Treatment of inflammatory bowel disease with azathioprine: how to use it in 1999.

Azathioprine and 6-mercaptopurine are effective drugs in the management of steroid dependent and chronic active inflammatory bowel diseases. They are also well tolerated on the long term. However, their use is still hampered by some drawbacks including delay before efficacy, 20-35% of non responders, relapse at withdrawal of the drugs, possible bone marrow toxicity and other side effects. During the last few years, these drawbacks have been challenged by important studies showing that a better knowledge of the metabolism of these drugs may help to improve their use.