Administration Time-dependent Antihypertensive Effects of Low Dose Aspirin in Well-controlled Hypertensive Patients

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.