DRUG INTERACTIONS. In patients receiving mercaptopurine or IMU-RAN (azathioprine), the concomitant administration of 300 to 600 mg of ZYLOPRIM (allopurinol) per day will require a reduction in dose to approximately one third to one fourth of the usual dose of mercaptopurine or azathioprine. Allopurinol, sold under the brand name Zyloprim among others, is a medication used to decrease high blood uric acid levels. It is specifically used to prevent gout, prevent specific types of kidney stones and for the high uric acid levels that can occur with chemotherapy. The most up to date, comprehensive, regulated information about medicines. Easy to use, trusted and recommended by healthcare professionals Allopurinol 300 mg to 600 mg (increased in 100 mg increments each month until serum uric acid was 6.0 mg/dL), tablets, orally, once daily for up to approximately 83 months to participants with mildly impaired renal function or normal renal function (estimated creatinine clearance [eCLcr] ≥60 mL/min) or allopurinol 200 mg to 400 mg (increased. Detailed Allopurinol dosage information for adults and children. Includes dosages for Gout, Hyperuricemia Secondary to Chemotherapy and Calcium Oxalate Calculi with Hyperuricosuria; plus renal, liver and dialysis adjustments. 2.2 Patients With Renal Impairment Patients with decreased renal function require lower doses of allopurinol than those with normal renal function. Allopurinol has the following structural formula below: Allopurinol is known chemically as 1,5-dihydro-4 H-pyrazolo [3,4-d]pyrimidin-4-one. It is a xanthine oxidase inhibitor which is administered orally. Allopurinol and colchicine are two medications that can be used to treat gout. This lesson will discuss the similarities and differences between. Adjust dosage according to patient tolerance and response. Recommended initial dose is 100 mg PO once daily, increased by 100 mg PO weekly until serum urate concentrations decrease to 6 mg/dL or less, or until reaching a maximum daily dose of 800 mg/day. The dose of allopurinol for treating gout is 200-600 mg daily depending on severity. The dose for treating high uric acid blood levels due to chemotherapy is 100-800 mg daily starting 1 or 2 days before chemotherapy.