Infliximab: Anti-TNF-α Monoclonal Antibody for Inflammatory Diseases
Infliximab (Remicade) is a chimeric (mouse/human) IgG1 monoclonal antibody that binds both soluble and membrane-bound TNF-α with high affinity, neutralising its pro-inflammatory effects.
Approved for Crohn's disease, ulcerative colitis, rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, plaque psoriasis, and paediatric Crohn's disease. Administered IV every 8 weeks after induction.
Mechanism of Action
Neutralises both soluble and membrane-bound TNF-α, blocking signalling through TNFR1 and TNFR2 receptors. Reduces inflammation, inhibits tissue destruction, and may induce apoptosis of TNF-expressing cells (antibody-dependent cell cytotoxicity, ADCC).
Indications & Use
Moderate-to-severe Crohn's disease (luminal and fistulising), UC, RA (with methotrexate), ankylosing spondylitis, psoriatic arthritis, chronic plaque psoriasis, paediatric CD (≥6 years), paediatric UC (≥6 years).
Dosage
Standard: 5 mg/kg IV at weeks 0, 2, 6 (induction), then every 8 weeks (maintenance). CD fistulising: 5 mg/kg same schedule. RA: 3 mg/kg with methotrexate. Dose may be increased to 10 mg/kg or interval shortened if response inadequate.
Side Effects
Infusion reactions (5–10%): flushing, headache, chest tightness — manage by slowing infusion. Serious: increased risk of infections (especially TB — screen before starting), reactivation of latent infections (hepatitis B). Rare: lymphoma, paradoxical psoriasis, drug-induced lupus, demyelination.
Drug Interactions
Methotrexate: reduces immunogenicity (anti-drug antibody formation) — preferred combination. Other biologics/JAK inhibitors: avoid combination (increased immunosuppression). Anakinra: contraindicated. Live vaccines: avoid.
Contraindications
Active TB or other severe infections, moderate-severe heart failure (NYHA III/IV), hypersensitivity to murine proteins. Avoid in pregnancy (especially 3rd trimester — neonatal immunosuppression).
Frequently Asked Questions
Why must TB be excluded before starting infliximab?
TNF-α is critical for granuloma formation, which contains Mycobacterium tuberculosis. Inhibiting TNF-α can cause reactivation of latent TB, sometimes severe and disseminated. All patients must have a tuberculin skin test or IGRA, chest X-ray, and latent TB treated before starting.
What are infusion reactions and how are they managed?
Infusion reactions occur during or within 2 hours of infusion — flushing, urticaria, dyspnoea, hypotension. Slow the infusion rate; premedicate with antihistamine/paracetamol for subsequent infusions. Anaphylaxis is rare but requires immediate treatment.
Can infliximab biosimilars be used instead?
Yes. Multiple biosimilars (e.g., Inflectra, Remsima) are approved and widely used. They have equivalent efficacy and safety to originator Remicade. Non-medical switching is generally accepted for most patients.
References
- EMA Remicade SPC 2023
- ECCO Guidelines: IBD 2022
- Smolen JS et al. ARD 2020 (RA recommendations)
Medical Disclaimer: This information is for educational purposes only and does not replace professional medical advice.