Identification and pharmacokinetics of cyclophosphamide (NSC-26271) metabolites in vivo.

The existence of the cyclophosphamide (CP) metabolites, 4-hydroxycyclophosphamide and aldophosphamide, in vivo after application of CP to mice and rats has been demonstrated. The metabolite pattern in the serum and urine of rats at different times after CP application was determined. For this purpose, thin-layer chromatograpic procedure was developed which allows separation of the metabolites without decomposition. Because considerable amounts of radioactivity are bound to serum proteins after 3H-CP application, protein binding studies with CP and CP metabolites were carried out. It was found that 4-hydroxycyclophosphamide is bound to thiol groups of bovine serum albumin yielding a rather stable product which could be isolated by column chromatography on Sephadex.