Discontinue use if allergic/hypersensitivity reactions occurs. Severe renal & hepatic impairment. Ischaemic heart disease & CHF; exacerbation &/or onset of CV disease. Cardiac monitoring in patients undergoing chemotherapy for haematologic malignancies at intermediate to high risk of tumor lysis syndrome. Do not start treatment until acute attack of gout has completely subsided. Flare prophylaxis for at least 6 mth w/ an NSAID or colchicine at treatment initiation is recommended. Patients w/ Lesch-Nyhan syndrome & alteration of thyroid function. Concomitant use w/ mercaptopurine/azathioprine. Organ transplant recipients. Perform liver function test prior to treatment, & periodically thereafter. Galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption. Caution before driving, using machinery or participating in dangerous activities. Pregnancy & lactation. Childn <18 yr.