A male patient is undergoing chemotherapy may also be given the drug allopurinol (Zyloprim, Aloprim). Allopurinol inhibits the synthesis of uric acid. Concomitant administration of allopurinol prevents:
A. Myelosuppression.
B. Gout and hyperuricemia.
C. Pancytopenia.
D. Cancer cell growth and replication.
Correct Answer: B. Gout and hyperuricemia.
Prevent uric acid nephropathy, uric acid lithiasis, and gout during cancer therapy since chemotherapy causes the rapid destruction of cancer cells leading to excessive purine catabolism and uric acid formation. Allopurinol can induce myelosuppression and pancytopenia.
Option A: The mechanism is a T-cell mediated immune reaction to oxypurinol. The highest risk is in the first few months of therapy, especially with higher starting doses of allopurinol. Concurrent diuretics, especially thiazide use, renal insufficiency stage 3, or higher, are major risk factors.
Option C: Complete blood count, liver function tests, renal function, and serum uric acid levels shall be measured every 2 to 5 weeks while titrating the dose until achieving target serum uric acid level and every six months after that. Patients need counseling about the signs and symptoms of AHS with a recommendation to discontinue allopurinol promptly if they develop skin rash concerning AHS, especially early in therapy.
Option D: Allopurinol does not have this function. Allopurinol undergoes metabolism in the liver, where it transforms into its pharmacologically active metabolite, oxypurinol. The half-life of allopurinol is 1 to 2 hours, and oxypurinol is about 15 hours. Both allopurinol and oxypurinol are renally excreted. Allopurinol and oxypurinol both inhibit xanthine oxidase, an enzyme in the purine catabolism pathway that converts hypoxanthine to xanthine to uric acid.