Welcome to Cytoxan (cyclophosphamide), one of the most versatile (albeit toxic) medications in the nephrology world. Its mechanism of action is as an alkylating agent; it induced alkylation of DNA in actively proliferating cells, which explains its use as a chemotherapeutic as well as an immunomodulatory agent. Its use in renal disease includes lupus nephritis, nephrotic syndrome of several types, ANCA-associated vasculitides, and many others.
However, it has several side effects to be aware of. Some of the main ones are listed here:
1. Hemorrhagic Cystitis: one of the metabolites of Cytoxan, acrolein, causes bladder irritation and can result in hemorrhagic. The risk of this complication can be limited by the concomitant use of mesa, which accumulates in the collecting system and binds/inactivates acrolein.
2. Infertility: this can occur in both men & women; men are encouraged to do sperm-banking before receiving Cytoxan while women may be offered Lupron therapy in an attempt to chemically suppress the ovulatory cycle for the time they are on the medication.
3. Alopecia: like many of the side effects associated with Cytoxan, this one is rare at the doses given for renal disease, which are typically much smaller than those given for oncologic disease.
4. Increased Risk of Infection/Leukopenia.
6. Increased risk of Malignancies in the future: especially bladder cancer.
7. SIADH: rare but possible.