Allopurinol is used in the prevention of gout. It works by inhibiting xanthine oxidase.

Initiating allopurinol prophylaxis

• it has traditionally been taught that urate-lowering therapy (ULT) should not be started until 2 weeks after an acute attack, as starting too early may precipitate a further attack. The evidence base to support this however looks weak

• in 2017 the BSR updated their guidelines. They still support a delay in starting urate-lowering therapy because it is better for a patient to make long-term drug decisions whilst not in pain

  • the key passage is:

    'Commencement of ULT is best delayed until inflammation has settled as ULT is better discussed when the patient is not in pain'

• initial dose of 100 mg od, with the dose titrated every few weeks to aim for a serum uric acid of < 300 µmol/l. Lower initial doses should be given if the patient has a reduced eGFR

• colchicine cover should be considered when starting allopurinol. NSAIDs can be used if colchicine cannot be tolerated. The BSR guidelines suggest this may need to be continued for 6 months

Indications for allopurinol

• the British Society of Rheumatology Guidelines now advocate offering urate-lowering therapy to all patients after their first attack of gout

• ULT is  recommended if:

  particularly

  • = 2 attacks in 12 months

  • tophi
  • renal disease
  • uric acid renal stones
  • prophylaxis if on cytotoxics or diuretics

• patients with Lesch-Nyhan syndrome often take allopurinol for life