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TYSABRI | natalizumab
Drug Class: Integrin Receptor Antagonist
Manufacturer: Biogen Idec Inc
Approval Date: November 2004
What is Tysabri and its mechanism of action?
Tysabri is an injectable agent FDA approved for treatment of Multiple Sclerosis (MS) and Crohn’s Disease. Tysabri is an integrin receptor antagonist which binds to the alpha 4-subunit on integrins of leukocytes (white blood cells) and inhibits the adhesion of leukocytes to their receptors. Leukocytes are part of the immune system. By binding to integrins Tysabri prevents leukocytes from crossing blood vessel walls and entering sites of inflammation. In Multiple Sclerosis, Tysabri prevents leukocytes from entering brain cells resulting in fewer MS lesions.
What does Tysabri Treat?
How effective is Tysabri?
Multiple Sclerosis: The efficacy of Tysabri compared to placebo in the treatment of MS was evaluated after receiving 28 weeks of treatment. At the end of 2 years 67% of MS patients who received Tysabri 300 mg every 4 weeks reported no relapse or disabilities compared to 41% of patients on the placebo treatment. Only 17% of patients on Tysabri treatment experienced an increase in their symptoms compared to 29% of patients in the placebo group.
Crohn’s Disease: The efficacy of Tysabri compared to placebo in the treatment of Crohn's was studied in a 12-week long trial and results were reported at two different time points, after 8 and 12 weeks. At the end of week 8, 32% of patients on monthly treatment of Tysabri 300 mg experienced a decrease in symptoms compared to 21% of patients on placebo treatment. At the end of week 12, 37% of patients on monthly treatment of Tysabri 300 mg experienced a decrease in symptoms compared to 25% of patients on placebo.
Interesting facts about Tysabri
What is the dosage of Tysabri?
Tysabri 300 mg is supplied in a 15 mL sterile vial and it is infused thorough IV infusion over approximately one hour every 4 weeks. Tysabri must be administered within 8 hours of dilution. Patients must be observed during and 1 hour after the administration of Tysabri to insure there is no emergency reaction to the drug. If patients with Crohn’s Disease do not see a clinical response after 12 weeks of initiating the treatment or if they are required to be in long-term steroid treatment, Tysabri is discontinued.
What are warnings and precautions for Tysabri
Who should not use Tysabri:
Pregnancy: Pregnancy Category C. There are no adequate studies in pregnant women. Women who become pregnant while receiving Tysabri should consider enrolling in the Tysabri Pregnancy Exposure Registry by calling 1-800-456-2255.
Nursing Mothers: Tysabri has been detected in human milk but the effects on infants are unknown.
What are the possible side effects of Tysabri?
Common: Headache, fatigue, joint pain, urinary tract infection, lower respiratory tract infection, severe diarrhea, vaginal discomfort, depression, abdominal discomfort, and rash.
Serious: Progressive multifocal leukoencephalopathy (PML), herpes encephalitis and meningitis, liver failure, immunosuppression and increased risk of infections.
What are Tysabri drug interactions?
In treatment of Crohn’s Disease, Tysabri should not be given in combination with immunosuppressants (cyclosporine, methotrexate) or TNF-alpha inhibitors.
What is the price of Tysabri?
The annual cost for Tysabri, which includes 13 infusions is $28,400.
How to obtain prescription cost assistance for Tysabri
To download a free drug discount card or receive financial assistance visit:
Tysabri Prescribing Information. Biogen Idec Inc. December 2013
More Articles by Samar Borhani, PharmD Intern