A child is undergoing remission induction therapy to treat leukemia. Allopurinol is included in the regimen. The main reason for administering allopurinol as part of the client’s chemotherapy regimen is to:
A. Prevent uric acid from precipitating in the ureters
B. Enhance the production of uric acid to ensure adequate excretion of urine
C. Prevent metabolic breakdown of xanthine to uric acid
D. Ensure that the chemotherapy doesn’t adversely affect the bone marrow
Correct Answer: C. Prevent metabolic breakdown of xanthine to uric acid
The massive cell destruction resulting from chemotherapy may place the client at risk for developing renal calculi; adding allopurinol decreases this risk by preventing the breakdown of xanthine to uric acid. These clients can have increased uric acid levels due to release of uric acid from the dying cancer cells.
Option A: Allopurinol and oxypurinol both inhibit xanthine oxidase, an enzyme in the purine catabolism pathway that converts hypoxanthine to xanthine to uric acid. Allopurinol undergoes metabolism in the liver, where it transforms into its pharmacologically active metabolite, oxypurinol.
Option B: Urate production is accelerated by purine-rich diets, endogenous purine production, and high cell breakdown, and it is responsible for a minority of cases of hyperuricemia. Foods rich in purine include all meats but specifically organ meats (kidneys, liver, “sweet bread”), game meats, and some seafood (anchovies, herring, scallops).
Option D: Allopurinol doesn’t act in the manner described in this option. To prevent tumor lysis syndrome, allopurinol shall be initiated 2 to 3 days before starting chemotherapy and continued until 3 to 7 days after chemotherapy.