Prolonged antihypertensive effect of amlodipine: a prospective double-blind randomized study

Amlodipine is a calcium antagonist with a long elimination half-life (35 to 50 h) allowing a once daily dosing in the treatment of hypertension. This randomized, double-blind study was performed to assess the residual antihyp ertensive effect of amlodipine 5 mg O.D. 3 days after discontinuing therapy in previously well-controlled mild to moderate hypertensive patients. Bloo d pressure (BP) was evaluated by conventional (OBP) and by ambulatory blood pressure monitoring (ABPM). Amlodipine 5 mg OD administered during a 6-wee k period, significantly reduced both OBP and ABPM mean values (p < 0.05), w hereas no change in heart rate was observed. At the end of the active treat ment period, adequately controlled patients were randomized either to amlod ipine 5 mg OD (group A) or amlodipine for 12 days followed by a 3-day perio d on placebo. After this double-blind treatment phase, group P exhibited no significant increase in BP (assessed by OBP or ABPM) when compared to grou p A. In conclusion, the duration of action of amlodipine extends largely be yond the 24-h span, and when patients omit their treatment for 3 days BP do es not significantly increase.