QUANTITATION BY GAS CHROMATOGRAPHY CHEMICAL IONIZATION MASS-SPECTROMETRY OF CYCLOPHOSPHAMIDE, PHOSPHORAMIDE MUSTARD, AND NORNITROGEN MUSTARD IN PLASMA AND URINE OF PATIENTS RECEIVING CYCLOPHOSPHAMIDE THERAPY

Abstract

Unambiguous and sensitive methods based on gas chromatography-chemical ionization mass spectrometry were developed to quantitate cyclophosphamide and 2 alkylating and cytotoxic metabolites, phosphoramide mustard and nornitrogen mustard. The levels of these materials were determined in the plasma and urine of 5 patients receiving cyclophosphamide, 60 or 75 mg/kg i.v. Peak plasma levels of phosphoramide mustard of 50-100 nmol/ml were found 3 h after cyclophosphamide administration. Variable levels of nornitrogen mustard were found in the plasma. This product may be arising in part from the decomposition of other metabolites during sample storage and preparation.