Azathioprine in a dose of 1.5 mg per kg per day is a well accepted alternative therapy in CD of either small or large bowel. It is often suggested in patients who have progressive disease, or who relapse quickly when steroids are tapered. Steroids are often continued for 3 months as there is a delay in onset of Azathioprine effect. Once there appears to be a clinical response, steroids can be tapered. If remission occurs, long term treatment is warranted.
Most patients tolerate it very well with no side effects.
Monthly CBC monitoring should be done for bone marrow suppression, but this is rarely a problem with the 1.5 mg per kg dosage. Concerns about long term risk of lymphoma are being played down in recent literature, though I mention it to all recipients. If remission occurs, and steroids can be withdrawn, patients may go for years with a clinical remission. A 1995 study in the NEJM shows promising results with methotrexate 25 mg per week IM for 16 weeks. If a response is obtained I reduce the dose to 15 mg per week and give it orally.