FPL 52791 Na salt (I-Na) [37456-31-8] inhibited the passive cutaneous anaphylaxis reaction in rats with ED50s of 0.1 and 4.2 mg/kg when given i.v. and orally resp.In anesthetized rats sensitized with rat anticonalbumin/B. pertussis serum, I-Na given 1 min before antigen challenge with ovalbumin protected against anaphylactic bronchoconstriction with an ED50 of 0.3 mg/kg.In adjuvant-induced arthritis in rats, I-Na (100 mg/kg, orally) given from days 10 to 16 after initiation of the reaction inhibited secondary swelling of the injected foot by 57.4%.The antiinflammatory effect of I was the result of prostaglandin synthetase [9055-65-6] inhibition rather than adrenal stimulation.I-Na had analgesic activity (ED50 of 48 mg/kg, orally) in the AcOH-induced writhing test in mice, and had antipyretic activity at 30-100 mg/kg.In man, I-Na (50-400 mg) reduced plasma and increased urine urate [69-93-2] concentrations