The analgesic and anti-inflammatory profile of (±)-5-benzoyl-1,2-dihydro-3H-pyrrolo[1,2a]pyrrole-1-carboxylic acid (RS-37619)

Abstract

RS-37619 showed highly potent analgesic activity when given p.o. in tests utilizing underlying inflammation. It inhibited phenylquinone-induced writhing in the mouse and rat (350 and 180×aspirin respectively) and the pain induced by flexing the adjuvant-inflamed rat paw (∼ 800×aspirin). The agent increased the pain threshold of compressed yeast-inflamed rat paws (3-10 ×naproxen). RS-37619 did not increase the pain threshold of the noninflamed paw and was inactive in the mouse hot plate test; therefore it is probably not a centrally acting or morphinelike agent. RS-37619 was also highly active p.o. in rat models of acute and chronic inflammation. It inhibited carrageenan-induced paw edema (36×phenylbutazone), cotton pellet-induced granuloma (≤1×indomethacin) and in an 18-day test, prevented the development of adjuvant-induced arthritis (∼2×naproxen). RS-37619 exhibited antiphlogistic activity in adrenalectomized rats. It did not have corticosteroid activity. When given p.o., RS-37619 lowered yeast-induced pyrexia (20×aspirin). Gastro-intestinal irritation was seen in the rat with doses ≥6.4 mg/kg/day p.o. The agent elicited mild CNS and cardiovascular activity only at doses far in excess of those required for analgesic and anti-inflammatory activity. © 1982 Birkhäuser Verlag.