[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Multiple sclerosis disease-modifying therapies](https://durgical.com/en/pharmacology/classes/multiple-sclerosis-disease-modifying-therapies/) › Natalizumab

# Natalizumab

## Multiple sclerosis disease-modifying therapies?

Multiple sclerosis disease-modifying therapies

A monthly infused antibody against alpha-4 integrin that keeps lymphocytes out of the brain; its key risk is PML from the JC virus.

Updated Nov 1, 2026

Also called: Natalizumab-sztn

## Quick facts

**Group**
[Multiple sclerosis disease-modifying therapies](https://durgical.com/en/pharmacology/classes/multiple-sclerosis-disease-modifying-therapies/)

**Target**
Alpha-4 integrin (α4β1 and α4β7)

**Used for**
Relapsing forms of multiple sclerosis

**Key effects**
Headache and tiredness · Joint and limb pain · Urinary

**Monitor**
Anti-JC virus antibodies before

**ATC**
L04AG03

No doses: the clinician sets them by the current guideline.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Safety Contraindications
- Key interactions
- What is monitored
- Administration and safety
- Nursing care

- Study Test yourself

- Connections Connections

## Mechanism of action

◎**Alpha-4 integrin (α4β1 and α4β7)**Natalizumab

ⓘ The figure shows the Fab fragment of natalizumab bound to the alpha-4 subunit of the α4β7 integrin headpiece; the drug is the antibody itself, so there is no small ligand.

**Target in 3D:** Alpha-4 integrin (α4β1 and α4β7). PDB structure 4IRZ (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/4IRZ) · Drag to rotate · pinch to zoom

Natalizumab is a humanized monoclonal antibody against the alpha-4 subunit shared by α4β1 and α4β7 integrins on leukocytes. The interaction of α4β1 with VCAM-1 on endothelial cells is needed for T cells to cross the blood-brain barrier; blocking it strongly reduces inflammatory cell entry into the CNS. Blocking α4β7 with MAdCAM-1 reduces homing to the inflamed gut, the basis of its use in Crohn disease.

- Natalizumab binds alpha-4 integrin on leukocytes
- α4β1 can no longer bind VCAM-1 on brain vessels
- T cells fail to cross the blood-brain barrier
- Fewer relapses, but less immune surveillance of the brain

## Indications

- Relapsing forms of multiple sclerosis (including active secondary progressive) [Multiple sclerosis →](https://durgical.com/en/conditions/multiple-sclerosis/)
- Moderate to severe Crohn disease not controlled by other treatments [Crohn disease →](https://durgical.com/en/conditions/crohn-disease/)

## Adverse effects

### Common

- Headache and tiredness
- Joint and limb pain
- Urinary, respiratory and vaginal infections
- Rash and diarrhoea

### Serious (rare, important)

- Progressive multifocal leukoencephalopathy (PML) from the JC virus (boxed warning): can cause death or severe disability
- Immune reconstitution inflammatory syndrome (IRIS) after stopping for PML
- Herpes encephalitis and meningitis
- Serious allergic reactions, mostly within 2 hours of the start of an infusion
- Liver injury
- Low platelets (bruising, bleeding)

## Contraindications

- Allergy to natalizumab
- Current or previous PML, or conditions that weaken immunity (HIV, leukaemia, lymphoma, organ transplant), usually rule it out

## Key interactions

**Immunosuppressants (e.g., mitoxantrone, azathioprine, methotrexate, cyclophosphamide, mycophenolate), now or in the past**
Higher risk of PML and other infections

**Plasma exchange**
An anti-JCV antibody test is not reliable within 2 weeks of plasma exchange

## What is monitored

- Anti-JC virus antibodies before and periodically during treatment
- Questions about new neurological symptoms before every infusion, and for 6 months after the last dose
- MRI if PML is suspected
- Liver tests and blood counts as needed

## Administration and safety

- Given only in registered infusion centres within a restricted distribution programme
- Intravenous infusion over about one hour, every 4 weeks
- Observation for 1 hour after the infusion, at least for the first 12 infusions

## Nursing care

- Before each infusion: ask about fever, infection, shingles and new neurological symptoms
- During and after the infusion: watch for hives, itching, wheeze, trouble breathing, dizziness, chest pain, flushing
- Teach PML warning signs: one-sided weakness that worsens, clumsiness, changes in thinking, memory, vision or personality
- Teach signs of liver injury and low platelets

## Pharmacokinetics

**Absorption**
Intravenous infusion over about an hour

**Elimination**
Long-acting antibody, given every 4 weeks

## Memory aid

«Natalizumab shuts the alpha-4 door»: T cells cannot enter the brain, but neither can the immune surveillance that keeps JC virus in check.

## Test yourself

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

## What does natalizumab bind?

The alpha-4 subunit of α4β1 and α4β7 integrins on leukocytes.

## Which three factors raise the risk of PML on natalizumab?

Anti-JCV antibodies, longer treatment (more than 2 years) and previous immunosuppressants.

## Besides MS, which disease is natalizumab used for?

Crohn disease.

## How long are patients observed after an infusion in the first months?

One hour after the infusion, for at least the first 12 infusions.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/pharmacology/natalizumab/)

[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## Connections

## Related drugs 4

- [Ocrelizumab](https://durgical.com/en/pharmacology/ocrelizumab/)
- [Fingolimod](https://durgical.com/en/pharmacology/fingolimod/)
- [Methotrexate](https://durgical.com/en/pharmacology/methotrexate/)
- [Methylprednisolone](https://durgical.com/en/pharmacology/methylprednisolone/)

## Related conditions 2

- [Multiple sclerosis](https://durgical.com/en/conditions/multiple-sclerosis/)
- [Crohn disease](https://durgical.com/en/conditions/crohn-disease/)

[← Back to the class: Multiple sclerosis disease-modifying therapies](https://durgical.com/en/pharmacology/classes/multiple-sclerosis-disease-modifying-therapies/)

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

Sources: [Natalizumab Injection: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a605006.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [RCSB PDB - 4IRZ: Crystal structure of A4b7 headpiece complexed with Fab Natalizumab](https://www.rcsb.org/structure/4IRZ) (RCSB Protein Data Bank, 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L04AG) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/natalizumab/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/natalizumab/