24-HOUR ANTIHYPERTENSIVE EFFICACY OF FELODIPINE 10 MG EXTENDED-RELEASE - THE ITALIAN INTER-UNIVERSITY STUDY

We assessed the 24-h antihypertensive efficacy of an extended-release (ER) 10-mg formulation of the dihydropyridine felodipine in mild-to-mo derate essential hypertension [World Health Organization (WHO) stage I -II]. Thirty patients, 23 men and 7 women, aged 37-70 years (mean 53 /- 9 years) participated in a double-blind, randomized, cross-over stu dy of felodipine 10 mg ER versus placebo. An ambulatory daytime diasto lic blood pressure (DBP) >90 mm Hg at the end of a 4-week run-in perio d was necessary to enter the 10-week treatment phase. Twenty-nine pati ents completed the treatment phase. Twenty-two underwent a 2-day singl e-blind placebo follow-up to assess residual drug effects. All patient s underwent ambulatory BP monitoring (ABPM) by Spacelabs 90207 recorde rs. Recorders were programmed to make automatic BP and heart rate (HR) measurements every 15 min throughout the 24 h. Felodipine 10 mg ER si gnificantly (p < 0.01) reduced ambulatory systole BP (SEP) and DBP val ues throughout the 24-h, day (7 a.m. to 11 p.m.) and night (11 p.m. to 7 a.m.) periods, but not influencing average ambulatory HR values. Tr ough-to-peak (T/P) ratios, calculated on the average ambulatory BP val ues measured in the 7-9 a.m. 2-h interval of the second day of ABPM (b efore the new drug administration: trough) and in the 10 a.m. to 12 no on 2-h interval of the first day of ABPM (peak BP-lowering effect), we re 0.71 and 0.58 for SEP and DBP, respectively. Individual T/P calcula tions, after post hoc selection of nonresponders, gave superimposable results, the consistency of which was judged on mean, median, and conf idence intervals (CI). However, the wide variability of the individual TIP ratios suggests that this method cannot be the only means to eval uate the duration of action of an antihypertensive drug by ABPM. The l ong-acting BP-lowering drug effect was clearly shown by the ABPM perfo rmed in the follow-up when SEP and DBP average values of the 24-h, day , and night periods were still reduced. Felodipine 10 mg ER effectivel y reduced BP in patients with mild-to-moderate hypertension, showing p rolonged duration of its antihypertensive action beyond the time of th e next dose.