The effect of amlodipine on ambulatory blood pressure in hypertensive patients

Certain high-risk populations, such as diabetics and blacks, have sustained elevation in blood pressure and heart rate throughout the day and night, with blunting of the usual diurnal variability pattern. This may contribute to their higher incidence of left ventricular hypertrophy (blacks) and cardiovascular complications (diabetics). Hypertensives who maintain a diurnal pattern of blood pressure variation still exhibit higher daytime and nocturnal blood pressure levels than normotensives. Thus, to achieve maximum effectiveness in treating hypertension, 24-hour control of blood pressure is necessary. Antihypertensive agents 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-controlled single-site study. Patients with mild-to-moderate essential hypertension 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 followed by a 4-week double-blind phase. Ambulatory monitoring of blood pressure was carried out for 24 hours at the end of each 4-week phase. Patients receiving amlodipine had significantly lower blood pressure compared 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-hour postdose measurement and the mean blood pressure over the 24-hour interval as measured by ambulatory recordings. The mean hourly ambulatory recordings showed that amlodipine maintained both diastolic and systolic pressures below the baseline levels at every hour during the 24-hour observation period. Nine of 10 evaluable patients (90%) on amlodipine 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; possibly drug-related side effects of intermittent headache and nocturia were experienced by 1 patient each; the latter had been present during the placebo run-in phase. Amlodipine is effective, well tolerated, and may be administered once daily for effective 24-hour blood pressure control.