Comparison of amlodipine and enalapril in the treatment of isolated systolic hypertension in the elderly: an open-label, randomized, parallel-group study

Background: The benefits of treating isolated systolic hypertension (ISH) are well established, but the most appropriate drug choice is still uncertain.Objective: The purpose of this study was to compare amlodipine, a calcium channel blocker, with enalapril, an angiotensin-converting enzyme inhibitor, in the treatment of ISH in a cohort of elderly patients (≥60 years of age).Methods: Ambulatory patients with ISH (seated systolic blood pressure SBP] >160 mm Hg and <220 mm Hg; diastolic blood pressure DBP] <95 mm Hg) who had not been treated previously or who had stopped their medication at least 4 weeks before the study were enrolled. Patients were randomized to receive amlodipine 5 mg/d or enalapril 10 mg/d. After 4 weeks of treatment, the dose was doubled for those patients whose sitting SBP had not decreased to <150 mm Hg or by >20 mm Hg, and treatment was continued for an additional 4 weeks.Results: A total of 89 patients were randomized to treatment, 46 to amlodipine and 43 to enalapril; 1 patient in the enalapril group died due to ischemic stroke despite adequate blood pressure control. The absolute reductions in seated and standing SBP/DBP were similar with both drugs after 8 weeks: 27 mm Hg/4.6 mm Hg with amlodipine and 23.9 mm Hg/3.9 mm Hg with enalapril (sitting) and 25.1 mm Hg/4.1 mm Hg and 21.3 mm Hg/4.2 mm Hg (standing) with amlodipine and enalapril, respectively (P = NS). At 4 weeks, 24 patients (52.2%) in the amlodipine group and 33 patients (76.7%) in the enalapril group had their medication dose doubled because their SBP was not adequately controlled with the initial dose (P < 0.01). At the end of the study, 24 patients were taking 10 mg amlodipine and 22 patients were taking 5 mg (mean dose 7.6 ± 2.5 mg); 33 patients were taking 20 mg enalapril and 10 patients were taking 10 mg (mean dose 17.8 ± 4.1 mg). Side effects occurred significantly more frequently in the amlodipine group (P = 0.01).Conclusion: The results of this study suggest that amlodipine and enalapril are similarly effective in treating ISH in elderly patients, with few side effects.