Sensitive gas chromatographic determination of the cyclophosphamide metabolite 2-dechloroethylcyclophosphamide in human plasma

Cyclophosphamide (CF) is one of the most frequently used anticancer agents. It is a prodrug requiring activation before exerting cytotoxicity. CP is d eactivated to 2-dechloroethylcyclophosphamide (2-DCECP) with formation of a n equimolar amount of chloroacetaldehyde. The aim of this study was to deve lop and validate a sensitive and simple assay for 2-DCECP in plasma of pati ents treated with CP. Sample pre-treatment consisted of solid-phase extract ion of 500 mul of plasma over OASIS HLB (1 ml) cartridges with trofosfamide as internal standard. Separation and detection of underivatized 2-DCECP wa s performed with capillary gas chromatography with nitrogen/phosphorous sel ective detection. Extraction recovery of 2-DCECP exceeded 87%. No interfere nce from endogenous compounds, other metabolites of CP and frequently co-ad ministered drugs was detected. The assay was linear in the range of 5-5000 ng/ml in plasma. Accuracy, within-day and between-day precision were less t han 11% fur the complete concentration range. In plasma, 2-DCECP was stable for at least 1 month when kept at -70 degreesC. Analysis of samples from p atients treated with CP demonstrated the applicability of the assay. In con clusion, a sensitive and simple assay for 2-DCECP in plasma, which meets th e current requirements for bioanalytical assays, was developed. (C) 2001 El sevier Science B.V. All rights reserved.