Tysabri contains Natalizumab, a monoclonal antibody used to treat multiple sclerosis (MS) and Crohn’s disease. It is designed for patients whose conditions are not adequately controlled with other treatments. Tysabri works by reducing immune system attacks on the brain, spinal cord, or intestines, helping to slow disease progression and reduce relapses.

Mechanism of action:
Natalizumab blocks alpha-4 integrin, a protein on the surface of white blood cells. This prevents immune cells from crossing blood vessel walls and entering the brain, spinal cord, or gut, where they can cause inflammation and tissue damage. By inhibiting this migration, Tysabri reduces immune-mediated damage in MS and Crohn’s disease.

Uses:

• Relapsing forms of multiple sclerosis (MS) to reduce relapse rates and slow disability progression

• Crohn’s disease in adults who have not responded well to conventional therapies

• Often used in patients resistant or intolerant to other disease-modifying treatments

Adverse effects:
Common side effects include headache, fatigue, joint pain, urinary tract infections, and infusion-related reactions (fever, chills, rash). Serious but rare side effects include:

• Progressive multifocal leukoencephalopathy (PML), a rare brain infection

• Allergic reactions or hypersensitivity

• Liver problems or infections due to immune suppression