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Pharmacology · TNF inhibitors

Infliximab !

A chimeric (part mouse) antibody against TNF-α given as an intravenous infusion, mainly for Crohn disease, ulcerative colitis and arthritis.

Updated 2026-11-01

  • Class: TNF inhibitors
  • Target: Tumour necrosis factor alpha (TNF-α)
  • ATC code: L04AB02

The figure shows human TNF-α bound to the Fab fragment of infliximab.

Target in 3D: Tumour necrosis factor alpha (TNF-α). PDB structure 4G3Y (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Infliximab is a chimeric IgG1κ monoclonal antibody: human constant regions with mouse variable regions. It neutralises soluble and membrane TNF-α and prevents it from activating its receptors, which calms inflammation in the gut wall, the synovium and the skin. Its mouse portion makes antibodies against the drug more likely; these reduce its effect and raise infusion reactions, and methotrexate or azathioprine given with it lowers that risk.

  1. Chimeric antibody binds TNF-α
  2. TNF can no longer activate its receptors
  3. Gut, joint and skin inflammation settles
  4. Anti-drug antibodies can blunt the effect

Pharmacokinetics

Absorption
Intravenous infusion only
Distribution
Stays mainly in the bloodstream
Half-life
About one to one and a half weeks

Indications

Adverse effects

Common

  • Infusion reactions (fever, chills, itching, flushing)
  • Upper respiratory infections and sinusitis
  • Headache
  • Nausea and abdominal pain

Contraindications

  • Moderate or severe heart failure at higher doses
  • Previous severe hypersensitivity to infliximab or to mouse proteins
  • Active serious infection, including active tuberculosis

Key interactions

Anakinra or abatacept
More serious infections without added benefit; not combined.
Live vaccines
Risk of infection by the vaccine strain; avoided during treatment.
Other immunosuppressants (glucocorticoids, methotrexate, azathioprine)
Additive risk of infection; azathioprine or mercaptopurine with a TNF blocker has been linked to hepatosplenic T-cell lymphoma.
Tocilizumab
Added immunosuppression and infection risk.

What is monitored

  • Latent tuberculosis test before starting, and watch for active TB during and after treatment even if the test was negative
  • Hepatitis B screening before starting
  • Signs of infection at every visit
  • Skin checks for cancer
  • Vital signs before, during and after each infusion
  • Liver tests

Administration and safety

  • Intravenous infusion only, given slowly over hours, through a set with an in-line low-protein-binding filter.
  • The powder is reconstituted and diluted just before use and the infusion is started soon after.
  • Not infused in the same line with other drugs.
  • Emergency drugs for anaphylaxis are at hand; premedication may be ordered.
  • Several biosimilars exist; the product is checked against the prescription.

Nursing care

  • Confirm that the latent TB test and hepatitis B screening are done (and treated if positive) before the first dose.
  • Do not give the dose during an active infection; report fever, cough, night sweats or weight loss.
  • Check that vaccines are up to date before starting; live vaccines are avoided during treatment.
  • Ask about heart failure and neurological disease before starting.
  • Watch for infusion reactions during and after the infusion; slow or stop it and call the team if they appear.

Pregnancy and breastfeeding

It crosses the placenta and is found in the baby for months after birth; live vaccines for the exposed infant are delayed for at least six months.

Test yourself

Think of the answer, then tap the question to see it.

Why is methotrexate given together with infliximab in rheumatoid arthritis?

It improves the response and reduces antibodies against the chimeric antibody, which would otherwise lower its effect and raise infusion reactions.

What equipment is required to give infliximab?

An intravenous set with an in-line, sterile, low-protein-binding filter; the infusion runs slowly over hours.

In which heart condition is infliximab contraindicated at higher doses?

Moderate or severe heart failure.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: Infliximab Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2021); DailyMed - INFLIXIMAB injection, powder, lyophilized, for solution (DailyMed (U.S. National Library of Medicine), 2025); Altered Immunocompetence | Vaccines & Immunizations | CDC (Centers for Disease Control and Prevention (CDC), 2024); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.