A direct radioimmunoassay for E5880, 1-ethyl-2-[[N-(2-methoxybenzoyl)-N-[[(2R)-2-methoxy-3-[[[4- [(octadecylcarbamoyl)- oxy]piperidino]carbonyl]oxy]propoxy]carbonyl]amino]methyl] pyridinium chloride, a novel analogue-type antagonist of plateletactivatingfactor (PAF), was developed. In this procedure, [3H]E5880 was used as the radioligand, and the antiserum was obtained from rabbits immunized with
A glycerin derivative having the following formula (I) or (I') and a pharmacologically acceptable salt thereof are useful to treat diseases caused by the platelet activating factor. ##STR1##