Tysabri is a prescription medication approved by the Food and Drug Administration (FDA) for treating adults with relapsing forms of multiple sclerosis (MS). Tysabri is also known by its drug name, Natalizumab. Tysabri is not a cure for MS, but it can decrease the number of flare-ups, help delay disability, and help prevent the development of new brain lesions. Tysabri is a monotherapy, which means it cannot be combined with any other MS drug. Due to the risk of serious side effects, it is usually only recommended for patients who have not responded well to other MS drugs.
Tysabri is not recommended for people who have weakened immune systems or who have ever had a certain virus called the John Cunningham virus. Tysabri is not appropriate for pregnant women, women who might become pregnant, or women who are breastfeeding.
Tysabri is an immunomodulator, or in other words, a drug that modulates the immune system. It is a genetically engineered antibody, or type of protein used by the immune system to identify and neutralize substances. Tysabri is believed to work by attaching to immune cells called lymphocytes (a type of white blood cell) and preventing them from crossing the blood-brain barrier. By blocking the lymphocytes’ access to the central nervous system, Tysabri prevents them from attacking the brain and nerves and causing the lesions that result in MS symptoms.
How do I take it?
Tysabri is taken as an intravenous infusion once every 28 days. It takes one hour to receive the infusion, and you will be monitored for infusion reactions for one more hour before leaving.
In order to take Tysabri, you must be accepted to a restricted program called the TOUCH Prescribing Program. TOUCH, which stands for Tysabri Outreach: Unified Commitment to Health, is sponsored by the drug’s manufacturer. You will have to answer many questions about your health history that relate to your immune system, and you may undergo a blood test for John Cunningham virus. You may also receive a magnetic resonance imaging (MRI) scan to check for any sign of brain infection. If you are accepted, you will go to a medical facility to receive Tysabri each month.
Always follow your doctor’s instructions exactly when taking Tysabri.
In clinical studies, 67 percent of those who took Tysabri had no flare-ups during the two-year treatment period, compared with 41 percent of those who took a placebo. Only 17 percent of those who took Tysabri experienced progression of physical disabilities, compared with 29 percent of those who took a placebo. Ninety-seven percent of participants had not developed new brain lesions at the end of two years, compared with 72 percent of those who took a placebo.
Rare but serious side effects of Tysabri include liver damage and increased risk for contracting a brain infection called progressive multifocal leukoencephalopathy (PML). People taking Tysabri may also have an elevated risk of developing leukemia and other cancers.
Signs of liver damage can include dark brown urine, yellow skin, and extreme tiredness. Call your doctor if you experience any of these.
More common side effects are fatigue, stomach pain, nausea, vomiting, sore throat, headache, skin irritation at the injection site, and general skin problems such as bleeding, crusting, or blistering. Since Tysabri lowers your body’s immune system defenses, it can make it easier to contract urinary tract, respiratory system, and other infections.
Seek medical help immediately if you experience symptoms of an allergic reaction such as trouble breathing, severe dizziness, a rash, or itching or swelling of the face, tongue, and throat.