Azathioprine

Question 1

Monitoring

Answer 1

Full blood count, renal function, liver function

Question 2

Warning Signs

Answer 2

• Malaise, dizziness, diarrhoea, fever, myalgia, rash (hypersensitivity reactions)
• Hypotension
• Nausea and vomiting
• Unexplained bruising or bleeding, infection

Question 3

Actions Required

Answer 3

• Patients taking concurrent allopurinol should reduce the azathioprine dose to one-quarter
• Consider measuring thiopurine methyltransferase (TPMT) activity in patients before initiation
of therapy. Risk of myelosuppression is increased in patients with reduced activity of TPMT.
Patients with absent TPMT activity should not receive thiopurine drugs; those with reduced
activity should be treated under specialist supervision
• Counsel patients to report immediately any signs or symptoms of bone marrow suppression
including unexplained bruising, bleeding or infection
• In patients treated for rheumatoid arthritis, it may be appropriate to withdraw the drug if
nausea, vomiting or diarrhoea occurs
• Dose should be reduced in the elderly

Question 4

Interactions

Answer 4

• Increased risk of anaemia and/or leucopenia with ACE inhibitors
• Anticoagulant effect of coumarins reduced
• Increased risk of haematological toxicity with allopurinol
• Increased risk of generalised infection, which could be life threatening with live vaccines