Allopurinol

Question 1

What class is allopurinol?

Answer 1

Xanthine oxidase inhibitor

Question 2

What is the mechanism of action of allopurinol?

Answer 2

Competitive inhibitor of the xanthine oxidase enzyme

Question 3

What is the action of allopurinol?

Answer 3

Prevents the oxidation of xanthine into uric acid, which results in a reduced concentration of uric acid and urate in the tissues

Question 4

What are the indications for allopurinol use?

Answer 4

Prophylaxis of gout
Prophylaxis of uric acid renal stones
Prophylaxis of hyperuraemia associated with chemotherapy

Question 5

What are the important side effects of allopurinol?

Answer 5

Rash - discontinue allopurinol
Hypersensitivity reactions
Hepatotoxicity
Haemolytic anaemia
Leukopenia

Question 6

What are the contraindications to allopurinol?

Answer 6

Ensure patient is adequately hydrated
Renal impairment
Pregnancy
Hepatic impairment

Question 7

What does allopurinol interact with?

Answer 7

ACE inhibitors - increased risk of leukopenia and hypersensitivity
Azathioprine - increased risk of toxicity (adjust dose of azathioprine)
Mercaptopurine - increased risk of toxicity (reduce dose of mercaptopurine)
Thiazide diuretics - increased risk of hypersensitivity

Question 8

How is allopurinol use monitored?

Answer 8

Monitor plasma or urinary uric acid to determine dose adjustments

Question 9

What should the patient be told when taking allopurinol?

Answer 9

They should not stop this medication abruptly
They should take this medication with food and plenty of water