Naproxen‐aspirin interactions in man

Abstract

Pharmacokinetic interactions between aspirin and other nonsteroidal anti‐inflammatory drugs, including naproxen, have been demonstrated in experimental animals. This study shows that simultaneous oral administration of aspirin and naproxen in man results in a small but statistically significant lowering of plasma levels of naproxen. This effect is not mediated by competition for drug absorption but is associated with enhanced renal clearance of naproxen or its metabolites. Salicylates displace naproxen from binding sites on plasma proteins, a phenomenon that may be responsible for the accelerated clearance. The clinical significance, if any, Of these findings is not yet established, but the relatively small magnitude of the effects noted suggests that the likelihood of a meaningful interaction is small.