Hemorrhagic cystitis is a known side effect of which chemotherapy agent?

• A. Doxorubicin
• B. Cisplatin
• C. Cyclophosphamide
• D. Methotrexate

Answer: (C)

Hemorrhagic cystitis happens when a drug metabolite irritates the bladder lining. Cyclophosphamide is metabolized in the body to acrolein, which is excreted in the urine and directly irritates the bladder mucosa, leading to inflammation, bleeding, and painful urination. Prevention hinges on mesna, a compound that binds acrolein in the urine and neutralizes it, along with good hydration to dilute the urine; sometimes bladder irrigation is used if symptoms occur. Other agents listed have different toxicity profiles—for example, doxorubicin is known for cardiotoxicity, cisplatin for nephrotoxicity, and methotrexate for mucositis and renal effects—so they’re not typical culprits for this specific side effect. Ifosfamide can also cause hemorrhagic cystitis via the same acrolein mechanism, which is why similar preventive measures are used with that drug.