AZATHIOPRINE AND CO-TRIMOXAZOLE

There is some evidence that the risk of haematological toxicity may be increased in renal transplant patients taking azathioprine if they are also given co-trimoxazole or trimethoprim, particularly if both drugs are taken for extended periods. However, other evidence suggests that the drugs may be used together safely, and the combination is commonly used in practice. Azathioprine is rapidly and extensively metabolised to mercaptopurine. Mercaptopurine is therefore expected to interact similarly.
Full blood count should be monitored if azathioprine or mercaptopurine is used. If any abnormalities arise, consider this interaction as a possible cause.