Form, strength, how it’s given, and more

If you have multiple sclerosis (MS) or Crohn’s disease, your doctor may prescribe Tysabri for you.

Tysabri is a prescription drug used to treat certain types of multiple sclerosis or Crohn’s disease in adults.

The active ingredient in Tysabri is natalizumab. (An active ingredient is what makes a medicine work.) Tysabri is a biologic medicine, which means it is made from living cells. It belongs to a group of medicines called integrin receptor antagonists. You will receive Tysabri by intravenous (IV) infusion at a health clinic. (An IV infusion is an injection into your vein given over a period of time.)

This article describes the dosage of Tysabri infusions, as well as its strength and how you will receive the medicine. To learn more about Tysabri, check out this in-depth article.

To note: This article covers typical Tysabri dosages provided by the drug manufacturer. But your doctor will prescribe the dose of Tysabri that is right for you.

You will receive doses of Tysabri at an infusion center certified to administer this medicine. For more information, see “How is Tysabri given?” section below. Your doctor will explain the typical Tysabri dosing schedule and other information about infusion doses to you.

What is the form of Tysabri?

Tysabri comes as a liquid solution in a single-dose vial. You will receive the medicine as an intravenous (IV) infusion (an injection into a vein given over a period of time.)

How strong is Tysabri?

Tysabri comes as 300 milligrams (mg) per 15 milliliters (mL) of solution.

What are the usual doses of Tysabri?

The information below outlines commonly recommended doses.

Dosage for multiple sclerosis (MS) and Crohn’s disease

The common dose for MS is 300 mg of Tysabri given as an IV infusion over 1 hour every 4 weeks. But your doctor may suggest an extended dose, which would change your dosing frequency so that you receive Tysabri once every 6 to 8 weeks.

It is important to note that the extended dosage of Tysabri is not FDA approved. This is considered an off label dosage. (With an off-label dosage, a doctor prescribes a dosage other than the FDA-approved dosage.)

Prolonged dosing can be done to reduce your risk of developing progressive multifocal leukoencephalopathy (PML).* But more studies are needed to determine if prolonged dosing could reduce the risk of PML while still being effective in managing your condition. To learn more about extended dosing, talk to your doctor. And see the “Ask a Pharmacist” section below.

* Tysabri has a framed warning for the risk of PML. For more information, see the “Boxed warning” section at the beginning of this article.

Is Tysabri used long term?

Yes, Tysabri is generally used as a long-term treatment. If you and your doctor determine that Tysabri is safe and effective for you, you will likely receive it for the long term. Your doctor will review your treatment at times to determine if you should continue to receive Tysabri.

You will receive Tysabri as an intravenous (IV) infusion (an injection into a vein given over a period of time). The infusion usually lasts 1 hour. You will also be monitored for 1 hour after your infusion for at least the first 12 infusions to make sure you do not have a reaction to Tysabri.

Tysabri is only given in certain certified clinics under a special Risk Assessment and Mitigation Strategy (REMS) prescription program called TOUCH. This is due to the serious risks of progressive multifocal leukoencephalopathy (PML)* with the drug.

Your doctor can give you more information about the treatment centers where you can receive Tysabri. You can also find out more on the manufacturer’s website.

* Tysabri has a framed warning for the risk of PML. For more information, see the “Boxed warning” section at the beginning of this article.

It is important to keep all of your appointments to receive doses of Tysabri. But if you miss an appointment, call the clinic as soon as you remember. They will arrange your appointment so that you can receive the missed dose. They can also adjust your future appointments as needed to keep you on track with your treatment plan.

If you need help remembering when to take your Tysabri dose, try using a medication reminder. This may include setting an alarm or downloading a reminder app to your phone.

The sections above describe typical dosages provided by the drug manufacturer. If your doctor recommends Tysabri, he will prescribe the dosage that is right for you.

If you have any questions or concerns about your current dosage, talk to your doctor.

Here are some sample questions you may want to ask your doctor:

  • Does receiving medicine by intravenous (IV) infusion increase my risk of side effects?
  • Would a different dosage of Tysabri reduce my risk of side effects?
  • Should my dosage change if Tysabri is not working for my condition?

For more tips on managing your condition and treatment updates, subscribe to Healthline’s multiple sclerosis (MS) or inflammatory bowel disease (IBD) newsletters.

And if you’re looking for a support group of people with the same chronic illness as you, consider joining a Bezzy Community. You will find an MS community and an IBD community that you can join through the Bezzy homepage.

Disclaimer: Healthline has made every effort to ensure that all information is factually correct, complete and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or for all specific uses.

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