Infliximab for the treatment of Crohn's disease: review and indications for clinical use in Canada.

Crohn's disease is a chronic inflammatory disorder of the gastrointestinal tract. It may affect any portion of the gastrointestinal tract from the mouth to the anus. Symptoms typically include cramping abdominal pain, diarrhea (which may be bloody) and nausea. As the severity of the illness worsens, patients may experience constant abdominal pain, vomiting, weight loss and fever. From the perspective of the patient, disease symptoms significantly impair quality of life, and interfere with their work environment and activities of daily living. Unfortunately, there is no cure for Crohn's disease. Patients experience a chronic, relapsing course characterized by recurrent flares of their disease. Conventional medical treatment of Crohn's disease includes the use of non-specific anti-inflammatory drugs (5-aminosalicylic acid agents, prednisone, budesonide), immunosuppressives (6-mercaptopurine, azathioprine, methotrexate) and antibiotics. A variable onset of action, incomplete response rates and a significant risk of adverse effects characterize current therapies. Although surgery is frequently used to treat complications or medically refractory disease, postoperative recurrence is a common problem. Infliximab, a murine chimeric monoclonal antibody directed toward tumour necrosis factor-alpha, is a highly effective treatment of active Crohn's disease. In randomized, placebo-controlled clinical trials, 33% of patients treated with infliximab 5 mg/kg achieved remission (Crohn's Disease Activity Index score less than 150), compared with only 4% of those receiving placebo (P<0.001). Additionally, infliximab is the only drug therapy shown to be effective for the treatment of fistulizing Crohn's disease. In studies done to date, infliximab appears to be well tolerated and has a favourable side effect profile.