Phenylbutazone is a non-steroidal anti-inflammatory drug and an inhibitor of the peroxidase activity of COX (IC50 = ~100 ?M in the presence of hydrogen peroxide).1 It also inhibits prostaglandin I synthase (IC50 = ~25 ?M in the presence of hydrogen peroxide). Phenylbutazone (2 mg/kg) reduces increases in type II collagen levels in the inflamed joints of an equine model of LPS-induced acute synovitis.2 Formulations containing phenylbutazone have been used in the treatment of lameness in horses.
1.Reed, G.A., Griffin, I.O., and Eling, T.E.Inactivation of prostaglandin H synthase and prostacyclin synthase by phenylbutazone. Requirement for peroxidative metabolismMol. Pharmacol.27(1)109-114(1985) 2.de Grauw, J.C., van Loon, J.P.A.M., van de Lest, C.H.A., et al.In vivo effects of phenylbutazone on inflammation and cartilage-derived biomarkers in equine joints with acute synovitisVet. J.201(1)51-56(2014)