6a , 7 , 10 , 10a - tetrahydro - 6 , 6 - dimethyl - 9 - carboxyl - 3 - pentyl - 6 - h - dibenzo pyran - 1 - ol is a potent antagonist to endogenous platelet activating factor . paf is a factor in many of the pathological manifestations of disease , allergy or injury , such as inflammation , thrombosis and anaphylaxis . the actions of paf can be inhibited in vivo by the present composition , thereby providing a safe and effective treatment for paf - induced disorders .