Musculoskeletal System

Question 1

What are the common indications for the use of allopurinol?

Answer 1

1. To prevent recurrent attacks of gout
2. To prevent uric acid and calcium oxalate renal stones
3. to prevent hyperuricaemia and tumour lysis syndrome associated with chemotherapy

Question 2

What is the mechanism of action of allopurinol?

Answer 2

Xanthine oxidase inhibitor

Question 3

How does allopurinol work

Answer 3

inhibition of xanthine oxidase therefore loss of metabolism of xanthine to uric acid. therefore lowers plasma uric acid concentrations and reduces precipitation of uric acid in the joints or kidneys.

Question 4

What are the important adverse effects of allopurinol?

Answer 4

1. Can trigger or worsen an acute attack of gout.
2. Most common side effect is a skin rash, which may be mild or may indicate a more serious hypersensitivity reaction such as stevens-Johnson syndrome or toxic epidermal necrolysis. 3. Allopurinol hypersensitivity syndrome is a rare, life-threatening reaction to allopurinol that can include fever, eosinophilia, lymphadenopathy and involvement of other organs, such as the liver and skin.

Question 5

What warning should be considered with allopurinol?

Answer 5

1. Allopurinol should not be started during acute attacks of gout, but can be continued if a patient is already established on it, to avoid sudden fluctuations in serum uric acid levels.
2. Recurrent skin rash signs of more severe hypersensitivity to allopurinol are contraindications to therapy.
3. Allopurinol is metabolised in the liver and excreted by the kidney. The dose should therefore be reduced in patients with severe ∆renal impairment or ∆hepatic impairment.