Prospective controlled trial of two nifedipine extended release formulations in the treatment of essential hypertension

Abstract

The aim of this study was to assess the pharmacodynamic equivalence of two different slow-release formulations of nifedipine (CAS-21829-25-4). In a prospective, controlled, double-blind clinical trial, 42 patients with essential hypertension (sitting diastolic blood pressure (DBP) 95-114 mmHg) underwent an initial washout, drug free period of 2 weeks, after which they were randomized to receive either 30 mg of nifedipine in the test preparation "XL" (Nifecard) or 30 mg of nifedipine in a reference formulation, "LA", during six weeks. The response to treatment was assessed by measuring the blood pressure (BP) every two weeks (standard office mercury sphygmomanometry) and by 24-h ambulatory blood pressure monitoring (ABPM). Of the 42 included patients 36 (85.5%) completed the trial: 19 on "XL" and 17 on "LA". After 2 weeks of therapy the DBP decreased by about 11% (-13.4 mmHg) and 10% (-9.5%), respectively, after 4 weeks the mean decrease versus the end of the placebo period reached about 14% (-15.5 mmHg) and 11% (-13 mmHg), and at the end of the trial the DBPs were lower by about 13% (-14.5 mmHg) in both groups. In all these measurements the within group differences were significant (p < 0.001), while the between groups differences were not (p > 0.05). Quite comparable results were obtained with ABPM, e.g. in the "XL" group the systolic blood pressure at the end of the study was lower by 12.3% (-4.6 mm Hg) and in the "LA" group, by 10.6% (-9.0 mm Hg); p = 0.358. The adverse effects were similar in both groups and they required neither particular interventions nor withdrawal from the study. The drugs under study were comparably effective and well tolerated antihypertensives.