[Circadian antihypertensive action and tolerability of a sustained-release form of isradipine in an intra-individual comparison with nitrendipine]

Abstract

Antihypertensive efficacy and tolerability of a 4-week treatment each with the modified release formulation of the calcium antagonist isradipine (5 mg; Lomir SRO, CAS 75695-93-1) were compared with those of nitrendipine (20 mg) (both with morning intake) in 51 patients with mild to moderate hypertension using a double-blind, intraindividual crossover study. Blood pressure was measured over 24 h at the end of a 2-week placebo phase and after both treatment phases by means of a continuous ambulatory recording device. Upon statistical evaluation of all patients with 3 complete 24-h profiles (n = 44) and combined analysis of data from same treatments the following 24-h mean values were obtained: blood pressure (syst./diast.) was lowered from 151/98 mmHg to 141/91 mmHg by isradipine retard (IS) and to 141/92 mmHg by nitrendipine (NI), whereas heart rate remained nearly unchanged (78 vs 79 beats/min on both therapies). The 24-h profiles differed significantly between placebo and both therapies, the profile as a whole was more even on IS. Starting from a day-time mean value (6:00 a.m.-10:00 p.m.) on placebo of 155/102 mmHg blood pressure was reduced by IS to 143/94 mmHg and by NI to 144/95 mmHg; the corresponding night-time mean values were; placebo 138/85 mmHg, IS 132/82 mmHg, NI 134/83 mmHg. If one compares the area under the blood pressure curves during the hours from 6 p.m. to 12 p.m. significant differences (2p = 0.0128) were found for systolic pressure and borderline significance (2p = 0.0668) for diastolic differences in favour of IS.