Carboxycyclophosphamide is an inactive metabolite of the cytotoxic antineoplastic drug cyclophosphamide. In the metabolic pathway of cyclophosphamide inactivation it first metabolizes to 4-hydroxycyclophosphamide, then partially tautomerizes into aldophosphamide. Aldophosphamide then, in turn, is oxidized into carboxycyclophosphamide by the enzyme ALDH (aldehyde dehydrogenase).
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