Enteric coating can affect aspirin‘s inhibition of platelet aggregation, according to a study in Circulation.

Researchers used three assays — platelet aggregation, serum thromboxane formation, and urinary excretion of a thromboxane metabolite — to test response to an oral dose of 325-mg immediate-release or enteric-coated aspirin in 400 healthy volunteers (median age, 26). The study was partly funded by Bayer HealthCare.

No participant showed resistance to the immediate-release formulation. Up to 49% showed resistance to enteric-coated aspirin, but most were not resistant upon retesting.

The authors conclude that “we failed to find a single case of true drug resistance” and that their findings show “inconsistent platelet inhibition” after ingestion of enteric-coated aspirin.

Source: Circulation