Valeroyl salicylate is a selective, irreversible inhibitor of COX-1. The IC50 values for ovine COX-1 and -2 are 0.8 mM and 15 mM, respectively.{1364} The half-lives for inactivation of human recombinant and ovine COX-1 in the presence of 500 μM valeroyl salicylate are 12 and 45 minutes, respectively.{1284,1364}