Notes: 4-Biphenylacetic acid is a non-steroidal anti-inflammatory drug (NSAID) and an active metabolite of the prodrug fenbufen (Item No. 28851).{52083} It inhibits prostaglandin E2 (PGE2; Item No. 14010) synthesis in a cell-free assay (IC50 = 3.2 µM). In vivo, 4-biphenylacetic acid (2 mg/kg) suppresses UV-induced erythema in guinea pigs. 4-Biphenylacetic acid (16 mg/kg) reduces inflammation in a rat model of adjuvant-induced arthritis. It decreases phenylquinone-induced writhing in mice (ED50 = 9.9 mg/kg).{52084}