Cyclophosphamide Injection 500 mg Single-Dose Vial (RX)Cyclophosphamide Injection 500 mg Alkylating Chemotherapy Immunosuppressant Cyclophosphamide is a potent alkylating agent (nitrogen mustard derivative) used in oncology and severe autoimmune diseases. The 500 mg injection is supplied as a sterile lyophilized powder (200 mg mL concentrate when reconstituted). It is a prodrug that requires activation in the liver: cytochrome P450 enzymes convert cyclophosphamide to active metabolites (primarily 4