Intra-arterial monitoring of the antihypertensive effects of once-daily amlodipine.

Amlodipine is a dihydropyridine calcium antagonist with a long elimination half life making it suitable for once-daily dosing. This study used sphygmomanometric and intra-arterial ambulatory blood pressure (BP) monitoring to confirm the antihypertensive effect of a once-daily dose of amlodipine over the dosing interval. After a 2-week single-blind placebo run in, amlodipine was administered to 11 patients at a starting dose of 5 mg daily for 2 weeks increasing to 10 mg daily for a further 4 weeks if diastolic blood pressure (DBP) measured sphygmomanometrically was not < 90 mmHg or decreased by > 10 mmHg from baseline values. Intra-arterial blood pressure recordings for 24-hour periods were made at the end of the placebo run in and on completion of the active treatment phase. The effects of isometric and dynamic exercise and head-up tilting (60 degrees) on BP and heart rate were measured during ambulatory monitoring. Mean supine cuff BP was 169/104 mmHg (n = 11) at the end of the placebo treatment period and was reduced to 153/95 mmHg (n = 11) after 2 weeks of amlodipine treatment and 146/92 mmHg (n = 11) after 6 weeks of amlodipine treatment. There was no significant change in heart rate. Intra-arterial ambulatory monitoring showed that BP was controlled for the whole dosing interval with once-daily doses of amlodipine. The normal circadian pattern of BP changes was not altered. BP was reduced by amlodipine during exercise and physiological tests, but there was no postural hypotension and the BP and heart rate responses to exercise were not blunted.(ABSTRACT TRUNCATED AT 250 WORDS)