Azathioprine, also marketed under the brand name Azasan (Salix Pharmaceutical), is a thiopurine analog immunosuppressant FDA-approved to prevent organ rejection in renal transplants and reduce signs and symptoms of rheumatoid arthritis. It is also used off-label for several inflammatory conditions, including ulcerative colitis and Crohn’s disease.
As a non-steroid immunomodulator, azathioprine has been widely used to maintain remission and prevent relapses in Crohn’s disease and ulcerative colitis. However, there have also been doubts regarding the long-term effectiveness and safety of the drug when used for inflammatory bowel disease (IBD).
In a retrospective study published this month in the journal JGH Open, Rohan V. Yewale, M.D., from the Institute of Gastroenterology at the SRM Institutes for Medical Science in Chennai, India, evaluated the real-world effects of azathioprine long-term treatment in patients with IBD.
Yewale and his colleagues analyzed data from patients with IBD treated at the Institute of Gastroenterology, Hepatobiliary Sciences and Transplantation in south India and followed between 2013 and 2022. The primary objective was to evaluate the long-term effectiveness and safety of azathioprine treatment.
The researchers evaluated the records of 507 patients and included 320 patients who had been prescribed azathioprine after IBD diagnosis. Of these, 207 had Crohn’s disease, and 113 had ulcerative colitis. The median time to azathioprine initiation was 13 months, and 55% of patients started azathioprine treatment immediately following diagnosis. The median duration of treatment was 33 months, with a total duration of 1,359 patient-years. Close to 30% of patients received azathioprine for over 5 years, 14% for longer than 7 years, and 6% for over 10 years.
About 21% of participants experienced side effects after starting azathioprine. The more common adverse events included myelotoxicity, such as cytopenia, and gastrointestinal side effects, including nausea, vomiting, and abdominal pain. Most azathioprine-related adverse events occurred within the first six months of treatment, and only 1% of patients experienced new side effects after five years of azathioprine exposure. About 40% of participants eventually tolerated azathioprine after a temporary pause in treatment and a dose reduction.
At the last follow-up, 56% of participants were in sustained clinical remission. Excluding patients who received concomitant biologics treatment, about 5% continued to have active disease 16% had more than one relapse after starting azathioprine.
Yewale and his colleagues concluded that long-term azathioprine treatment is safe and effective for maintaining durable clinical remission in patients with IBD. However, they highlight the need for close monitoring for toxicities and adverse events during the first few months of azathioprine therapy.