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

This medication is a combination of two different medications: peginterferon alfa-2a and ribavirin. Peginterferon alfa-2a belongs to the group of medications known as interferons. Ribavirin belongs to the group of medications known as antivirals. This combination medication is used to treat certain forms of chronic hepatitis C, which is a disease of the liver. It works by helping the immune system fight the hepatitis C virus, and by making it harder for the virus to reproduce within the body.

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 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?

Pegasys RBV (Pegasys and Copegus) 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.

How should I use this medication?

This medication is available as a package containing ribavirin tablets and peginterferon alfa-2a injections. The ribavirin tablets are taken in combination with the peginterferon alfa-2a injections.

Peginterferon alfa-2a injection: The usual dose of peginterferon alfa-2a is 180 µg (micrograms) once weekly for a period of 24 or 48 weeks. This medication is usually injected under the skin (subcutaneously) in the abdomen or thigh area. Do not use the injection if it is discoloured or if particles are present.

Ribavirin tablets: The usual daily dose of ribavirin is 800 mg, 1,000 mg, or 1,200 mg in 2 divided doses, taken morning and evening with food for 24 or 48 weeks. The dose and duration of treatment depend on your condition and may depend on body weight.

If there is no improvement after 12 weeks of use, your doctor may stop treatment.

Dose adjustments may be needed if certain side effects are experienced or for certain medical conditions.

If you are giving yourself the injections, it is very important that you carefully follow your health care professional's directions and the instructions included with the medication.

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 using the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor.

If you miss a dose of peginterferon alfa-2a and remember within 2 days of the scheduled dose, give the dose as soon as possible. If more than 2 days have passed, check with your doctor for further instructions. If you miss a dose of ribavirin, take the missed dose 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 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.

Store the packages, vials, or prefilled syringes in the refrigerator, protect them from light, and keep them out of the reach of children. Do not freeze, shake, or use them past the expiry date. Store the ribavirin tablets at room temperature or in the refrigerator and keep them 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 use peginterferon alfa-2a - ribavirin if you:

  • are allergic to peginterferon alfa-2a, ribavirin, or any ingredients of the medication
  • are allergic to other interferons, E. coli-derived products
  • are breast-feeding
  • are pregnant or have a pregnant partner
  • have decompensated liver disease
  • have blood disorders(e.g., anemia, thalassemia, sickle-cell anemia)
  • have HIV-HCV (human immunodeficiency virus and hepatitis C virus) with cirrhosis and a baseline Child-Pugh score greater than or equal to 6
  • have or have had a severe psychiatric disorder
  • have or have had autoimmune diseases (including autoimmune hepatitis)
  • have or have had thyroid problems not controlled by medication

Do not give this medication to infants.

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.

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

Although most of these 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 bowel inflammation (e.g., fever that appears after starting the medication, watery and severe diarrhea [may also be bloody])
  • 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, loss of vision)
  • 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.

Anemia: Interferon alfa-2a may cause low levels of red blood cells. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, feeling unusually tired or pale skin, contact your doctor as soon as possible.

Your doctor will do blood tests regularly to monitor the number of specific types of blood cells, including red blood cells, in your blood.

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.

Bleeding: Interferon alfa-2a may cause a reduced number of platelets in the blood, which can make it difficult to stop cuts from bleeding. If you notice any signs of bleeding, such as frequent nosebleeds, unexplained bruising, or black and tarry stools, notify your doctor as soon as possible. Your doctor will order routine blood tests to make sure potential problems are caught early.

Blood glucose (sugar): This medication can cause low or high blood sugar. If you have diabetes, 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 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.

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 conditions: This medication can cause depression and other psychiatric conditions. If you have depression or a history of depression, 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 depression such as poor concentration, changes in weight, changes in sleep, decreased interest in activities, or notice them in a family member who is taking this medication contact your doctor as soon as possible.

Drowsiness/reduced alertness: People who develop dizziness, confusion, drowsiness, or fatigue while using this medication should not drive or operate machinery.

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

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

Fluids: This medication may cause dehydration. Make sure you drink enough fluids, especially on hot days or when exercising.

HCV/ HBV: The safety and effectiveness of this medication have not been established for people with hepatitis C (HCV), who are also infected with 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. If you have had a heart attack, heart failure, or changes in heart rhythm (arrhythmias), 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. People who have had severe, unstable, or uncontrolled heart disease within the past 6 months should not use this medication.

Infection: Interferon alfa-2a can reduce the number of cells that fight infection in the body (white blood cells). If possible, avoid contact with people with contagious infections. Tell your doctor immediately if you notice signs of an infection, such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness. Your doctor will do blood tests regularly to monitor the number of specific types of blood cells in your blood.

Kidney disease: This medication is not recommended for people with kidney disease. Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, 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 kidney problems develop while taking this medication, you may need to stop taking it.

Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. 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 want to test your liver function regularly with blood tests while you are taking this medication.

If you develop decreased liver function, you may require a lower dose of the medication or may need to stop taking it. Your doctor will do blood tests regularly to monitor your liver function. 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.

Lung disorders: Certain lung disorders may occur in people using this medication. If you experience fever, cough, or shortness of breath, contact your doctor. If you have chronic obstructive pulmonary disease (COPD; e.g., emphysema or chronic bronchitis) discuss the risks and benefits of using this medication with your doctor.

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.

Stroke: This medication has been associated with stroke. If you experience symptoms of a stroke (e.g., sudden and severe headache, sudden weakness or numbness in the arms or legs, sudden vision changes, sudden dizziness) while taking this medication, get immediate medical attention.

Thyroid disorders: This medication can cause or worsen hypothyroidism (low thyroid) or hyperthyroidism (high thyroid). If you have a thyroid condition, 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.

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

Pregnancy and contraception: The use of this medication is not recommended for pregnant women, as ribavirin may cause birth defects or the death of the fetus if it is used during pregnancy. Do not use this medication if you are pregnant or if your partner is pregnant.

Two forms of effective birth control (one for each partner) must be used during treatment and for 6 months after stopping therapy. During this time, women will have monthly pregnancy tests to ensure they are not pregnant. Tell your doctor immediately if you become pregnant while using this medication.

Breast-feeding: It is not known if peginterferon alfa-2a - ribavirin passes into breast milk. Due to the potential for serious harm to a baby if they are exposed to these medications, 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. This medication is not recommended for use by newborns or infants because peginterferon alfa-2a contains benzyl alcohol and may be harmful.

What other drugs could interact with this medication?

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

  • abacavir
  • aldesleukin
  • aminophylline
  • antacids containing aluminum or magnesium
  • azathioprine
  • Chinese herbal medicine (sho-saiko-to or Xiao Chai Hu )
  • clozapine
  • didanosine
  • emtricitabine
  • influenza vaccine
  • lamivudine
  • methadone
  • pegloticase
  • stavudine
  • telbivudine
  • tenofovir
  • 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.