The nonsteroidal anti-inflammatory drugs flurbiprofen and ibuprofen were modified in an attempt to alter the kinetics of inhibitor binding by COX-1. Contrary to prior predictions, a halogen substituent is not sufficient to confer slow tight-binding behavior. Conversion of the carboxylate moiety of flurbiprofen to an ester or amide abolishes slow tight-binding behavior, regardless of halogenation state.
