What is this medication for?
Peginterferon alfa-2a belongs to the group of medications known as interferons. It is used to treat chronic hepatitis B and chronic hepatitis C, which are diseases of the liver, by people who have not previously been treated with interferon alfa. Peginterferon alfa-2a works by helping the immune system fight the hepatitis B and 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 here. As well, some forms of this medication may not be used for all of the conditions discussed here. If you 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® is available as:
- injectable (prefilled syringe)
- injectable (single use vial)
Some medications may have other generic brands available. Always ask your doctor or pharmacist about the safety of switching between brands of the same medication.
How should I use this medication?
The usual dose of peginterferon alfa-2a is 180 µg (micrograms) once weekly for a period of 48 weeks. If there is no improvement after 12 weeks of use, your doctor may stop the treatment. This medication is usually injected subcutaneously (under the skin) in the abdomen or thigh.
If you are giving yourself the 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.
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 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, protect it from light and moisture, and keep it out of the reach of children. Do not freeze or shake the medication.
Who should NOT take this medication?
Peginterferon alfa-2a should not be used by anyone who:
- is allergic to peginterferon alfa-2a or any other interferon, to E. coli-derived products, or to any of the ingredients of the medication
- is pregnant or has a partner who is pregnant
- is an infant
- has a hemoglobinopathy (e.g., thalassemia major, sickle-cell anemia)
- has autoimmune hepatitis
- has decompensated cirrhosis
- has HIV-HCV with cirrhosis and a baseline Child-Pugh score ≥6