Diclofenac-d₄contains four deuterium atoms on the benzene ring. It is intended for use as an internal standard for the quantification of diclofenac by GC- or LC-mass spectrometry. Diclofenac is a non-selective COX inhibitor.^1,2,3It inhibits human COX-1 and -2 with IC₅₀values of 0.9-2.7 and 1.5-20 µM, respectively.^1,2Diclofenac inhibits ovine COX-1 and -2 with IC₅₀values of 60 and 220 nM, respectively.³

1.Laneuville, O., Breuer, D.K., DeWitt, D.L., et al.Differential inhibition of human prostaglandin endoperoxide H synthases-1 and -2 by nonsteroidal anti-inflammatory drugsJ. Pharmacol. Exp. Ther.271(2)927-934(1994) 2.Barnett, J., Chow, J., Ives, D., et al.Purification, characterization and selective inhibition of human prostaglandin G/H synthase 1 and 2 expressed in the baculovirus systemBiochim Biophys. Acta.1209(1)130-139(1994) 3.Johnson, J.L., Wimsatt, J., Buckel, S.D., et al.Purification and characterization of prostaglandin H synthase-2 from sheep placental cotyledonsArch. Biochem. Biophys.324(1)26-34(1995)