INFLUENCE OF ASPIRIN USAGE ON BLOOD-PRESSURE - DOSE AND ADMINISTRATION-TIME DEPENDENCIES

This study investigates the possible effects of acetylsalicylic acid ( ASA; aspirin) on systolic (S) and diastolic (D) blood pressure (BP) in healthy and mildly hypertensive subjects receiving ASA at different t imes according to their rest-activity cycle. A double-blind, randomize d, controlled trial was conducted in 73 healthy young adult volunteers and 18 previously untreated subjects with mild hypertension. The BP o f each subject was automatically monitored every 30 minutes for 48h be fore the trial and at the end of a one-week course of placebo and a on e-week course of ASA. Healthy volunteers were randomly assigned to one of six groups, defined according to the dose of ASA (either 500 mg/da y, the usual commercial dose; or 100 mg/day) and timing of ASA and pla cebo (within 2h after awakening, Time 1; 7h to 9h after awakening, Tim e 2; or within 2h of bedtime, Time 3). Subjects with mild hypertension received the low dose of 100 mg/day ASA, as well as one week of place bo, and were randomly assigned to one of the same three groups defined above according to the time of treatment. A small (similar to 2 mmHg in the 24h mean of SBP), but statistically significant, BP reduction w as found when 500 mg/day ASA was given to healthy volunteers at Time 2 . With 100 mg/day, the effect of ASA in healthy subjects was comparabl e to the BP reduction found with the higher dose for Time 2; there was again no effect on BP at Time 1, but we found a statistically signifi cant effect at Time 3 (2.3 mmHg reduction in the 24h mean of SBP), lar ger than for Time 2, For hypertensive patients, the BP reduction was a gain statistically significant for Time 2 and, to a greater extent, fo r Time 3 (similar to 4.5 mmHg for both SBP and DBP); all patients in t hese two groups showed a BP reduction after one week of ASA. The effec t was about three times as large as the BP reduction obtained in healt hy subjects treated with 100 mg/day ASA. Results indicate a statistica lly significant time- and dose-dependent effect of ASB on BP. In any m eta-analysis of ASB effects, inquiries about the time when subjects to ok the drug are indicated and may account for discrepancies in the lit erature. Moreover, the influence of BSA on BP demonstrated here indica tes the need to identify and control for ASA effects in patients using ASA before or during their participation in antihypertension medicati on trials.