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Disease-Modifying Therapy — MS (Anti-VLA-4 Monoclonal Antibody) Pregnancy: Use only if clearly necessary — limited data; neonatal thrombocytopaenia reported; avoid breastfeeding

Natalizumab

Brand names: Tysabri

Adult dose

Dose: 300 mg
Route: IV infusion over 1 hour
Frequency: Every 4 weeks
Max: 300 mg per infusion
Hospital-supervised infusion only. Pre-medication not routinely required. Monitor during and for 1 hour post-infusion for hypersensitivity. Check JC virus antibody status before initiation and every 6 months — risk of PML stratified by index and prior immunosuppression. RISK MANAGEMENT PROGRAMME (Tysabri TOUCH/TYGRIS) mandatory.

Paediatric dose

Route:
Seek specialist opinion — not licensed under 18 years

Dose adjustments

Renal

No dose adjustment required

Hepatic

No dose adjustment required

Clinical pearls

  • PML risk stratified by: JC antibody positive (especially index >1.5), prior immunosuppressant use, duration of treatment >2 years
  • MRI surveillance every 3–6 months in high-risk patients
  • If PML suspected: stop natalizumab immediately, consider plasmapheresis to accelerate clearance, monitor for IRIS
  • IRIS can be severe on immune reconstitution — treat with IV methylprednisolone
  • Extended interval dosing (every 6 weeks) reduces PML risk while maintaining efficacy in JC-positive patients

Contraindications

  • PML or high PML risk
  • Active systemic malignancy
  • Active opportunistic infections
  • Immunocompromised state not due to MS therapy
  • Hypersensitivity to natalizumab

Side effects

  • PML (progressive multifocal leukoencephalopathy — JC virus reactivation)
  • Infusion reactions (urticaria, rigors, flushing)
  • Headache
  • Fatigue
  • Nasopharyngitis
  • UTI
  • Hepatotoxicity
  • Immune reconstitution inflammatory syndrome (IRIS) if discontinued

Interactions

  • Avoid concurrent immunosuppressants (additive PML risk)
  • Avoid other DMTs concurrently
  • Fingolimod — washout period required before switching

Monitoring

  • JC antibody index every 6 months
  • MRI brain every 6 months (high risk) or annually (low risk)
  • LFTs
  • FBC
  • Infusion reaction monitoring for 1 hour post-dose

Reference: BNFc; BNF 90; NICE TA127 (Natalizumab for RRMS); MHRA Drug Safety Update 2019 PML Risk; AFFIRM Trial. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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