In Vivo: In vivo, CP-96021 inhibits iv LTD4- and iv PAF-induced bronchoconstriction in guinea pigs with ED50s of 0.46 and 0.16 mg/kg p.o. respectively. CP-96021 effectively blocks the combined airway obstructive effects of endogenously released PAF and LTD4 stimulated by aerosolized antigen challenge in guinea pigs with an ED50s of 1.8 mg/kg p.o.