Aspirin is commonly used for the secondary prevention of atherosclerotic cardiovascular disease (ASCVD). Enteric coating, also known as “safety coating,” is believed to reduce gastrointestinal bleeding associated with aspirin use. However, the effectiveness and safety of enteric-coated aspirin compared to uncoated aspirin remain uncertain. In a recent study called ADAPTABLE, researchers aimed to determine the impact of enteric coating on the incidence of cardiovascular events and bleeding events in individuals with ASCVD.
The ADAPTABLE trial found that there was no significant difference in the combined incidence of myocardial infarction, stroke, or all-cause death between enteric-coated and uncoated aspirin users. The study, which followed participants for a median of 26.2 months, reported an adjusted hazard ratio of 0.94 (95% CI 0.80-1.09), indicating no superiority of enteric-coated aspirin in preventing cardiovascular events. Additionally, there was no significant difference in major bleeding events between the two groups (adjusted HR 0.82, 95% CI 0.49-1.37).
While prior pharmacodynamic studies have shown that enteric coating delays the dissolution and absorption of aspirin in the small intestine, the clinical outcomes of enteric-coated aspirin are still inconclusive. The ADAPTABLE trial suggests that the presence of enteric coating does not have a significant impact on the effectiveness or safety of aspirin for secondary prevention of ASCVD. However, it is important to note that the study did not assess minor gastrointestinal bleeding or other bleeding events.
The ADAPTABLE trial had a few limitations. Firstly, the participants’ adherence to their reported aspirin formulation and the potential switching of formulations during the trial were not tracked. This lack of adherence and potential formulation changes may have influenced the outcomes. Secondly, the trial did not investigate whether coadministration of acid-reducing medication with enteric-coated aspirin influenced ischemic or bleeding rates.
The findings of the ADAPTABLE trial call into question the widely held belief that enteric-coated aspirin is safer than uncoated aspirin. More research is needed to confirm whether enteric-coated aspirin formulations or newer formulations can improve ischemic and bleeding outcomes in patients with ASCVD. Additionally, future studies should investigate the impact of enteric coating on minor gastrointestinal bleeding and explore the potential benefits of combination therapy with acid-reducing medications.
The ADAPTABLE trial found that enteric coating did not enhance the effectiveness or safety of aspirin for secondary prevention of ASCVD. The study highlights the need for further discussion and research on the appropriate formulation and dose of aspirin for individual patients. Clinicians should consider the lack of evidence supporting the superiority of enteric-coated aspirin and make informed decisions in prescribing aspirin for cardiovascular disease prevention.
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