Natalizumab is a humanized monoclonal antibody targeting α4-integrin, indicated for the treatment of relapsing multiple sclerosis (MS).

How to Use Natalizumab

Standard Dosing Regimen

Dose and Frequency: The recommended dose is 300mg, administered as an intravenous infusion once every 4 weeks, with the infusion duration taking approximately 1 hour.

Dosage Form and Specification: It is supplied as a 15mL sterile concentrate (300mg per vial), which must be diluted with 0.9% Sodium Chloride Injection to a final volume of 100mL before use.

Infusion Operation Guidelines

Dilution Requirements: Withdraw 15mL of the medicinal solution and add it to 100mL of 0.9% Sodium Chloride Injection. Gently invert the container to mix; do not shake or freeze.

Stability: After dilution, the solution can be stored at room temperature for a maximum of 8 hours, or refrigerated (2-8°C) for up to 24 hours. It must be brought back to room temperature before use.

Infusion Monitoring: Closely monitor for allergic reactions (e.g., urticaria, hypotension) during the infusion and for 1 hour after the infusion is completed.

Management of Missed Infusions

If a scheduled infusion is missed, administer the missed dose as soon as possible and resume the original once-every-4-week schedule. No dose adjustment is required.

Dose Adjustment of Natalizumab

Dose Adjustment for Immune-Related Adverse Reactions

Allergic Reactions: Permanent discontinuation of treatment is required if systemic allergic reactions (e.g., dyspnea, hypotension) occur.

Infection Risk: Temporarily suspend administration during severe infections (e.g., pneumonia). After the infection is controlled, assess the necessity of restarting treatment.

Liver Enzyme Abnormalities: If persistent Grade 3 elevation of liver enzymes occurs, suspend administration. After liver enzymes return to ≤ Grade 1, consider dose reduction or permanent discontinuation.

Natalizumab Dosage Regimens for Special Populations

Pregnancy and Lactation

Pregnancy: Animal studies have shown an increased risk of fetal thrombocytopenia and anemia (at 7 times the clinical dose). Data in humans are limited. Contraception is required during treatment. Natalizumab should be used during pregnancy only if the potential benefit is clearly justified.

Lactation: It is unknown whether Natalizumab is excreted into human milk. It is recommended to either discontinue the drug or stop breastfeeding.

Pediatric and Geriatric Populations

Pediatric Patients: The efficacy of Natalizumab in patients under 18 years of age has not been established; its use is not recommended.

Geriatric Patients: Clinical study data in elderly patients are insufficient, and individualized assessment is required.

Hepatic and Renal Impairment

No dose adjustment is needed for patients with mild to moderate hepatic or renal impairment. Data in patients with severe impairment are lacking.

Immunosuppressed Patients

Concomitant use with immunosuppressants (e.g., azathioprine) is contraindicated, as it may increase the risk of progressive multifocal leukoencephalopathy (PML).