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Pegasys

Generic Name: peginterferon alfa-2a (peg in ter FEER on AL fa 2 a)
Brand Names: Pegasys

Medically reviewed by Philip Thornton, DipPharm. Last updated on Aug 12, 2020.

What is Pegasys?

Pegasys (peginterferon alfa-2b) is made from human proteins that help the body fight viral infections.

Pegasys is used alone or with other medicines to treat chronic hepatitis C in adults and children at least 5 years old.

Pegasys is also used to treat chronic hepatitis B when the virus begins to damage the liver in adults and children at least 3 years old.

Important Information

You should not use Pegasys if you have liver failure or autoimmune hepatitis.

You should not use Pegasys with ribavirin if you are pregnant, or if you are a man whose sex partner is pregnant. Use effective birth control to prevent pregnancy while taking ribavirin and for at least 6 months after your last dose.

Pegasys may cause serious or fatal side effects.

Tell your doctor about any new or worsening mood symptoms, such as feeling irritable, hostile, aggressive, depressed, or having thoughts about suicide or hurting yourself.

Call your doctor right away if you have symptoms such as chest pain, fast heartbeats, trouble breathing, numbness or weakness, vision or speech problems, fever, chills, a cough with mucus, burning when you urinate, or bloody diarrhea.

Before taking this medicine

You should not use Pegasys if:

  • you are allergic to any type of interferon alfa; or

  • you have autoimmune hepatitis, or severe liver damage.

When taking Pegasys with other medicine: To make sure all medicines are safe for you, tell your doctor about all your medical conditions, and if you are pregnant or breastfeeding.

To make sure Pegasys is safe for you, tell your doctor if you have ever had:

Pegasys may contain an ingredient that can cause serious side effects or death in very young or premature babies. Do not give this medicine to a child younger than 1 year old.

You may need to have a negative pregnancy test before starting this treatment.

Pegasys is sometimes used in combination with ribavirin. Both men and women using ribavirin should use effective birth control to prevent pregnancy. Ribavirin can cause birth defects, miscarriage, or death to an unborn baby if the mother or father is using Pegasys.

You should not take ribavirin if you are pregnant, or if you are a man and your sex partner is pregnant. Use effective birth control to prevent pregnancy. Keep using birth control for at least 6 months after your last dose of ribavirin.

Tell your doctor right away if a pregnancy occurs while either the mother or the father is using ribavirin.

You should not breastfeed while using Pegasys. Women with HIV or AIDS should not breastfeed a baby. Even if your baby is born without HIV, the virus may be passed to the baby in your breast milk.

How should I use Pegasys?

Use Pegasys exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets.

Pegasys is injected under the skin, usually once per week on the same day each week. A healthcare provider may teach you how to properly use the medication by yourself.

Read and carefully follow any Instructions for Use provided with your medicine. Ask your doctor or pharmacist if you don't understand all instructions.

Prepare a Pegasys injection only when you are ready to give it. Do not use if the medicine looks cloudy, has changed colors, or has particles in it. Call your pharmacist for new medicine.

Peginterferon alfa-2a doses are based on body surface area (height and weight) in children. Your child's dose needs may change if the child is still growing.

Your dose needs may change if you switch to a different brand, strength, or form of this medicine. Avoid medication errors by using only the form and strength your doctor prescribes.

You will need frequent medical tests. Your vision and lung function may also need to be checked.

Each Pegasys vial (bottle), prefilled syringe, or auto-injector device is for one use only. Throw it away after one use, even if there is still medicine left inside.

Store in the refrigerator, protected from light. Do not shake or freeze this medicine.

Follow the package directions about letting your medicine reach room temperature before injecting your dose. Do not leave the medicine out of a refrigerator for longer than 24 hours.

Use a needle and syringe only once and then place them in a puncture-proof "sharps" container. Follow state or local laws about how to dispose of this container. Keep it out of the reach of children and pets.

Pegasys dosing information

Usual Adult Dose of Pegasys for Chronic Hepatitis C:

PATIENTS WITHOUT HIV COINFECTION:
Combination Therapy:
-HCV genotypes 1, 2, 3, 4: 180 mcg subcutaneously once a week
-HCV genotypes 5, 6: Insufficient data for dosing recommendations

Duration of therapy when used with other HCV antiviral drugs:
-HCV genotypes 1, 2, 3, 4: The manufacturer product information of the other HCV antiviral drugs should be consulted.

Duration of therapy when used with ribavirin without other HCV antiviral drugs:
-HCV genotypes 1, 4: 48 weeks
-HCV genotypes 2, 3: 24 weeks

Monotherapy: 180 mcg subcutaneously once a week for 48 weeks

Discontinuation of Therapy for HCV Genotype 1 (when used with ribavirin or alone):
-Therapy should be discontinued if there is not at least a 2 log10 reduction from baseline in HCV RNA by 12 weeks of therapy or if HCV RNA remains detectable after 24 weeks of therapy.
-The manufacturer product information for specific coadministered HCV antiviral drugs should be consulted for information on discontinuation based on treatment response.

PATIENTS WITH HIV COINFECTION:
Combination Therapy: 180 mcg subcutaneously once a week

Duration of therapy:
-When used with other HCV antiviral drugs: The manufacturer product information of the other HCV antiviral drugs should be consulted.
-When used with ribavirin without other HCV antiviral drugs: 48 weeks, regardless of HCV genotype

COMMENTS:
-The manufacturer product information for coadministered HCV antiviral drugs should be consulted.
-This drug should not be used alone or in combination with ribavirin without additional HCV antiviral drugs for treatment of chronic hepatitis C (CHC) patients who failed prior interferon alfa therapy.
-This drug is not recommended for treatment of CHC patients who have had solid organ transplantation.
-Therapy should be discontinued at once if hepatic decompensation occurs.

USE: For the treatment of CHC patients (with or without HIV coinfection) with compensated liver disease
-As part of a combination regimen with other HCV antiviral drugs
-As monotherapy if contraindications or significant intolerance to other HCV antiviral drugs

Usual Adult Dose of Pegasys for Chronic Hepatitis B:

180 mcg subcutaneously once a week for 48 weeks

Use: For the treatment of patients with HBeAG-positive and HBeAG-negative chronic hepatitis B who have compensated liver disease and evidence of viral replication and liver inflammation

Usual Pediatric Dose of Pegasys for Chronic Hepatitis C:

5 years or older: 180 mcg/1.73 m2 x BSA subcutaneously once a week
Maximum dose: 180 mcg

Duration of therapy:
-HCV genotypes 2, 3: 24 weeks
-Other HCV genotypes: 48 weeks

Comments:
-For use with ribavirin
-The manufacturer product information for ribavirin should be consulted.
-Patients who start therapy before their 18th birthday should remain on the recommended pediatric dose until therapy is finished.

Use: In combination with ribavirin, for the treatment of CHC patients with compensated liver disease

What happens if I miss a dose?

Use the medicine as soon as you remember, and then go back to your regular injection schedule. Do not use two doses at one time.

If you are more than 2 days late in using your injection, call your doctor for instructions.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while using Pegasys?

Avoid drinking alcohol. It may increase your risk of liver damage.

Avoid driving or hazardous activity until you know how Pegasys will affect you. Your reactions could be impaired.

Using Pegasys ay not prevent your disease from spreading. Follow your doctor's instructions about how to prevent passing the disease to another person.

Pegasys side effects

Get emergency medical help if you have signs of an allergic reaction to Pegasys (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Peginterferon alfa-2a can cause life-threatening infections, autoimmune disorders, serious mood or behavior problems, or a stroke.

Call your doctor at once if you have unusual changes in mood or behavior, such as: depression, irritability, aggression, hallucinations, thoughts about hurting yourself, or falling back into a previous pattern of drug addiction.

Peginterferon alfa-2a may cause serious or fatal side effects. Call your doctor at once if you have:

  • severe stomach pain with bloody diarrhea;

  • new or worsening cough, cough with yellow or pink mucus, trouble breathing;

  • numbness, tingling, or burning in your arms or legs;

  • pain or burning when you urinate;

  • sudden numbness or weakness, slurred speech, problems with balance;

  • vision changes;

  • low blood cell counts - fever, chills, tiredness, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath;

  • high or low blood sugar - headache, hunger, confusion, sweating, thirst, increased urination, weakness, fruity breath odor, feeling anxious or shaky, weight loss, or fainting;

  • pancreatitis - severe pain in your upper stomach spreading to your back, nausea and vomiting;

  • thyroid problems - weight changes, skin changes, trouble concentrating, feeling hot or cold all the time; or

  • worsening liver symptoms - swelling around your midsection, nausea, diarrhea, loss of appetite, confusion, drowsiness, yellowing of the skin or eyes, loss of consciousness.

Your next injection may be delayed if you have certain side effects.

Pegasys can affect growth in children. Tell your doctor if your child is not growing at a normal rate while using this medicine.

Common Pegasys side effects may include:

  • fever, chills;

  • muscle or joint pain;

  • headache; or

  • feeling weak or tired.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Pegasys?

Tell your doctor about all your other medicines, especially:

This list is not complete. Other drugs may interact with peginterferon alfa-2a, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Pegasys only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.