CIRCADIAN ANTIHYPERTENSIVE EFFICACY AND T OLERABILITY OF A SLOW-RELEASE ISRADIPINE FORMULATION INTRAINDIVIDUALLY COMPARED WITH NITRENDIPINE

Antihypertensive efficacy and tolerability of a 4-week treatment each with the modified release formulation of the calcium antagonist isradi pine (5 mg; Lomir SRO(R), CAS 75695-93-1) were compared with those of nitrendipine (20 mg) (both with morning intake) in 51 patients with mi ld to moderate hypertension using a double-blind, intraindividual cros sover study. Blood pressure was measured over 24 h at the end of a 2-w eek placebo phase and after both treatment phases by means of a contin uous ambulatory recording device. Upon statistical evaluation of all p atients with 3 complete 24-h profiles (n = 44) and combined analysis o f data from same treatments the following 24-h mean values were obtain ed: 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 p lacebo 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 b y NI to 144/95 mmHg; the corresponding night-time mean values were: pl acebo 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 diffe rences in favour of IS. Also tolerability of IS was significantly bett er: adverse events, typical for dihydropyridines, with relation to stu dy drug were observed in 5 patients on IS (5 entries) and in 11 patien ts on NI (20 entries). Likewise, the number of nearly normotensive res ponders on IS (15 out of 44) was greater than that on NI (10 out of 44 ). Altogether, 5 mg IS has proven more efficacious and tolerable in an tihypertensive therapy than 20 mg of NI given once daily.