Azathioprine

Current indication:

For use in patients who are unable to tolerate mycophenolate mofetil.

Dose:

  • Initial –¬†1-2 mg/kg once daily.
  • Maintenance –¬†1 mg/kg once daily.
  • Monitoring¬† – No monitoring of drug levels is required.

Preparation:

Azathioprine is available as 25 mg and 50 mg tablets. There are both generic and brand (Imuran) forms on the market.

Administration:

Virtually exclusively oral although an IV preparation is available.

Contra-indications:

  • Pregnancy.
  • Bone marrow dysfunction, i.e. patients who are known to be leucopaenic or thrombocytopaenic.
  • Reduce dose if hepatic dysfunction is present.

Drug interactions:

Allopurinol and Febuxostat must not be co-prescribed as an inhibition of xanthine oxidase results in potentially fatal accumulation of azathioprine and its metabolites. An alternative uricosuric- benzbromarone is available on a named patient basis. Contact transplant unit pharmacist for further details.

Side Effects:

  • Bone marrow suppression – usually reversible following cessation.
  • Cholestatis and disturbed liver function – again usually reversible.
  • Pancreatitis

Dose may require to be altered depending on WCC, ie. reduce if WCC<4.0, stop if WCC <3.0 and re-introduce at a lower doses when WCC>3.0.

 

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