Differential effects of morning or evening dosing of amlodipine on circadian blood pressure and heart rate.
OBJECTIVE
To compare the effects of morning and evening dosing of amlodipine on both circadian blood pressure (BP) and heart rate (HR) in mild-to-moderate essential hypertension.


METHODS
A perspective, double-blind, randomized, crossover design with dose titration.


METHODS
Sixty-two patients recruited in the study were aged 21-77 years and had mild-to-moderate essential hypertension. At the end of a 2-week single-blind, placebo run-in period, eligible patients were randomly assigned to morning (7 AM) and evening (9 PM) amlodipine treatment. The initial dose was 5 mg. After 2 weeks of double-blind therapy, patients with a seated diastolic blood pressure > or =90 mm Hg had their doses titrated upward to 10 mg, while the other patients remained on their original 5 mg doses for another 4 weeks period, than crossover to the alternate dosing regimen for 6 additional weeks. The 24-h ambulatory monitoring was performed at baseline and at 6 and 12 weeks after randomization.


RESULTS
24-h diastolic BP load (11.0 +/- 17.5% vs. 6.5 +/- 9.1%, P < 0.05) and night-time BP load (28.5 +/- 31.4%/17.7 +/- 28.2% vs. 20.0 +/- 27.9%/9.2 +/- 17.8%, P < 0.05/0.05) were significantly greater with evening dosing compared with morning dosing. Nocturnal fall of BP was greater with morning dosing than with evening dosing (9.8 +/- 6.7/7.4 +/- 5.3 vs. 6.7 +/- 6.6/5.4 +/- 5.4 mm Hg, P < 0.01/0.05). Percentage of nocturnal BP fall was greater with morning dosing versus with evening dosing (7.9 +/- 5.3%/9.6 +/- 6.8% vs. 5.4 +/- 7.0%/7.0 +/- 6.9%, P < 0.01/0.05).


CONCLUSIONS
Morning administered amlodipine had a better effect on the circadian BP compared with evening administrated amlodipine in mild-to-moderate essential hypertension.
Qiu
Yuan-Gang
YG
Department of Cardiology, The First Affiliated Hospital, Zhejiang University, College of Medicine, Hangzhou, P.R. China. qiuyuangang@yahoo.com.cn
Chen
Jun-Zhu
JZ
Zhu
Jian-Hua
JH
Yao
Xue-Yan
XY
D000328:Adult; D000368:Aged; D017311:Amlodipine / Q000008:administration & dosage / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects*; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000627:therapeutic use*; D002940:Circadian Rhythm; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged
D002121:Calcium Channel Blockers; D017311:Amlodipine