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Allopurinol 300mg Tablets

Read time: 17 mins
Last updated: 07 Sep 2020
Published: 07 Sep 2020

4.1 Therapeutic indications

Allopurinol is indicated in:

1. Conditions of excess body urate including gout. Allopurinol is used to reduce urate levels in the body when these levels are excessive (serum is theoretically saturated with urate at a concentration between 0.38-0.42 mmol (6.4-7.0 mg%)). The higher levels seen in practice may be accounted for by (a) the formation of supersaturated solutions: (b) protein binding of urate. Excess body urate may be indicated by hyperuricaemia and /or hyperuricosuria. It may lead to deposition of urate in the tissues or it may be present with no obvious signs or symptoms. The main clinical manifestations of urate deposition are gouty arthritis, skin tophi and/or renal involvement. Excess body urate is frequently of idiopathic origin but may also be found in association with other conditions including the following: neoplastic disease and its treatment; certain enzyme disorders (in particular Lesch Nyhan syndrome); renal failure; renal calculus formation; diuretic therapy and psoriasis.

2. Calcium renal lithiasis: Allopurinol is of benefit in the prophylaxis and treatment of calcium renal lithiasis in patients with raised serum or urinary uric acid.

Allopurinol and its major metabolite, oxipurinol, act by inhibiting the enzyme xanthine oxidase which catalyses the end stage of the metabolism of purines to uric acid. Allopurinol and its metabolites are excreted by the kidney but the renal handling is such that allopurinol has a plasma half-life of about one hour whereas that of oxipurinol exceeds 18 hours. Thus therapeutic effect may be achieved by once-a-day dosage.

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