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Allopurinol/Zyloprim/Lopurin


- Discussion:
- for established gout (Not acute Gout), hyperuricemia of malignancy (or increased cell turnover);
- is useful for established gout with urolithiasis (both for uric acid stones and calcium oxalate stones);
- adult: Initially 100mg PO qd;
- increase by 100mg at weekly intervals until serum uric acid of < 6mg/dl is attained or a total dose of 800 mg/day is attained;
- maintenance dose with mild gout: 300mg PO qd;
- severe gout try 400-600 mg/day in divided doses;
- prophylactic dose of colchicine (0.5mg bid) is recomended by some to prevent an increase in attacks of gout when allopurinal is started;
- secondary hyperuricemia associated with therapy of malignancies:
- 600-800mg/day in divided doses for 3 days;
- must reduce dose in patients with renal insufficiency and in patients receiving mercaptopurine or azathioprine;
- allopurinol should be used carefully with those w/ renal insufficiency, a h/o uric acid stones and those with a 24 hour urinary acid
excretion over 1,100 mg;
- peds: Use only for treating Hyperuricemia of malignancy in children:
- 10mg/kg/24hrs divided q8hr
- (max 600 mg/24 hr period); or 6-10 yrs: 100mg PO tid;

- Allopurinol Interactions and Toxicities:
- interaction w/ coumadin (prolonged PT)
- thiazide diruretics (increased allopurinol toxicity)
- chlorpropamide (increased hypoglycemia)
- cyclophosphamide and other cytotoxic agents (bone marrow suppression);
- hypersensitivity
- rash develops in approximately 2 % of patients treated with allopurinol;
- rash is much more common when taking ampicillin/amoxicillin;
- these rashes are managed with lower dosage or discontinuation of medication;
- allopurinol hypersensitivity syndrome:
- occurs in 1/1000 patients treated with allopurinol and is more common in patients taking allopurinol;
- characterized by fever, exfoliative dermatitis, eosinophilia, leukocytosis, impaired renal function, hepatocellular injury;
- these reactions are severe and may be fatal;
- these are generally managed with prednisone


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Relation between adverse events associated with allopurinol and renal function in patients with gout.