More than half of diabetes patients who experienced aspirin resistance with once-daily dosing overcame it when aspirin was administered in 2 daily doses.
The recommendation to prescribe a cardioprotective dose of aspirin for all diabetes patients who can tolerate it is ubiquitous in cardiac care guidelines. Complications after acute coronary syndrome (ACS) and percutaneous coronary intervention occur frequently even if the diabetes patient is adherent to prescribed aspirin. Aspirin’s efficacy in the diabetes population seems to be lower than it is in other populations, and simply increasing the dose has not resulted in improved morbidity or mortality.
The results of a study
published in the October 2012 issue of the American Heart Journal
indicate that aspirin efficacy decreases over 24 hours, particularly in patients with diabetes, patients with elevated inflammatory markers, and smokers. This suggests that a single daily aspirin may not provide 24-hour coverage to prevent ACS or other cardiac decline.
The researchers prospectively compared the biologic efficacy of aspirin when given once versus twice daily in a population of diabetes patients with previous coronary artery disease. The researchers enrolled 92 consecutive diabetes patients with at least 1 criteria of time-dependent aspirin efficacy, elevated high-sensitivity C-reactive protein (hs-CRP), fibrinogen, platelet count, or active smoking. They randomized patients to 150 mg aspirin daily given in the morning or 75 mg in the morning and 75 mg in the evening in a crossover design. The main outcome was platelet reactivity at trough level before the morning aspirin dose.
The researchers found aspirin resistance in 42% (n=39) of patients on once-daily dosing and in 17% (n=16) of patients on twice-daily dosing. After crossover to twice-daily dosing, 62% of the diabetes patients resistant to aspirin on once-daily dosing overcame resistance. Among the 16 resistant on twice-daily dosing who switched to once-daily dosing, only 1 patient overcame resistance.
Dividing the aspirin dose for diabetes patients who are at high risk of time-dependent aspirin resistance can significantly decrease loss of efficacy.
Ms. Wick is a visiting professor at the University of Connecticut School of Pharmacy and a freelance writer from Virginia.