GAS-CHROMATOGRAPHIC (GC) METHOD FOR THE DETERMINATION OF SCH-44643, AN ORALLY-ACTIVE ANTAGONIST OF PLATELET-ACTIVATING-FACTOR IN RAT PLASMA

A gas chromatographic (GC) assay for the determination of SCH 44643, a n orally active antagonist of responses to both histamine and PAF was developed and validated for rat plasma. The method involved organic so lvent extraction followed by solid phase extraction on aminopropyl col umn. The separation was on a capillary column (DB-17) with quantitatio n by a nitrogen-phosphorus detection. The method was sensitive with a limit of quantitation of 5 ng mL(-1). There was a good linear relation ship between the peak height ratio (SCH 44643/internal standard) and S CH 44643 concentration in the range 5 to 200 ng mL(-1). The method was precise with a coefficient of variation ranging from 1.8 to 3.0 % and accurate with a bias ranging from 0 to 5.8 %. Moreover, SCH 44643 was stable in rat plasma after being subjected to three freeze-thaw cycle s. The assay was shown to be sensitive, specific, accurate and precise , and suitable for use in pharmacokinetic or toxicokinetic studies.