From the website www.tysabri.com
INDICATIONS AND USAGE
TYSABRI® is indicated as monotherapy for the treatment of patients with relapsing forms of multiple sclerosis to delay the accumulation of physical disability and reduce the frequency of clinical exacerbations. The safety and efficacy of TYSABRI® beyond two years are unknown.
Because TYSABRI® increases the risk of progressive multifocal leukoencephalopathy (PML), an opportunistic viral infection of the brain that usually leads to death or severe disability, TYSABRI® is generally recommended for patients who have had an inadequate response to, or are unable to tolerate, alternate multiple sclerosis therapies.
Safety and efficacy in patients with chronic progressive multiple sclerosis have not been studied.
All users of Tysabri must be enrolled in the TOUCH program:
- Promote informed benefit-risk decisions between prescribers and patients regarding the use of TYSABRI in relapsing MS
- Minimize morbidity and mortality due to PML through early detection with clinical vigilance
- Minimize the risk of PML by treating patients who are not immunocompromised
- Warn against concurrent use with antineoplastics, immunosuppressants or immunomodulators
- Determine the incidence and risk factors for PML and other serious opportunistic infections in patients treated with TYSABRI, as well as the overall safety of TYSABRI in the clinical practice setting
From the website www.umm.edu/ms/tysabri.html
How Does Tysabri® Work?
Tysabri® is a type of medication called a “monoclonal antibody” Tysabri® works by blocking certain types of white blood cells from entering the central nervous system (brain and spinal cord). These white blood cells, known as T- lymphocytes, must adhere, or “stick” to the blood vessel wall in order to enter body tissues such as the central nervous system. Tysabri® blocks the ability of the lymphocytes to stick to the blood vessel wall, thus preventing the lymphocytes from getting into the central nervous system.
In MS it is thought by researchers that certain types of lymphocytes that can cause inflammation are able to enter the central nervous system and cause inflammation. This inflammation can produce damage to the nerve insulation (myelin) and to the nerve itself. This damage disrupts normal nerve transmission and can produce symptoms of MS such as fatigue, numbness, weakness, vision change and walking difficulties. By blocking the ability of these lymphocytes to enter the central nervous system, less inflammatory changes are likely to occur. Therefore there should be less MS attacks (exacerbations) and fewer new lesions.