Is there evidence to support the use of enteric coated (EC) aspirin to reduce gastrointestinal side effects in cardiovascular patients?

Medicines Q&A: Is there Evidence to Support the use of Enteric Coated (EC) Aspirin to Reduce Gastrointestinal Side Effects in Cardiovascular Patients?

The enteric coated (EC) formulation was developed and marketed in an effort to reduce GI adverse effects associated with aspirin. This Medicines Q&A prepared by NHS Specialist Pharmacy Service reviews the evidence on the use of EC aspirin to prevent GI damage, and the effect of the enteric coating on anti-platelet effect of aspirin.


  • Low dose EC aspirin tablets were developed and marketed in an effort to reduce the incidence of GI side effects in patients using it for prevention of CVD.
  • Enteric coating prevents aspirin from dissolving in the stomach, which is instead released in the higher pH of the duodenum, theoretically protecting the gastric mucosa from local irritation.
  • The available evidence is not robust enough to support a gastro-protective role of EC aspirin compared to standard release (plain) aspirin.
  • There is speculation that enteric coating reduces the anti-platelet effect of aspirin, and thus its efficacy in the prevention of cardiovascular events. The available evidence for this is however conflicting. There is a theory of pseudoresistance reflecting delayed and reduced drug absorption with EC aspirin over normal plain aspirin. Additionally the studies employed the use of surrogate rather than clinical outcome measures to evaluate the anti-platelet efficacy of standard and EC formulations and the significance of these findings in practice is thus not known