Background As a long acting, slow onset and metabolically neutral compound, calcium channel blocker amlodipine is a well established drug for the treatment of essential hypertension. The aim of the study was to evaluate the efficacy and safety of amlodipine in the form of maleate salt compared with amlodipine in the form of besylate salt in patients with mild to moderate essential hypertension.
Material and methods The study was carried out as a randomized, double blind and parallel trial. It was performed in seven study centers in Poland. Patients, aged 18 to 75 years, with diastolic blood pressure between 95 and 114 mm Hg were included in the study. All enrolled patients were given placebo once daily in a single blind fashion for two weeks. Then patients were randomly assigned to take whether amlodipine maleate or amlodipine besylate 5 mg once daily in a double blind fashion. After 6 weeks of treatment in patients whose diastolic blood pressure remained 90 mm Hg or higher, the dose of each drug was increased to 10 mg once daily. The primary efficacy variable was the mean change in diastolic blood pressure from the end of treatment measured after 12 weeks, to baseline values after placebo run-in period at week 2.
Results 219 patients (mean age 45.5 lat - 154 male, 65 female) were included in the final per-protocol analysis of the efficacy of the studied drugs. After 6 weeks of treatment the drug dose was increased in 47 (43%) and 51 (47%) patients in the amlodipine maleate and amlodipine besylate groups respectively (p = NS). After 12 weeks of treatment the mean change in diastolic blood pressure in the amlodipine maleate group was –17.5 mm Hg compared to the –18.4 mm Hg in the amlodipine besylate group (p = NS). There was no difference in the percentage of patients reaching the goal of diastolic blood pressure lowering to 90 mm Hg between the studied groups (93.6% vs. 92.7%). 35 patients in the amlodipine maleate group and 47 patients in the amlodipine besylate group reported adverse reactions (28.9% vs. 37.9%, p = NS).
Conclusions Amlodipine maleate and amlodipine besylate were equally effective in the treatment of patients with mild to moderate essential hypertension. During 12 weeks of treatment incidence of adverse reactions was comparable in the studied groups.