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A 42-year-old male suddenly develops dysuria and frequency despite the absence of bacteriuria; microscopic hematuria is noted. Over the course of the next few days, gross hematuria is seen. The patient is being treated for non-Hodgkin's lymphoma with a nitrogen mustard-type antineoplastic agent. Which of the following agents could have been administered to prevent the onset of the patient's symptoms?
A. Allopurinol
B. Leucovorin
C. Mesna
D. Penicillamine
E. Sodium thiosulfate
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Explanation:
The correct answer is C. The patient is presenting with signs and symptoms of hemorrhagic cystitis. This condition is characterized by a sudden onset of dysuria and frequency in the absence of bacteriuria. In severe cases of cystitis, large segments of bladder mucosa may be shed and the patient can have prolonged periods of gross hematuria. Furthermore, there may be bladder obstruction secondary to the development of blood clots. This disorder is most often seen in patients taking ifosfamide and cyclophosphamide, both of which are nitrogen mustards. Hemorrhagic cystitis can be prevented in patients taking ifosfamide and cyclophosphamide by administering mesna. Mesna reacts chemically with the urotoxic metabolites produced when both agents are metabolized. Mesna is not effective for prophylaxis of other types of hemorrhagic cystitis.
Allopurinol (choice A) is an antigout agent used prophylactically to reduce the severity of hyperuricemia associated with both antineoplastic and radiation therapy.
Leucovorin (choice B) is primarily used to prevent or diminish toxicity associated with the use of antineoplastic folic acid antagonists, particularly methotrexate.
Penicillamine (choice D) is a chelating agent used to promote the renal excretion of excess copper in Wilson's disease. It is also used for lead poisoning and treatment of rheumatoid arthritis in patients who have failed to respond to conventional antirheumatic therapies.
Sodium thiosulfate (choice E) is an antidote for cyanide poisoning.
