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

Peginterferon beta-1a belongs to the class of medications called immunomodulators. More specifically, it belongs to the family of medications known as interferons. Interferons are naturally occurring substances that our bodies produce to fight infections and tumours. Man-made or synthetic versions of interferon have been made to target specific types of cells.

Immunomodulators modify the way our body's defense system works. Peginterferon beta-1a is used to treat the relapsing-remitting form of multiple sclerosis (MS). It helps to decrease the frequency of flare-ups of the illness and slows the progression of the illness.

Peginterferon beta-1a is thought to work by altering the immune system to reduce its harmful effects on the myelin sheath (see below). It does not cure MS, but it may decrease the frequency of relapses and reduce the number of damaged brain areas as seen on MRI scans.

MS is a disease that affects the way the nerves in our body work. It is an autoimmune disease (the immune system attacks the body) and cannot be spread from person to person. In MS, damage occurs to the myelin sheath, a protective layer that wraps around a nerve like insulation around electrical wiring. Normally, this sheath allows electrical messages to be sent down the nerve quickly and efficiently. If this insulation is injured, electrical signals in the central nervous system will not be sent properly. For unknown reasons, in MS, the immune system sees the myelin as foreign and attacks it.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

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 taking this medication, speak to your doctor. Do not stop taking 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 take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Pre-filled syringe

63 μg
Each pre-filled syringe containing 0.5 mL of sterile, clear liquid for subcutaneous injection contains 63 μg of peginterferon beta-1a.

94 μg
Each pre-filled syringe containing 0.5 mL of sterile, clear liquid for subcutaneous injection contains 94 μg of peginterferon beta-1a.

125 μg
Each pre-filled syringe containing 0.5 mL of sterile, clear liquid for subcutaneous injection contains 125 μg of peginterferon beta-1a.

Pre-filled pen

Each single pre-filled syringe containing 0.5 mL of 63 μg, 94 μg, or 125 μg peginterferon beta-1a is contained within a single-use, disposable, injection device (pre-filled pen). 

How should I use this medication?

The starting dose of peginterferon beta-1a is 63 μg injected subcutaneously(under the skin), followed by 94 μg injected subcutaneously 2 weeks later, and then 125 μg injected subcutaneously 2 weeks after the second dose. The regular dose of peginterferon beta-1a is 125 μg injected subcutaneously every 2 weeks thereafter. Peginterferon beta-1a is available as an injection only. It comes in single-use pre-filled syringes or injection pens.

There are special directions enclosed in the package with the injection. Read these directions carefully before using the medication. Follow the instructions closely to avoid accidentally contaminating the medication or needle and giving yourself an infection, or from damaging the equipment or losing the medication.

Peginterferon beta-1a is used with the guidance and supervision of a doctor. Your doctor or nurse will assist you in the preparation and injection of your first dose (or first few doses). Do not attempt to inject this medication on your own until you completely understand how to inject a dose.

Rotate the injection sites (arms, thighs, upper buttocks, or stomach) to minimize injection site skin irritation.

Many things can affect the dose of 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 taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, and it is more than 7 days until your next dose, inject it as soon as possible and continue with your regular schedule. If it is less than 7 days until your next dose, inject the missed dose and wait 2 weeks before administering any future doses. Do not inject 2 doses of this medication within 7 days of each other. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Before using a syringe, check it carefully to ensure that there are no particles in it. Do not use the syringe if the pen or syringe is broken or the solution is not clear and colourless. Store this medication in the refrigerator and protect it from freezing. Store the medication in its original packaging to protect it from light and keep it out of the reach of children.

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 take this medication if you:

  • are allergic to peginterferon or any ingredients of the medication
  • are allergic to interferon beta

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.

  • feeling weak
  • flu-like symptoms (e.g., headache, muscle aches, chills or fever)
  • increased body temperature
  • itchy skin
  • joint or muscle pain
  • nausea
  • tiredness
  • reactions at the injection site (e.g., redness, pain, swelling, bruising)
  • 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:

  • bruising more easily than usual
  • 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)

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

  • signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)

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.

Blood counts: This medication can decrease the number of neutrophils (a type of white blood cell that helps fight infection), red blood cells (which carry oxygen), and platelets (which help your blood to clot). Your doctor will do blood tests to monitor this. If you notice any signs of infection (e.g., fever, chills, or sore throat) or unusual bleeding or bruising, or unusual and unexplained tiredness, contact your doctor immediately.

Depression and suicidal behaviour: If you have or have had depression or bipolar disorder, you may be at an increased risk of feeling agitated (restless, anxious, aggressive, emotional, and feeling not like yourself), or wanting to hurt yourself or others. If you develop severe depression or experience other mood or behaviour changes, stop using this medication and contact your doctor immediately. If you have thoughts or feelings about harming yourself, get immediate medical attention.

Fever and flu-like symptoms: This medication can cause fever and other flu-like symptoms such as chills and headache. Gradually increasing the dose of this medication when you start using it should also help reduce these symptoms. Your doctor may suggest that you take acetaminophen if you develop these symptoms.

If you have a persistent fever while using this medication, contact your doctor.

Heart problems: This medication may worsen symptoms of heart disease. If you have heart disease such as angina, congestive heart failure, or arrhythmia, 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. Contact your doctor as soon as possible if you develop symptoms of heart problems such as shortness of breath, chest pain, rapid heartbeat, or swollen ankles.

Liver function: Peginterferon beta-1a may cause decreased liver function and occasionally, liver failure. If you have liver problems, 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. Your doctor may recommend regular liver tests while you are using this medication. If you have severe changes in liver function, your doctor may recommend that you take a lower dose of this medication or stop taking it altogether.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Seizures: There have been occasional reports of seizures occurring with interferons. Seizures are more likely to occur when higher doses of this medication are taken. If you have a history of epilepsy or medical conditions that increase the risk of seizures, 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.

Thyroid problems: Some people taking this medication develop changes in the function of their thyroid. Symptoms of these changes include increased sweating, rapid heartbeat, weight loss without a change in your diet or amount of exercise you get, or feeling emotional or anxious. Contact your doctor if you experience these symptoms.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately. It is important to use effective birth control while taking this medication.

Breast-feeding: It is not known if peginterferon beta-1a passes into breast milk. If you are a breast-feeding mother and are taking this medication, 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. 

What other drugs could interact with 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.

Blood counts: This medication can decrease the number of neutrophils (a type of white blood cell that helps fight infection), red blood cells (which carry oxygen), and platelets (which help your blood to clot). Your doctor will do blood tests to monitor this. If you notice any signs of infection (e.g., fever, chills, or sore throat) or unusual bleeding or bruising, or unusual and unexplained tiredness, contact your doctor immediately.

Depression and suicidal behaviour: If you have or have had depression or bipolar disorder, you may be at an increased risk of feeling agitated (restless, anxious, aggressive, emotional, and feeling not like yourself), or wanting to hurt yourself or others. If you develop severe depression or experience other mood or behaviour changes, stop using this medication and contact your doctor immediately. If you have thoughts or feelings about harming yourself, get immediate medical attention.

Fever and flu-like symptoms: This medication can cause fever and other flu-like symptoms such as chills and headache. Gradually increasing the dose of this medication when you start using it should also help reduce these symptoms. Your doctor may suggest that you take acetaminophen if you develop these symptoms.

If you have a persistent fever while using this medication, contact your doctor.

Heart problems: This medication may worsen symptoms of heart disease. If you have heart disease such as angina, congestive heart failure, or arrhythmia, 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. Contact your doctor as soon as possible if you develop symptoms of heart problems such as shortness of breath, chest pain, rapid heartbeat, or swollen ankles.

Liver function: Peginterferon beta-1a may cause decreased liver function and occasionally, liver failure. If you have liver problems, 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. Your doctor may recommend regular liver tests while you are using this medication. If you have severe changes in liver function, your doctor may recommend that you take a lower dose of this medication or stop taking it altogether.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Seizures: There have been occasional reports of seizures occurring with interferons. Seizures are more likely to occur when higher doses of this medication are taken. If you have a history of epilepsy or medical conditions that increase the risk of seizures, 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.

Thyroid problems: Some people taking this medication develop changes in the function of their thyroid. Symptoms of these changes include increased sweating, rapid heartbeat, weight loss without a change in your diet or amount of exercise you get, or feeling emotional or anxious. Contact your doctor if you experience these symptoms.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately. It is important to use effective birth control while taking this medication.

Breast-feeding: It is not known if peginterferon beta-1a passes into breast milk. If you are a breast-feeding mother and are taking this medication, 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. 

What medications can interact with this medication?

There may be an interaction between peginterferon beta-1a and any of the following:

  • theophyllines (e.g., aminophylline, oxtriphylline, theophylline)
  • zidovudine

If you are taking any of these 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.

Medications other than those listed above may interact with this medication. 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.