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Azathioprine therapy


Azathioprine is indicated for the treatment of active Rheumatoid Arthritis and some other inflammatory arthropathies. It is normally used together with Non Steroidal Anti-inflammatory Drugs particularly in the early stages of treatment. Response to treatment cannot be expected before two or three months and may not occur until after six months of treatment.

CONTRA-INDICATIONS AND WARNINGS

DOSAGE

MONITORING


PRE TREATMENT SCREENING EACH MONITORING VISIT
  • Haemoglobin
  • Total white cell count
  • Neutrophil count
  • Platelet count
  • Urinalysis for protein and blood
  • Biochemical Profile
  • Haemoglobin
  • Total white cell count
  • Neutrophil count
  • Platelet count
  • Liver function tests

ADVERSE EVENTS

LABORATORY EVENTS VALUES ACTION
Leucopaenia < 3.5 x 10 9 /l STOP + seek advice
Neutropaenia < 2.5 x 10 9 /l STOP + seek advice
Thrombocytopaenia < 150 x 10 9 /l STOP + seek advice
Macrocytosis > 100 Check B12 and folate
Sequential falls in WBC or neutrophils > 10% on 3 occasions STOP + seek advice
Sequential falls in Platelets > 10% on 3 occasions STOP unless falls are from high level e.g. 600, 500, 400 x 10 3 which are response to treatment
Elevation of liver enzymes (AST, ALT) > 3x normal STOP + seek advice

CLINICAL ADVERSE EVENTS MANAGEMENT
Hypersensitivity reaction STOP and seek advice
Malaise, dizziness, rigors, muscle pains, disturbed liver function, cardiac dysrhythmias and hypotension. Supportive circulatory measures if severe.
Cough or dyspnoea
  • STOP drug
  • Chest xray and Pulmonary function tests
  • Seek advice
Nausea/anorexia
  • Split dose
  • Reduce dose
  • Take with food, try anti-emetic.
  • STOP if unacceptable
Hair loss
  • Uncommon in this dosage range.
  • Reversible

Azathioprine flow chart
Azathioprine patient advice leaflet

Source: Dr PR Crook, Consultant Rheumatologist.
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