Natalizumab is a humanized monoclonal antibody used in the treatment of relapsing forms of multiple sclerosis (MS). It works by inhibiting the migration of leukocytes into the central nervous system, thereby reducing inflammatory responses and disease relapses. This article systematically elaborates on the drug from three aspects: administration methods, clinical efficacy, and drug interactions, providing a reference for the rational clinical use of the drug.

How to Use Natalizumab

1. Dosage and Frequency of Administration

The recommended dosage is 300mg per dose, administered via intravenous infusion once every 4 weeks.

Before administration, 15mL of the concentrated solution must be injected into 100mL of 0.9% sodium chloride injection. Gently invert the mixture to combine; shaking should be avoided.

The diluted solution should be used within 8 hours. If refrigerated, it must be brought back to room temperature before infusion.

2. Infusion Process and Monitoring

The infusion time should be controlled at approximately 1 hour. After completion, the infusion line should be flushed with 0.9% sodium chloride.

During the infusion and for 1 hour after its completion, close monitoring of the patient is required to check for hypersensitivity reactions, such as urticaria, hypotension, or difficulty breathing.

In the event of a hypersensitivity reaction, the infusion must be stopped immediately and appropriate medical measures should be taken.

How Effective is Natalizumab

1. Improvement in Clinical Relapse Rate

Phase III studies have shown that in the monotherapy group, the annualized relapse rate decreased from 0.74 to 0.25, representing a relative reduction of 66%.

In the combination therapy group with interferon, the annualized relapse rate dropped from 0.78 to 0.36, a relative reduction of 54%. Additionally, 76% of patients in the monotherapy group remained relapse-free within 13 months, which was significantly higher than the 53% in the placebo group.

2. Changes in MRI Lesions

In the treatment group, the median number of new or enlarging T2 hyperintense lesions decreased to 0, and 60% of patients had no new lesions, compared to only 22% in the placebo group.

Analysis of gadolinium-enhancing lesions revealed that 96% of patients in the treatment group had no active lesions, which was significantly higher than the 68% in the control group.

Drug Interactions of Natalizumab

1. Risks of Combined Use with Immunosuppressants

Combined use of natalizumab with other immunosuppressants (such as azathioprine and methotrexate) may increase the risk of infection.

The concurrent use of these drugs is prohibited in clinical studies, as it may enhance the immunosuppressive effect and lead to an increased incidence of opportunistic infections.

2. Impact of Interferon on Clearance

Combined use with interferon beta-1a can reduce the clearance rate of natalizumab by approximately 30%.

However, safety data from two clinical trials indicate that this pharmacokinetic change does not result in a significant increase in the incidence of adverse reactions. Currently, no adjustment to the dosage of natalizumab is recommended.