Primary hyperuricemia of gout, secondary hyper-uricemia due to hematological disorders or antineoplastic therapy, and renal urate stone.

Allopurinol, a structural isomer of hypoxanthine, is a xanthine oxidase inhibitor.

Following oral administration, approximately 80–90% of a dose of allopurinol is absorbed from the GI tract. Allopurinol and oxypurinol are not bound to plasma proteins. Allopurinol and oxypurinol are distributed into milk. Allopurinol and allopurinol sodium are rapidly metabolized by xanthine oxidase to oxypurinol, which is pharmacologically active. About 5–7% of an oral allopurinol dose is excreted in urine unchanged within 6 hours after ingestion. About 70% of the administered daily dose is excreted in urine as oxypurinol and an additional 20% appears in feces as unchanged drug within 48–72 hours. The half-lives of allopurinol and oxypurinol are about 1–3 hours and 18–30 hours, respectively, in patients with normal renal function and are increased in patients with renal impairment.

Hypersensitivity to allopurinol, idiopathic hemochromatosis, nursing mothers and children.

C

Safe; from limited data, the milk/plasma ratios is between 0.9-1.4.

Rash, exfoliative, urticarial or purpuric lesions, nausea, vomiting, agranulocytosis, anemia, peripheral neuritis, diarrhea, headache.

Adults: Initial dose: 100mg/day PC, then increased by 100mg at weekly interval until serum uric level < 6mg/dl. Maximum dose: 300mg/dose, 800mg/day.

In renal impairment, reduce initial dosage as follows:
ClCr 60ml/min 200 mg/day,ClCr 40ml/min 150 mg/day,ClCr 20ml/min 100 mg/day,ClCr 10ml/min 100 mg Q2 days, ClCr＜10ml/min 100 mg Q3 days.