Background A nine-month follow-up, multicenter study was carried out to assess the efficacy and safety of amlodipine maleate, a recently launched amlodipine salt in 263 patients with essential hypertension.
Material and methods In the first phase of the trial, a 3-month equivalence assessment with the reference besylate salt has been carried out in a randomised doubleblind fashion including placebo run-in period. The equivalence margins were set to be ± 4 mm Hg. The second phase was a 6-month open non-comparative extension of the equivalence phase to provide additional information on clinical efficacy and acceptability during prolonged treatment with amlodipine maleate. Essential hypertension was defined as a sitting diastolic blood pressure (DBP) being within the range of 95-114 mm Hg and systolic blood pressure below 180 mm Hg. An adequate blood pressure control defined as reaching the target DBP of 89 mm Hg or at least 10 mm Hg reduction of DBP compared to the baseline values, was the inclusion criterion for the second phase. The primary endpoint was the mean absolute reduction of DBP at the end of the active treatment in relation to the baseline.
Results Altogether, 245 patients were analyzed in the equivalence comparative part, while 202 patients were included in the analysis of the open follow-up period. Both drugs have significantly lowered DBP and SBP after 3 months of treatment compared with the baseline values while heart rate has not been significantly changed in any of the treatment groups. The difference in these parameters between the salts was not significant. The difference in DBP reduction between the treatments was 1.27 mm Hg in favour of the besylate salt and the 90% confidence interval fell entirely within the equivalence margins. There was no difference between the salts in the percentage of patients reaching the target DBP (90.91% and 89.52% for maleate and besylate, respectively). The DBP/SBP reduction after the amlodipine maleate at the end of the 6-month second phase was –17.5/–21.2 mm Hg compared to the baseline values (paired t test, p < 0.0001). Blood pressure control was adequate during the second phase. Thirty-five patients in the amlodipine maleate group and 47 patients in the amlodipine besylate group reported adverse reactions during the 3-month comparative (28.9% and 37.9%, for maleate and besylate, respectively, p = NS). The overall incidence of amlodipine maleate-related adverse events during the second phase was 8.4%.
Conclusions In conclusion, amlodipine maleate was shown to be equivalent to the reference besylate salt in terms of antihypertensive efficacy, and safety profiles of the two salts were not significantly different. Amlodipine maleate enabled adequate blood pressure control and was shown to be well tolerated during the entire 9-month follow-up.