The successful treatment of autoimmune hepatitis with 6-mercaptopurine after failure with azathioprine.

Although the treatment of choice for autoimmune hepatitis is glucocorticoids, their side effects make long-term use undesirable. Therefore, other immunosuppressive agents have been used to replace glucocorticoids in the long-term treatment of autoimmune hepatitis, including azathioprine, a purine analogue. It is derived from 6-mercaptopurine, and these two drugs are often used interchangeably. However, these drugs have different toxicity profiles and may have clinically relevant differences in immunosuppressive activity in individual patients. We report 3 patients with autoimmune hepatitis who either could not tolerate or failed to improve on azathioprine but responded well to 6-mercaptopurine.