gout

Question 1

allopurinol indications

Answer 1

• prevent gout
• prevent uric acid and calcium oxalate renal stones
• prevent hyperuricaemia and tumour lysis syndrome associated with chemo

Question 2

allopurinol MOA

Answer 2

Xanthine oxidase inhibitor. this enzyme metabolises xanthine to uric acid. inhibition = lower palsma uric acid and reduces precipitation

Question 3

SE allopurinol

Answer 3

• worsens gout if started durign acute attack. can be reduced by coprescription of NSAID or colchine in initiation
• skin rash; mild or SJS or TENs
• allopurinol hypersensitivity syndrome = rare, life threatening reaction = fever, eosinophilia, LNA and involvement of other organs

Question 4

CI to allopurinol

Answer 4

• acute attacks of gout for initiation
• recurrent skin rashes
• severe hyeprsensitivity

Question 5

dose adjustments of allopurinol in which aptients

Answer 5

• renal and hepatic impairment as metabolised by liver, and excreted by kidneys

Question 6

interactions with allopurinol

Answer 6

• active metabolite of axathioprine = mercatopurine is metabolisedn by xanthine oxidase. so increased risk of toxicity
• coprescription with ACE-I or thiazides = increases risk of hypersensitivity reactions annd with amoxicillin = skin rash

Question 7

how to initiate allopurinol

Answer 7

• start low e.g. 100mg daily and titrate up to 200-600mg OD/BD.
• in gout prescribe naproxen or colchine and continue for 1 month after serum uric acid levles return to normal to avoid triggering acute attack
• if used in cancer - start before chemo

Question 8

when should patients take allopurinol

Answer 8

• after meals and encourage patient to drink lots

Question 9

when to check serum uric acid concentrations in gout

Answer 9

• 4 weeks after initiating allopurinol or after change in dose
  aim <300 micromol/l

Question 10

what drugs can induce gout

Answer 10

• thiazides
• loops
• low dose aspirin (inhibits renal excretion of uric acid)