Tumour lysis syndrome (TLS)
TLS is caused by the sudden, rapid death of millions of cells - a particular problem in successful treatment of patients with leukemia or lymphoma. It results from the development of electrolyte and metabolic disturbances that can produce life-threatening complications (esp. hyperuricemia), if not managed appropriately.
No matter what combination of antineoplastic drugs is being used, ALLOPURINOL (a xanthine oxidase inhibitor) is frequently used during chemotherapy of hematologic cancers to prevent hyperuricemia due to tumour cell lysis. The nephrotoxicity and acute gout produced by excessive uric acid are prevented by co-administration of ALLOPURINOL with any chemotherapeutic agent that produces TLS.
Simultaneous administration of ALLOPURINOL and 6-MERCAPTOPURINE results in excessive 6-MP toxicity (because 6-MP is metabolized by xanthine oxidase), unless the dose of 6-MP is reduced to 25-30% of normal.