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Tysabri® (natalizumab)

Tysabri (natalizumab) is an intravenous medication that is used alone or in combination with other drugs to treat multiple sclerosis (MS). Manufactured by Biogen-Idec, Tysabri is not a cure for MS, but helps to decrease the number of attacks of symptoms such as muscle spasms or weakness. When the drug is administered, the cells that cause inflammation and damage nerve fibers and their insulation (myelin) are prevented from migrating from the bloodstream into the brain.

Why is Tysabri prescribed?

Tysabri is a monoclonal antibody prescribed to treat patients with relapsing forms of MS in order to reduce the frequency of flare-ups.

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What are the FDA approved uses for Tysabri?

Tysabri was approved by the FDA in 2004 as the first humanized monoclonal antibody for the treatment of MS

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What are the side effects of Tysabri?

Common side effects associated with Tysabri include fatigue, headache, joint pain, redness/irritation at the IV site, and changes in menstrual cycles.

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Tysabri warnings and alerts

Tysabri’s maker, Biogen-Idec, took Tysabri off the market in February 2005 after three people out of about 3,000 patients taking Tysabri in clinical trials developed a rare, serious brain infection called progressive multifocal leukoencephalopathy (PML). Two of those patients died. However, as of June 2006, the FDA is rolling out a risk-minimization plan along with Tysabri’s return to the market. The plan is designed to inform patients, doctors, pharmacists, and infusion centers about Tysabri’s risks and to quickly flag PML cases in patients taking Tysabri. Under the new plan, patients must enroll in a risk-minimization program designed by Biogen-Idec before taking Tysabri. Potential patients also need to get a brain scan using magnetic resonance imaging (MRI). Doctors who prescribe Tysabri, pharmacies that dispense the drug, and infusion sites that administer the drug must also enroll in the risk-minimization program.

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Tysabri drug contradictions

Tysabri shouldn’t be used in combination with other immune-system modifying drugs and/or in patients who have or have had progressive multifocal leukoencephalopathy (PML).

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Tysabri FAQs

If the FDA is allowing Tysabri back on the market, are their guidelines involved?

The FDA has recommended a risk-minimization program with mandatory patient registration and periodic follow-up for patients being reintroduced to Tysabri. The newly approved plan is designed to identify any PML cases as quickly as possible and to learn more about which patients may be at higher risk. The plan’s rules include:

  • Tysabri will only be prescribed, distributed, and infused by prescribers, infusion centers, and pharmacies registered with the program.
  • Tysabri will only be administered to patients who are enrolled in the program.
  • Before starting Tysabri, patients must get magnetic resonance imaging (MRI) to help differentiate future MS symptoms from PML.
  • Patients on Tysabri are to be evaluated at 3 and 6 months after the first infusion and every 6 months after that, and their status will be reported regularly to Biogen Idec.

Why was Tysabri approved by the FDA in the first place?

A study called the AFFIRM Monotherapy Trial showed a 66% reduction in the rate of MS relapses when Tysabri was used as a stand-alone treatment. The Sentinel Add-on Study showed a 54% reduction in the rate of relapses when Tysabri was used in conjunction with Avonex (interferon beta-1a). Additionally, MRIs showed that Tysabri prevented brain lesions from developing or enlarging.

What is Progressive Multifocal Leukoencephalopathy (PML)?

PML is an opportunistic viral infection of the brain that usually leads to death or severe disability and occurs in people with inadequate immune response and a poor prognosis, such as AIDS and cancer patients. The incidence of PML, once quite rare, is rising as the numbers of people living with persistently compromised immune systems rises. An estimated 2-7% of people with HIV disease will develop PML. The infection also occurs among people undergoing long-term chemotherapy for cancer. PML is not considered a contagious disease.

What are the symptoms of PML?

About 45% of people with PML experience vision problems, most often a blindness affecting half of the visual field of each eye. Mental impairment affects about 38% of people with PML. Eventually, about 75% experience extreme weakness. Other symptoms include lack of coordination, paralysis on one side of the body (hemiparesis), and problems in speaking or using language.

Can I file a lawsuit if I have suffered damages from taking Tysabri?

Possibly. While all medications have certain, anticipated side effects, a drug manufacturer has a duty to inform physicians adequately regarding the known risks associated with its drugs. If a manufacturer fails to do so, it can be held responsible to patients who are injured as the result of inadequate warnings, under a legal theory known as “product liability.” Depending upon the particular circumstances of your case, damages may include recovery for any of the following:

  • Past and future medical expenses
  • Past and future pain and suffering
  • Lost wages
  • Loss of future earning capacity
  • Emotional distress

If you or a loved one has experienced any health problems while taking Tysabri, you should contact your doctor immediately. You may also wish to contact an experienced Tysabri lawyer to discuss your legal options. As all legal claims are subject to time limits, however, you may risk forfeiture of your right to financial compensation if you delay.

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