Natalizumab is a recombinant humanized IgG4κ monoclonal antibody. By specifically inhibiting α4-integrin-mediated immune cell migration, it is used for the treatment of relapsing multiple sclerosis.

Precautions for Natalizumab Administration

High-Risk Populations

Pregnant Women: Animal studies have shown that placental transfer of Natalizumab may cause fetal thrombocytopenia. The use of this drug requires a careful weighing of its benefits and risks.

Lactating Women: It has not been clearly determined whether Natalizumab is excreted in human milk. It is recommended to either suspend breastfeeding or discontinue the drug.

Patients with Concomitant Immunosuppression: Concurrent use with other immunosuppressants (e.g., azathioprine) is prohibited, as this may increase the risk of infection.

Infusion Management Standards

Preparation Requirements: Natalizumab can only be diluted with 0.9% sodium chloride injection to a volume of 100mL. Mixing with other drugs or using a side-port injection is prohibited.

Infusion Duration: Strictly control the infusion rate; intravenous infusion must last for 1 hour. After the infusion is completed, flush the tubing with normal saline.

Observation Period: Closely monitor vital signs during the infusion and within 1 hour after the infusion ends. Ensure that emergency equipment is fully prepared.

Prevention and Control of Hypersensitivity Reactions

Incidence: The incidence is <1%, but hypersensitivity reactions may present as immediate-type allergies (e.g., urticaria, hypotension, dyspnea).

Management: If a hypersensitivity reaction occurs, discontinue the drug immediately and permanently contraindicate its use thereafter.

Recommendation: Extend the observation time to 2 hours after the first infusion.

Monitoring During Natalizumab Administration

Infection Screening

Baseline Screening: Screen for latent infections such as hepatitis B and tuberculosis at baseline.

During Treatment: Monitor for signs of respiratory tract or urinary tract infections during treatment.

Hematological Monitoring

Cell Count Changes: Lymphocyte and monocyte counts may increase (recovery occurs within 16 weeks after drug discontinuation).

Thrombocytopenia Risk: There is a risk of thrombocytopenia (especially in fetuses exposed to the drug during pregnancy, who require postnatal monitoring).

Immunogenicity Testing

Antibody Screening: Test for anti-drug antibodies every 12 weeks; approximately 6% of patients develop persistent antibodies.

Impact on Efficacy and Safety: Patients with positive anti-drug antibodies show a significant reduction in treatment efficacy and are more prone to infusion reactions.