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

[February 1, 2012]

Peginterferon alfa-2b is no longer being manufactured for sale in Canada. This article is being kept available for reference purposes only. If you are using this medication, speak with your doctor or pharmacist for information about your treatment options.

Peginterferon alfa-2b belongs to the group of medications known as interferons. It is used to treat chronic hepatitis C (a disease of the liver) for people who cannot tolerate or use the antiviral medication, ribavirin. The most effective treatment of chronic hepatitis C is the combination of an interferon and ribavirin. Peginterferon alfa-2b works by helping the immune system fight the hepatitis C virus, and by making it harder for the virus to reproduce within the body.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are being given this medication, speak to your doctor. Do not stop using 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?

Unitron Peg is no longer being manufactured for sale in Canada and is no longer available under any brand names. This article is being kept available for reference purposes only. If you are using this medication, speak with your doctor or pharmacist for information about your treatment options.

How should I use this medication?

Peginterferon alfa-2b is usually injected under the skin once weekly on the same day of the week for 48 weeks. Dosing is based on body weight. Treatment with this medication should be stopped if no response is noticed after 6 months.

If you are giving yourself injections, it is very important that you very carefully follow your health care professional's directions and the instructions included with the medication. After the medication has been mixed, it should be used right away and no longer than 3 hours after mixing (if mixing at home). Do not use this medication if it is discoloured.

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 using the medication without consulting your doctor.

It is important to use this medication exactly as prescribed by your doctor. If you miss a dose, administer it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not administer 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.

Store this medication in the refrigerator and keep it out of the reach of children. Do not freeze or shake the medication.

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?

Peginterferon alfa-2b should not be used by anyone who:

  • is allergic to peginterferon alfa-2b, any other interferon, or to any of the ingredients of the medication
  • has decompensated liver disease
  • has epilepsy (seizures)
  • has or has had autoimmune diseases (including autoimmune hepatitis)
  • has or has had severe psychiatric conditions
  • has severely reduced kidney function
  • has thyroid disease, when medication cannot bring thyroid function into the normal range

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.

  • decreased desire for sexual activities
  • drowsiness
  • dry mouth
  • dry skin
  • flu-like symptoms (unusual tiredness, fever, chills, muscle aches, joint pain and headaches)
  • flushing of the skin
  • indigestion
  • loss of appetite
  • nausea
  • pain in bones, joints, or muscles
  • redness, swelling, bruising, irritation, or itching at place of injection
  • temporary hair loss
  • trouble sleeping
  • vomiting
  • weight changes (loss or gain)

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

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

  • abdominal pain or swelling
  • anemia (paleness, tiredness, shortness of breath)
  • changes in mood (e.g., irritability, depression, anxiety, aggression)
  • confusion
  • dizziness
  • eye pain or swelling of the eye
  • high blood sugar (increased thirst, hunger, weakness, drowsiness, blurred vision, weight loss)
  • low blood sugar (headache, hunger, weakness, irritability, trouble concentrating)
  • lower back or side pain
  • signs of infection (e.g., chills, fever, cough, sore throat, difficulty or painful urination, difficulty breathing)
  • tingling or burning sensation in arms or legs
  • ulcers or sores in the mouth or throat
  • unusual bruising or bleeding (e.g., bleeding gums, nosebleeds, blood in the urine, pinpoint-sized red spots on skin)
  • vision changes (e.g., blurred vision, vision loss)
  • worsening psoriasis

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

  • fast or irregular heartbeat (palpitations)
  • severe skin rash (blistering, peeling, and spreading)
  • suicidal feelings or suicide attempt(s)
  • symptoms of a heart attack (e.g., severe chest pain or pressure, pain in the arm or shoulder, nausea, sweating)
  • symptoms of a severe allergic reaction (e.g., hives; difficulty breathing; swelling of the face, mouth, throat, or tongue)
  • symptoms of a stroke (e.g., sudden and severe headache, sudden weakness or numbness in the arms or legs, sudden vision changes, sudden dizziness)

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.

Allergic reactions: In rare cases, this medication may cause severe allergic reactions. If you notice hives, swelling of the face or throat, or difficulty breathing, stop using this medication and get medical help immediately.

Autoimmune conditions: This medication may cause or worsen autoimmune conditions including myositis, hepatitis, immune thrombocytopenic purpura (ITP), rheumatoid arthritis, interstitial nephritis, thyroiditis, and systemic lupus erythematosus. If psoriasis appears, the medication may need to be discontinued.

Blood glucose (sugar): This medication can cause low or high blood sugar. People with diabetes should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. If you experience high blood sugar (increased thirst, hunger, weakness, drowsiness, blurred vision, weight loss) or low blood sugar (headache, hunger, weakness, irritability, trouble concentrating) while taking this medication, contact your doctor.

Blood problems: This medication may suppress bone marrow function and cause blood problems such as low platelet counts, low white blood cell counts, and anemia. Your doctor will monitor you for these problems with blood tests. If you experience persistent fever and chills, tiredness, shortness of breath, or easy bruising or bleeding, contact your doctor.

Colon disorders: This medication may cause certain types of colitis. Report any stomach or abdominal pain, bloody diarrhea, or fever to your doctor immediately.

Depression and other psychiatric disorders: This medication can cause depression and other psychiatric conditions. People with psychiatric conditions should be closely monitored by their doctor while using this medication, as it may worsen these conditions. If you have or had a severe psychiatric condition, you should not take this medication. If you feel unusual sadness or hopelessness, or experience other behaviour or mood changes, contact your doctor immediately.

Drowsiness/reduced alertness: This medication may cause drowsiness or confusion. If the medication affects you in this way, avoid driving, operating machinery, or other tasks that require alertness.

Ear disorders: Certain ear disorders and hearing loss have been observed in people treated with this medication. If you experience any changes in your hearing while taking this medication, contact your doctor.

Eye disorders: Certain eye disorders have been observed in people treated with this medication. If you experience any changes in vision while taking this medication, contact your doctor.

Fertility: This medication may affect fertility. Some women have reported changes in their menstrual cycle when using this medication. If you experience any changes in your menstrual cycle while using this medication, contact your doctor.

Flu-like symptoms: This medication may cause a flu-like reaction, with aching muscles, fever, chills, and headache. Your doctor may prescribe acetaminophen before each dose of this medication and as needed to help reduce these symptoms.

Fluids: This medication may cause dehydration. People taking this medication should drink adequate fluids, especially on hot days or when exercising.

HCV/HIV/HBV: The safety and effectiveness of this medication have not been established for people with hepatitis C (HCV), who are also infected with human immunodeficiency virus (HIV) and hepatitis B virus (HBV).

Heart disease: This medication as well as others like it can cause heart problems such as high blood pressure, chest pain, heart attack, abnormal heart rhythms, and heart failure. People who have had a heart attack, heart failure, or changes in heart rhythm (arrhythmias) should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. People who have had severe, unstable, or uncontrolled heart disease within the past 6 months should not use this medication.

Kidney disease: People with kidney disease should have their kidney function assessed regularly while taking this medication. For people with reduced kidney function, their doctor may prescribe a lower dose. People who have severely reduced kidney function should not take this medication.

Liver function: People who are taking this medication will need frequent checkups to test their liver function. People with severely reduced liver function should not take this medication.

Lung disorders: Certain lung disorders may occur in people using this medication. If you experience fever, cough, or shortness of breath, contact your doctor. People who have chronic obstructive pulmonary disease- COPD (e.g., emphysema, chronic bronchitis) should not take this medication.

Pancreatitis: This medication may cause pancreatitis, which may be fatal. If you develop symptoms of pancreatitis (e.g., severe abdominal with or without vomiting), get immediate medical attention.

Thyroid disorders: This medication can cause or worsen hypothyroidism (low thyroid) or hyperthyroidism (high thyroid). People with thyroid conditions should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Transplants: The safety and effectiveness of using this medication have not been established for people who have had a liver or other organ transplant.

Triglycerides: This medication can cause or increase high triglyceride levels in the blood. Your doctor will check your triglyceride levels while you are taking this medication.

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. Women who may become pregnant should use an effective method of birth control while using peginterferon alfa-2b.

Breast-feeding: It is not known if peginterferon alfa-2b passes into breast milk. Breast-feeding must be stopped before starting this medication..

Children and adolescents: The safety and effectiveness of using this medication have not been established for children less than 18 years of age.

What other drugs could interact with this medication?

There may be an interaction between peginterferon alfa-2b and any of the following:

  • aldesleukin
  • telbivudine
  • theophylline

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.