Allopurinol

Its major metabolite alloxanthine is long acting and non competitive inhibitor-primarily responsible for uric acid synthesis inhibition. During allopurinol administration, plasma concentration of uric acid reduced and that of hypoxanthine and xanthine is increased.

Indications

Chronic gout. Secondary hyper-uricaemia, due to cancer chemotherapy, radiation & thiazides or drugs, prevention of uric acid nephro-pathy. Calcium renal lithiasis.

Dosage

Initially 10000 mg daily Maint. : 200-600 mg daily.

Contra-Indications

Children, Acute gout.

Special Precautions

Both allopurinol and uricosurics should not be started during acute attack of gout. Iron therapy not advised with allopurinol. Renal or hepatic impairment. Maintain adequate fluid intake. Paediatrics: Reduced dose necessary. Pregnancy: Should not be used. Lactation: Use with caution. Elderly: Reduced dose may be necessary.

Side Effects

Rashes, Fever, malaise, muscle pain, gastric irritation, headache, nasea, liver damage.

Drug Interactions

Dose of Azothioprine and mercaptopurine should be reduced when administered allupurinol . Probenecid & Salicylates enhance urinary excretion of allopurinol. Enhanced activity of oral hypoglycaemic agents and anticoagulants.