% of the placebo-treated patients reached the protocol defined systolic BP goal (P = .001). Both active treatment groups showed a trend of better systolic BP response in older patients (> or =65 years). Secondary efficacy measures including pulse pressure, standing systolic, diastolic, and the 24-h ambulatory BP were also statistically significantly improved for both active treatments at the end of treatment, except for chlorthalidone in standing diastolic BP. Adverse events that occurred during the study were as expected and were well tolerated. The results of this study support the efficacy and safety of amlodipine and chlorthalidone for the treatment of stage 1 ISH during 20 weeks of treatment.