Natalizumab is a recombinant humanized monoclonal antibody targeting α4-integrin. It exerts its therapeutic effect by inhibiting the migration of immune cells, but may trigger severe immune-related adverse reactions.

Precautions for Natalizumab Administration

High-Risk Populations

Pregnancy: Animal studies have shown that it may affect fetal development (e.g., thrombocytopenia), and the necessity of treatment needs to be evaluated.

Lactation: Whether the drug is excreted in breast milk is not yet clear; it is recommended to discontinue the drug or terminate breastfeeding.

Pediatric and Geriatric Patients: The safety in patients under 18 years of age has not been established, and data on populations over 65 years of age are limited.

Prevention and Control of Infusion-Related Risks

Allergic Reactions: Approximately 1.3% of patients experience severe systemic reactions, mostly occurring within 2 hours of infusion. Symptoms include urticaria, hypotension, dyspnea, etc. Immediate discontinuation of the drug and emergency treatment are required.

Operational Specifications: The infusion duration must be ≥1 hour, and the patient should be observed for 1 hour after the infusion ends. Intravenous bolus injection or rapid infusion is prohibited.

Immunosuppression and Infection Risks

Concomitant Medications: Concomitant use with other immunosuppressants (e.g., azathioprine) is prohibited, as it may increase the risk of opportunistic infections.

Infection Management: In clinical studies, the infection rate was approximately 1 case per patient-year, mainly involving respiratory tract and urinary tract infections. Administration must be suspended if an active infection occurs.

Drug Preparation and Storage

Dilution Requirements: 300mg of the drug must be diluted with 100mL of 0.9% Sodium Chloride Injection; the use of other solvents is prohibited.

Stability: After dilution, the solution can be stored at room temperature for ≤8 hours or refrigerated for ≤24 hours. Freezing or shaking should be avoided.

Natalizumab Administration Monitoring

Laboratory Indicators

Complete Blood Count: Monitor the increase in lymphocytes and monocytes (drug effect); changes in neutrophils may indicate infection.

Liver Function: Detect ALT/AST at baseline and every 3 months; if the abnormal value is ≥3 times the upper limit of normal (ULN), drug administration must be suspended.

Thyroid Function: Regularly monitor TSH and free T4 (the incidence of thyroiditis is approximately 6%).

Immunogenicity Monitoring

Antibody Detection: Screen for anti-drug antibodies every 12 weeks; approximately 10% of patients develop antibodies (6% are persistent).

Impact: In patients with positive antibodies, the serum drug concentration drops sharply (<1mcg/mL vs. 17mcg/mL), and the therapeutic effect is significantly reduced.

Management: Permanent discontinuation of the drug is required for patients with persistent positive antibodies to avoid the risk of subsequent infusion reactions.

Imaging and Clinical Symptom Tracking

MRI Evaluation: Monitor T1 gadolinium-enhancing lesions and T2 hyperintense lesions annually to assess disease activity.

Neurological Function: Conduct regular Expanded Disability Status Scale (EDSS) scoring, combined with the frequency of relapses.