Letter by Fisher and Johns Regarding Article, “Variable Platelet Response to Aspirin and Clopidogrel in Atherothrombotic Disease”
To the Editor:
We read with great interest the recent review by Maree and Fitzgerald.1 They should be congratulated for their informative summary of a quickly evolving area. However, we are concerned about their comments in the Aspirin Formulation section of the article. In this section, they cover the various formulations of aspirin and review findings from studies performed by their group. The authors caution the reader to be wary of enteric-coated formulations of aspirin because they have been observed to be less effective than plain aspirin tablets. It is unfortunate and concerning that they have chosen to generalize their observation instead of limiting their warnings to the specific products analyzed. All aspirin products and manufacturing practices are not the same. The original publication by the same authors demonstrated this in that they showed significant differences not only between plain aspirin and enteric-coated aspirin but also between different enteric-coated products over the same aspirin dose.2 A recent clinical comparison of a leading enteric-coated aspirin tablet and a plain aspirin tablet demonstrated no difference in the levels of platelet inhibition.3 General statements such as those regarding the efficacy of enteric-coated aspirin are frequently picked up by the lay media and may have a significant impact. There is already an underuse of aspirin in appropriate populations, and suggestions that enteric-coated formulations may not be effective could only negatively affect this situation.
Both authors are employees of Bayer HealthCare.
Maree AO, Fitzgerald DJ. Variable platelet response to aspirin and clopidogrel in atherothrombotic disease. Circulation. 2007; 115: 2196–2207.
Cox D, Maree AO, Dooley M, Conroy R, Byrne MF, Fitzgerald DJ. Effect of enteric coating on antiplatelet activity of low dose aspirin in healthy volunteers. Stroke. 2006; 37: 2153–2158.
Karha J, Rajagopal V, Kottke-Marchant K, Bhatt DL. Lack of effect of enteric coating on aspirin-induced inhibition of platelet aggregation in healthy volunteers. Am Heart J. 2006; 151: 976.e7–e11.