Crohn's disease is an inflammatory bowel disorder marked by chronic inflammation of the GI tract. Various treatment strategies for Crohn's disease are employed, such as immunomodulatory agents, glucocorticoids, and biologics or anti-TNF therapy. Azathioprine (Imuran), a commonly used immunomodulatory drug for Crohn's disease, is converted in the body to mercaptopurine, which inhibits purine biosynthesis and cell proliferation. Both are utilized in severe cases of Inflammatory Bowel Disease (IBD) or for patients resistant to steroids. These drugs help maintain remission, prevent recurrence post-surgery, and treat fistulas in Crohn's disease. Adverse effects include pancreatitis, fever, rash, arthralgias, nausea, vomiting, bone marrow suppression, and liver function test elevations.

Methotrexate (Trexall), another immunomodulatory agent, inhibits dihydrofolate reductase, blocking DNA synthesis and inducing cell death. It also inhibits purine metabolism, T-cell activation, cytokine production, and other vital processes, providing anti-inflammatory effects. It is reserved for steroid-resistant or steroid-dependent IBD patients and is used to maintain remission while reducing the formation of anti-drug antibodies. It is administered parenterally with a dose of 15-25 mg/week for induction and maintenance of remission in Crohn's disease. Various adverse effects are nausea, loose stool, stomatitis, cutaneous eruption, CNS symptoms, alopecia, fever, and hematologic abnormalities.