What is the drug of choice (DOC) for preventing hemorrhagic cystitis caused by cyclophosphamide?

The drug of choice for preventing hemorrhagic cystitis caused by cyclophosphamide is Mesna. This medication is a sulfhydryl compound that works by binding to the toxic metabolites of cyclophosphamide, specifically acrolein, which can irritate the bladder and lead to hemorrhagic cystitis. Mesna helps to neutralize these harmful metabolites and provides a protective effect on the bladder lining.

Hemorrhagic cystitis is a known side effect of cyclophosphamide due to the generation of acrolein, which directly irritates the bladder epithelium. By administering Mesna concurrently with cyclophosphamide, the incidence and severity of this side effect can be significantly reduced.

Other options listed do not serve this specific purpose. Acetaminophen is mainly used for pain and fever relief, N-acetylcysteine is an antidote for acetaminophen overdose and has other uses like mucolytic properties, and ciprofloxacin is an antibiotic that treats bacterial infections. None of these would prevent the cystitis induced by cyclophosphamide.