Hemorrhagic cystitis is caused by: September 2005, March 2013
**Core Concept**
Hemorrhagic cystitis is a condition characterized by bleeding from the bladder, often resulting from chemical or radiation injury to the urothelial lining. The condition is commonly associated with the use of certain medications or exposure to specific substances that can cause direct damage to the bladder mucosa.
**Why the Correct Answer is Right**
The correct answer is cyclophosphamide, a chemotherapeutic agent that belongs to the oxazaphosphorine class. Cyclophosphamide is metabolized by the liver enzyme cytochrome P450 to form its active metabolite, acrolein, which is responsible for the toxic effects on the bladder mucosa, leading to hemorrhagic cystitis. The direct contact of acrolein with the bladder lining causes urothelial damage, resulting in bleeding.
**Why Each Wrong Option is Incorrect**
**Option A:** Cisplatin is a chemotherapeutic agent that can cause nephrotoxicity and ototoxicity but is not primarily associated with hemorrhagic cystitis.
**Option B:** Ifosfamide is another chemotherapeutic agent that can cause hemorrhagic cystitis, but it is not the most commonly implicated agent.
**Option C:** Radiation therapy can cause hemorrhagic cystitis, but it is not the correct answer in this context.
**Clinical Pearl / High-Yield Fact**
Cyclophosphamide-induced hemorrhagic cystitis can be prevented or reduced with the use of mesna, a protective agent that binds to acrolein and reduces its toxic effects on the bladder mucosa.
**Correct Answer: A. Cyclophosphamide**