EFFECTS OF AMLODIPINE ONCE-DAILY ADMINISTRATION ON BLOOD-PRESSURE CIRCADIAN PROFILE EVALUATED BY NONINVASIVE 24-HOUR AMBULATORY BLOOD-PRESSURE MONITORING - INFERENTIAL ANALYSIS OF AN OPEN NONCOMPARATIVE STUDY

Blood pressure (BP) is characterized by a periodical circadian trend, which reflects some hemodynamic and cardiovascular changes. In compari son with office BP measurements, one of the most useful tools to evalu ate pressure variability seems to be 24-hour ambulatory blood pressure monitoring (ABPM). To verify the antihypertensive efficacy of amlodip ine and its possible influence over the circadian BP profile, we studi ed 20 patients (12 men, 8 women), mean age 49 years, who were affected by mild-to-moderate essential hypertension (supine and standing diast olic BP = 95 to 114 mmHg). After a 2-week pharmacologic washout period and at the end of 26 weeks of treatment with amlodipine (10 mg once d aily), the patients underwent ABPM with a Spacelabs 90207. During this period, timely clinical and laboratory tests were done to evaluate th e office BP and possible side effects. The data obtained were interpre tated by ''traditional'' statistical methods and by inferential analys is (statistical study of mathematical functions, deriving from origina l series extrapolation), by means of Fourier model with four harmonics . BPs were significantly reduced by amlodipine over 24 hours without s ignificant changes in heart rate (HR). BP fell during the night and th e slope of BP morning rose--time of maximum incidence of myocardial is chemia and stroke-appeared to be significantly controlled by amlodipin e. These results confirm that amlodipine can be considered a first-cho ice drug in patients with cardiovascular risk factors because of its r ole in BP day-long control, particularly at awakening. Once-daily admi nistration and few drug side effects enhanced patient compliance and a llowed more satisfying therapeutic results. The four harmonics Fourier model could improve the traditional statistical methods for 24-hour A BPM interpretation, for a correct evaluation of BP long-term variabili ty.