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How does this medication work? What will it do for me?

Natalizumab is a synthetic protein that belongs to the class of medications called selective adhesion molecule inhibitors. It is used to treat people with the relapsing-remitting form of multiple sclerosis (MS) where other MS medications have not worked, or for people who are unable to tolerate other MS therapies.

Natalizumab works by preventing cells of the active immune system from reaching the brain, which can decrease the number of MS attacks, slow the progression of disability, and decrease the number and volume of active brain lesions (damaged brain areas) seen on MRI (magnetic resonance imaging) scans.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are receiving this medication, speak to your doctor. Do not stop receiving this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Each single-use 15 mL vial, free of preservatives, contains 300 mg of natalizumab. Nonmedicinal ingredients: polysorbate 80, sodium chloride, sodium phosphate, dibasic, heptahydrate, sodium phosphate, monobasic, monohydrate, and water for injection.

How should I use this medication?

The usual recommended adult dose of natalizumab is 300 mg given slowly by infusion (over at least 1 hour) into a vein (intravenous infusion) every 4 weeks. The medication will be prepared and given to you by a health care professional, usually in a hospital or a clinic. After you receive your dose of natalizumab, a health care professional will monitor you for 1 hour for reactions to the medication.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are receiving the medication without consulting your doctor.

It is important that this medication be given exactly as recommended by your doctor. If you miss an appointment to receive natalizumab, contact your doctor as soon as possible to reschedule your appointment.

You should then continue to receive your dose of natalizumab every 4 weeks thereafter.

The safety and effectiveness of this drug when used for longer than 2 years has not been established.

Store unopened vials of this medication in the refrigerator. Protect from light, and keep out of the reach of children. Do not shake the container or allow it to freeze.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not use this medication if you:

  • are allergic to natalizumab or any ingredients of this medication
  • have a weakened immune system (e.g., if you have HIV or certain cancers such as leukemia or lymphomas, or are taking certain medications that can weaken the immune system [immunosuppressants])
  • have or have had progressive multifocal leukoencephalopathy (PML), a rare brain infection

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • dizziness
  • headache
  • joint pain or swelling
  • nasal congestion
  • nausea
  • runny nose
  • shivering
  • sore throat
  • tiredness
  • vomiting

Although most of the side effects listed below don’t happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • fever
  • increased heart rate
  • infusion-related reactions (e.g., headache, dizziness, chills, fatigue, or tiredness)
  • itching, skin rash
  • signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
  • signs of bleeding (e.g., bloody nose, blood in urine, coughing blood, bleeding gums, cuts that don’t stop bleeding)
  • signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
  • symptoms of a bladder infection (e.g., frequent urination, pain when urinating, urgent need to urinate, urine with a strong odour, blood in urine, fever or chills, fatigue, confusion)

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • signs of an allergic reaction (e.g., shortness of breath or difficulty breathing; hives; swelling of the eyes, mouth, lips, or throat; or a severe skin rash that peels and blisters)
  • symptoms of progressive multifocal leukoencephalopathy (PML), which are very similar to symptoms of an MS relapse (watch for new MS symptoms or worsening of existing MS symptoms)
  • unusual infections (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Chronic progressive multiple sclerosis (MS): The safety and effectiveness of using this medication by people with chronic progressive MS have not been established. Currently, natalizumab is only recommended for people with the relapsing-remitting form of MS.

Infections: Natalizumab may increase the risk of infections. If you notice any signs of an infection such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness, contact your doctor immediately.

Infusion-related reactions: Some people may experience an infusion-related reaction, including headache, dizziness, fatigue, hives, itching, and chills, up to 2 hours after the start of an infusion. If you notice these symptoms, let your doctor know right away.

Kidney function: If you have kidney disease or decreased kidney function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Natalizumab may cause damage to the liver. If you have liver disease or decreased liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

If you experience symptoms of liver problems (e.g., abdominal pain, persistent vomiting, feeling unwell, fever, itching, yellowing of the skin and eyes, dark urine), contact your doctor immediately.

Progressive multifocal leukoencephalopathy (PML): Natalizumab has been associated with an increased risk of a rare brain infection called progressive multifocal leukoencephalopathy (PML), which can lead to disability or death. The risk of developing this infection increases with the length of time natalizumab is used.

Signs and symptoms of PML include progressive weakness on one side of the body; clumsiness of limbs; vision disturbances; changes in thinking, memory, and orientation; confusion; and personality changes. Some of the symptoms are similar to MS, so if you develop any of these symptoms or any other unusual symptoms, or if your MS gets worse, contact your doctor immediately. Your doctor should do an MRI scan before you start natalizumab to help distinguish a subsequent MS relapse from PML.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. There have been reports of blood abnormalities in newborns born to people who were treated with natalizumab during pregnancy. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are breast-feeding and taking natalizumab, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children and adolescents less than18 years of age.

Seniors: Safe and effective dosing has not been established for seniors. As they are at a higher risk of developing severe adverse reactions to this medication, seniors should be closely monitored by their physician.

What other drugs could interact with this medication?

For a full list of interactions, use the Drug Interaction Checker available on the website.

If you are taking other medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

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Last Updated: 20/05/2024