A comparative study of the antiinflammatory activity of fentiazac and its major metabolite, p-hydroxy fentiazac.

Wy-25,110, the p-OH metabolite of fentiazac was approximately 100 times less potent than fentiazac after oral administration in rat carrageenan edema and 100-130 times less potent as an inhibitor of prostaglandin synthesis by mouse peritoneal macrophages. In addition, Wy-25,110 was one twelfth as active as fentiazac against immunologic-induced inflammation on day 16 in rat adjuvant arthritis. Wy-25,110 was also much less potent than fentiazac when administered intravenously, suggesting that inadequate oral absorption does not account for its lack of potency. Thus it seems unlikely that the p-OH metabolite contributes greatly to the antiinflammatory properties of fentiazac.