How does allopurinol work? Name 3 indications for its use.
Allopurinol inhibits the enzyme xanthine oxidase, which is responsible for the conversion of the purine metabolites hypoxanthine and xanthine into uric acid. With the use of allopurinol, uric acid concentration falls and the concentrations of these precursors rise. This also provides a negative feedback signal that decreases purine production.
- Recurrent gouty attacks (more than 3 in the span of 1 year)
- Gouty tophi
- Renal insufficiency with hyperuricemia
Other indications include recurrent nephrolithiasis with hyperuricemia, and prophylaxis for tumour lysis syndrome.
*Note that allopurinol is generally a life-long therapy and that both its initiation and discontinuation can exacerbate gout or cause a flare. It should not be started or stopped during an acute flare of gout.