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Pharmacology · TNF inhibitors

Certolizumab pegol !

An anti-TNF antibody fragment (Fab) attached to polyethylene glycol, injected under the skin for Crohn disease and inflammatory arthritis.

Updated 2026-11-01

  • Class: TNF inhibitors
  • Target: Tumour necrosis factor alpha (TNF-α)
  • ATC code: L04AB05

The figure shows TNF-α bound to the certolizumab Fab (without its polyethylene glycol chain).

Target in 3D: Tumour necrosis factor alpha (TNF-α). PDB structure 5WUX (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Certolizumab pegol is a humanised Fab fragment against TNF-α linked to polyethylene glycol (PEG). It neutralises soluble and membrane TNF. Having no Fc portion, it does not fix complement or cause antibody-dependent cell killing; the PEG chain lengthens its time in the body.

  1. Humanised Fab binds TNF-α
  2. PEG chain makes it last longer
  3. No Fc: no complement activation
  4. TNF-driven inflammation falls

Pharmacokinetics

Absorption
Subcutaneous injection
Metabolism
The Fab is broken down like other proteins; PEG is cleared separately

Indications

Adverse effects

Common

  • Upper respiratory infections
  • Injection-site reactions
  • Rash

Contraindications

  • Active serious infection, including active tuberculosis
  • Hypersensitivity to certolizumab pegol

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.

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

Administration and safety

  • Subcutaneous injection; rotate sites.
  • The prefilled syringe may contain latex: ask about latex allergy in the person and the one injecting.

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.

Pregnancy and breastfeeding

The treating team weighs benefits and risks; the baby's doctor is told about exposure in pregnancy before any live vaccine.

Test yourself

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

What makes certolizumab pegol structurally different from other anti-TNF antibodies?

It is only a humanised Fab fragment, with no Fc portion, attached to polyethylene glycol to lengthen its action.

Does certolizumab pegol carry the same tuberculosis warning as other TNF inhibitors?

Yes: latent TB and hepatitis B are screened before starting and infections are watched for throughout.

Which bowel disease is an indication for certolizumab pegol?

Crohn disease.

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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: Certolizumab Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2024); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 39 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.