Recent studies showed that low dose aspirin exerts a significant administration time-dependent effect on blood pressure in previously untreated hypertensive patients. However, this effect has not been confirmed in patients taking low-dose aspirin in combination with antihypertensive medications. A multi-center, double-blind randomized, cross-over, active-control, comparative clinical study will be conducted to evaluate the influence of aspirin on blood pressure in well-controlled hypertensive patients who receive low dose aspirin at different times of the day.~Approximately 192 patients will be enrolled over 4 months in 8 centers nationwide.~After placebo run-in period, all subjects will be randomized into one of the following 3 groups.~Group I & II will take low dose aspirin for treatment period (for first and second 12 weeks)on awakening or before bed time. Group III will take placebo for treatment period.~After first 12 weeks' treatment period, the subjects will be informed whether she/he belongs to Group III. This will be done without breaking the double blinding in the other 2 groups.~The primary objective will be the evaluation of the influence of aspirin on blood pressure in well-controlled hypertensive patients who receive low dose aspirin at different times of the day.~The secondary objectives will be 1) comparison of the administration time-dependent effects of low dose aspirin on blood pressure between dipper and non-dipper patients and 2) the evaluation of the effects of low dose aspirin in Korean hypertensive patients.~A sub-study will be conducted in 3 centers to evaluate the effect of aspirin on endothelial function in patients with well-controlled hypertension.
The purpose of this study is to evaluate the influence of aspirin on blood pressure in well-controlled hypertensive patients who receive low dose aspirin at different times of the day