Off Label Drug Phrase
Allopurinol inhibits the enzyme xanthine oxidase and is commonly used
for prevention of tumor lysis syndrome and gout. However, it is
understood that allopurinol also effects the metabolism of
6-mercaptorpurine (6-MP). Allopurinol directs 6-MP metabolism toward
6-thioguanine (6-TGN), the desired product, and away from 6-
methylmercaptopurine (6-MMPN). 6-MMPN is associated with increased
toxicity in patients. We describe the successful incorporation of
allopurinol therapy in many of our patients with abnormal 6-MP
metabolism.
Data Statement : The data that support the findings of this
study are available from the corresponding author upon reasonable
request.