Determination of the platelet activating factor antagonist 6-(2- chlorophenyl)-9-[(4-methoxyphenyl)thiocarbamoyl]-1-methyl-7,8,9,10- tetrahydro-4H-pyrido[4',3'-4,5]-thieno[3,2-f][1,2,4]triazolo[4, 3-a][1,4] diazepine in human plasma by liquid chromatography-thermospray mass spectrometry.

A sensitive and specific method for the determination of the platelet activating factor (PAF) antagonist 6-(2-chlorophenyl)-9-[(4-methoxyphenyl)-thiocarbamoyl]-1-methyl-7,8,9,10- tetrahydro-4H-pyrido[4',3'-4,5]thieno-[3,2-f][1, 2, 4]triazolo [4, 3-a][1, 4] diazepine (I) in human plasma is described. The target molecule was analyzed by high-performance liquid chromatography (HPLC) coupled to mass spectrometry (MS) after extraction by ion-exchange chromatography. HPLC was carried out using a C18 column and the coupling to the MS was done by a thermospray (TSP) interface working in the direct ion-evaporation ionization mode in presence of 0.1 M ammonium acetate. Selected-ion monitoring (SIM) was carried out for the ion m/z 370 and its [M + 2]+ isotopic peak. Evaluation of the intensity matching of such ions has been used in the validation results. The method gives good accuracy and precision over the concentration range 1-200 ng/ml in human plasma.