A double-blind evaluation of the effect of amlodipine on ambulatory blood pressure in hypertensive patients.

Amlodipine is a new long-acting calcium antagonist that has a long half-life and appears to be suitable for once-daily administration. A double-blind, randomized, parallel, placebo-controlled study was conducted to evaluate the effect of amlodipine on ambulatory blood pressures in hypertensive patients. The study consisted of a 4-week single-blind placebo run-in phase, followed by 4 weeks of double-blind therapy. Ambulatory blood pressure was measured for 24 h at the end of the placebo run-in phase and after double-blind therapy. Sixteen patients were randomized to receive either amlodipine 5 mg or placebo in a 2:1 ratio. Amlodipine 5 mg daily significantly reduced supine and standing blood pressure 24 h postdose. Ambulatory blood pressure recordings revealed adequate blood pressure control throughout the 24-h dosing interval. Amlodipine was well tolerated and only two patients reported side effects--neither was withdrawn from therapy. No treatment-related abnormalities were noted. It was concluded that amlodipine 5 mg daily was effective antihypertensive therapy throughout the 24-h dosing period in the patients studied, and it was well tolerated.