Infliximab for the Treatment of Inflammatory Bowel Disease: An Overview of Drug History and Delivery

Written by: Patrick Hamilton, MD, FRCPC & Dr. Cathy Lu MD, MSc, FRCPC

Updated: February 18th, 2025

What is Infliximab and where did it come from?

Infliximab is a medication used to treat inflammatory bowel disease (IBD), including both Crohn’s disease and ulcerative colitis. The initial formulation of infliximab known as Remicade^â has been used for over twenty years, gaining approval in Canada for the treatment of Crohn’s disease in 2001 and Ulcerative Colitis in 2006¹. With its longstanding use, infliximab is well studied and known to be effective at achieving and maintaining control of IBD, allowing patients to feel better and stay better for a long time while decreasing their need for surgery^2-4. In addition to treating inflammation in the bowel, infliximab is effective at treating fistulas, which are abnormal connections between the intestines and the skin or other organs⁵.

Infliximab is also known to be effective at treating extra-intestinal manifestations of IBD including skin changes, and inflammation in the eyes and joints⁶. Over the years, many studies have looked at the long-term safety of infliximab. These studies found that while it is generally safe, it can cause some side effects including infections and allergic reactions. These side effects are rare, and risk can be reduced with proper preventative measures⁷.

How does Infliximab work?

In people with IBD, the immune system mistakenly attacks the digestive tract, causing inflammation. Infliximab works by targeting a specific protein in the body called tumor necrosis factor-alpha (TNF-α). TNF-α is a substance in the body that causes inflammation, which is a part of the immune system’s response to injury or infection. Infliximab helps by blocking TNF-α, which reduces inflammation and helps the digestive tract heal. It does this by binding to TNF-α and preventing it from attaching to its receptors on cells. This stops the chain reaction that leads to inflammation. Infliximab also helps reduce the activity of certain white blood cells in the immune system which are involved in the inflammatory process. By reducing the activity of these cells, infliximab helps decrease the overall immune response and inflammation in the digestive tract⁸.

What are Biosimilars?

When a biologic is first produced and approved for use, it is referred to as an “originator”, as it is the original version of a biologic used to treat a disease. It takes a significant amount of time and money to develop a new biologic, and therefore to help pay for this cost and promote research, new biologics are protected by patent in Canada for a period of twenty years. This means that during this time, no other companies can produce biosimilar medications.

Biosimilars are medications that are made by different companies after the original patent expires. They are designed to be very similar to the originator biologic and have the same effect, but are made using different processes, and therefore are not exactly the same. As previously mentioned, Remicade^â was the originator infliximab biologic, and following expiration of its patent, various infliximab biosimilars were approved in Canada including Inflectra in 2016 as well as Renflexis in 2017 Despite small differences, studies have shown that infliximab biosimilars are just as safe and effective as Remicade^â. They have similar effects on the body and help control inflammation in the same way. Using infliximab biosimilars can also help lower the cost of treatment, making it more affordable^9-10.

How is Infliximab given?

Infliximab, including its biosimilars and the originator Remicade^â is typically given intravenously, which means it is directly delivered into the blood stream. This process is often done at a clinic, hospital, or infusion center. The medication is typically given at weeks zero, two, and six, and then every eight weeks onward¹¹. Ongoing infusions may be given more frequently if a patient’s Gastroenterologist decides this is needed.

What is Subcutaneous Infliximab?

In 2024, Health Canada approved RemsimaTMSC, the first subcutaneous formulation of an infliximab biosimilar available for use in Canada for the treatment of IBD¹². As a subcutaneous formulation, Remsima^TM SC is administered using a self-injector device usually given into the thigh, abdomen, or upper arm. To start a patient on subcutaneous infliximab, they begin with an intravenous induction phase. This involves receiving 5mg/kg intravenous infliximab at weeks zero, two, and six to quickly reduce inflammation.

After this induction phase, the patient can be treated with the subcutaneous form for treatment maintenance with injections starting at week eight, with ongoing injections every two weeks. Patients who are already being treated with intravenous infliximab maintenance therapy can be switched over at any time to Remsima SC¹³. Real world evidence studies and registrational controlled trials in IBD patients have shown that subcutaneous infliximab is well tolerated and effective at getting patients with IBD to feel better and stay better for a long time^14-21.

Who should consider Subcutaneous Infliximab?

Subcutaneous infliximab is an option for patients and caregivers hoping to administer their medication at home, without the need to travel to a clinic, hospital, or infusion center. Alternatively, some patients who are not comfortable with self-injection of medications may prefer intravenous formulations that are more hands-off, and administered by a nursing team. Either way, the patient can be assured they are receiving the same infliximab ‘molecule’/medication, which has been used in medical practice for over ten years.

While studies have shown that subcutaneous infliximab is effective, there are some people for whom it may not be the right choice. Studies have shown that individuals receiving larger and more frequent doses of intravenous Infliximab (i.e. 10 mg/kg every four weeks) are at an increased risk of relapse when switching from intravenous to subcutaneous formulations at the approved dosing of 120mg every two weeks (120mg q2w)^15-16. Clinical data suggested that most of these patients who relapsed at the approved dose of 120mg every 2 weeks could be recaptured by increasing the dose to either 240mg every 2 weeks or 120 mg weekly^15-16. The recommendation is that these patients on infliximab IV maintenance at 10 mg/kg every four weeks should immediately start at 240mg every 2 weeks or 120 mg weekly when switched to subcutaneous infliximab.

Overall: Infliximab is an extensively studied, well tolerated, and effective medication for the treatment of inflammatory bowel disease.

Download the ‘Infliximab for IBD’ Infographic!

About the Authors:

Dr. Cathy Lu is an IBD gastroenterologist and assistant professor of medicine at the University of Calgary. She completed her internal medicine and gastroenterology residency at the University of Alberta. She has also completed a joint advanced IBD fellowship with specialization in intestinal ultrasound. Her primary research interests are in strictures in Crohn’s disease, intestinal ultrasound, and biomarkers in diagnosis, monitoring, and treatment response in IBD.
Patrick Hamilton is a first-year Gastroenterology fellow at the University of Calgary. He completed medical school at the University of Alberta, and Internal Medicine residency at the University of Calgary. He has plans to undergo further subspeciality training within the field of inflammatory bowel disease.

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