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.