What is Infliximab and How Does It Work?
Infliximab is a chimeric monoclonal antibody made from human and mouse proteins. It acts as a tumor necrosis factor (TNF) inhibitor by targeting and neutralizing TNF-alpha, a protein involved in inflammation. In autoimmune diseases, the overproduction of TNF-alpha causes chronic inflammation and tissue damage. By blocking TNF-alpha, infliximab helps reduce inflammation, relieve symptoms, and slow disease progression in moderate to severe autoimmune conditions.
FDA-Approved Uses for Infliximab
Infliximab is approved for treating several autoimmune and inflammatory disorders, particularly when other treatments have failed. Its approved uses include:
Inflammatory Bowel Diseases
- Crohn's Disease (CD): For adults and children (6 years and older) with moderately to severely active CD who haven't responded to other treatments, including both luminal and fistulizing disease.
- Ulcerative Colitis (UC): For adults and children (6 years and older) with moderately to severely active UC who haven't adequately responded to other medications.
Rheumatic Diseases
- Rheumatoid Arthritis (RA): Used in adults with moderately to severely active RA, usually with methotrexate, to reduce symptoms, improve function, and prevent joint damage.
- Ankylosing Spondylitis (AS): For adults with active AS, it helps reduce signs and symptoms, including spinal pain and stiffness.
- Psoriatic Arthritis (PsA): Approved for adults with active PsA to reduce arthritis signs and symptoms and prevent structural damage.
Dermatological Conditions
- Chronic Severe Plaque Psoriasis (PsO): For adults with chronic, severe plaque psoriasis that is extensive, disabling, or hasn't responded to other treatments.
How Is Infliximab Administered?
Infliximab is given intravenously (IV) in a healthcare setting, unlike medications taken orally or by self-injection. The process typically involves:
- Induction Phase: Initial infusions to control the disease, often at weeks 0, 2, and 6.
- Maintenance Phase: Less frequent infusions, typically every 6 or 8 weeks, to maintain remission.
- Infusion Process: Infusions take about 2 hours in a clinic or hospital, with monitoring by a healthcare provider for reactions.
Potential Side Effects and Precautions
Infliximab can cause side effects, ranging from mild to serious.
Common Side Effects: Headache, fever, chills, nausea, rashes, itching, and fatigue.
Serious Risks and Precautions: Increased risk of serious infections (like TB), a potential increased risk of certain cancers (especially lymphomas in young males with IBD), new or worsening heart failure, severe liver injury, and infusion reactions. Patients are screened for TB before starting treatment.
Comparison: Infliximab vs. Adalimumab
Both infliximab and adalimumab are anti-TNF-alpha biologics, but they differ in administration, origin, and specific uses.
| Feature | Infliximab | Adalimumab |
|---|---|---|
| Mechanism | Chimeric monoclonal antibody. | Fully human monoclonal antibody. |
| Administration | Intravenous (IV) infusion in a clinic. | Subcutaneous (SC) self-injection. |
| Frequency | Typically every 6-8 weeks after induction. | Typically every 1-2 weeks. |
| Immunogenicity | Can develop antibodies. | Less prone to immunogenicity. |
| Cost | Often cost-effective, with biosimilars available. | Brand name expensive, biosimilars exist. |
| Best for... | Conditions requiring IV, or less frequent dosing. | Self-injection at home, more frequent dosing. |
Conclusion
Infliximab is a significant treatment for serious autoimmune diseases, particularly when traditional therapies are insufficient. By blocking TNF-alpha, it effectively reduces inflammation and damage in conditions like Crohn's, RA, and psoriasis. While it requires IV administration and carries risks, its efficacy is well-established. Patients should discuss infliximab's benefits and risks with their doctor to see if it's right for them. More information is available from resources like the Mayo Clinic website.
