THE EFFECT OF AMLODIPINE ON AMBULATORY BLOOD-PRESSURE IN HYPERTENSIVEPATIENTS

Certain high-risk populations, such as diabetics and blacks, have sust ained elevation in blood pressure and heart rate throughout the day an d night, with blunting of the usual diurnal variability pattern. This may contribute to their higher incidence of left ventricular hypertrop hy (blacks) and cardiovascular complications (diabetics). Hypertensive s who maintain a diurnal pattern of blood pressure variation still exh ibit higher daytime and nocturnal blood pressure levels than normotens ives. Thus, to achieve maximum effectiveness in treating hypertension, 24-hour control of blood pressure is necessary. Antihypertensive agen ts should effectively reduce blood pressure consistently throughout a 24-hour period. The objective of this study was to assess the effects of amlodipine, 5 mg once daily, on blood pressure measured by 24-hour ambulatory monitoring in a randomized, double-blind, placebo-controlle d single-site study. Patients with mild to-moderate essential hyperten sion were randomized to receive amlodipine (n = 11) or placebo (n = 5) in a 2:1 ratio. A 4-week single-blind placebo run-in period was follo wed by a 4-week double-blind phase. Ambulatory monitoring of blood pre ssure was carried out for 24 hours at the end of each 4-week phase. Pa tients receiving amlodipine had significantly lower blood pressure com pared with placebo 24 hours after the last dose (supine blood pressure -25.1/-10.1 mm Hg; standing blood pressure -21.2/-9.7 mm Hg) after 4 weeks of treatment. This effect was clearly demonstrated by the 24-hou r postdose measurement and the mean blood pressure over the 24-hour in terval as measured by ambulatory recordings. The mean hourly ambulator y recordings showed that amlodipine maintained both diastolic and syst olic pressures below tbe base line levels at every hour during the 24- hour observation period. Nine of 10 evaluable patients (90%) on amlodi pine responded vs only 1 of 5 patients (20%) on placebo. The decrease in blood pressure for the amlodipine patients was not accompanied by a significant increase in pulse rate. Amlodipine was well tolerated; po ssibly drug-related side effects of intermittent headache and nocturia were experienced by 1 patient each; the latter had been present durin g the placebo run-in phase. Amlodipine is effective, well tolerated, a nd may be administered once daily for effective 24-hour blood pressure control.