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Drugs reference index «Peginterferon alfa-2a»

Peginterferon alfa-2a

Peginterferon alfa-2a

Brand names: Pegasys

Why is Peginterferon alfa-2a prescribed?

Pegasys is used to treat adults who have chronic hepatitis C infection, including those who are also infected with HIV and are clinically stable. Additionally, the drug is used to treat hepatitis B. Pegasys is an injection prescribed for people who show signs of liver damage and have not been previously treated with alpha interferon.

Pegasys is a synthetic (man-made) version of interferon, a substance normally produced in the body to fight various infections, including the virus that causes hepatitis. Pegasys can be taken alone (for hepatitis B or C) or in combination with ribavirin (for hepatitis C). Ribavirin works with interferon to help your body get rid of the hepatitis C virus and prevent it from coming back. Treatment with ribavirin alone, however, is not effective against hepatitis C.

Most important fact about Peginterferon alfa-2a

Pegasys, taken alone or combined with ribavirin, can have serious side effects that may cause death in rare cases (see "Special warnings about Peginterferon alfa-2a"). Combining Pegasys with ribavirin can induce anemia severe enough to cause a heart attack, especially in people who already have heart disease. Before using Pegasys, you should talk with your doctor about the possible benefits and side effects of treatment. Once you start taking Pegasys, you will need to see your doctor regularly for exams and blood tests to make sure the treatment is working and to check for side effects.

In addition, combination treatment with Pegasys and ribavirin can cause death, serious birth defects, or other harm to an unborn baby. Female patients and female partners of male patients being treated with Pegasys and ribavirin must have a pregnancy test before treatment begins and then monthly during treatment to prove they are not pregnant. Both women and men must use two effective forms of birth control during combination therapy and for 6 months after stopping the drugs. Men should use a condom with spermicide as one of the two forms.

How should you take Peginterferon alfa-2a?

Pegasys is given by injection under the skin. It should be taken once a week, on the same day each week and around the same time. Your doctor will train you or your caregiver on the best way to give the injection.

Pegasys comes in two forms: a liquid in a single-use vial and a liquid in a prefilled syringe. Your doctor will determine which is best for you. Be sure to inspect the medication before injecting it. If you see floating particles or the medication is discolored, do not use it.

Your doctor will also decide whether you should take Pegasys with ribavirin, which comes in tablet form. If the doctor prescribes ribavirin, you should take it twice a day with food (breakfast and dinner).

Drink plenty of fluids and avoid dehydration while taking Pegasys, especially during the beginning of treatment.

  • If you miss a dose...If it is within 2 days of when you should have taken Pegasys, give the injection as soon as you remember. Take your next dose on the day you would usually take it. If more than 2 days have passed, ask your doctor what to do.

If you miss a dose of ribavirin, take the forgotten dose as soon as you remember. However, if it is almost time for your next dose, skip the one you missed and return to your regular schedule. Do not take two doses at once.

  • Storage instructions...Store Pegasys in the refrigerator at a temperature of 36 to 46 degrees Fahrenheit. Keeping Pegasys at temperatures outside the recommended range can destroy the medicine. Do not leave Pegasys outside of the refrigerator for more than 24 hours.

Do not freeze or shake the medication; also protect it from light.

What side effects may occur?

Side effects cannot be anticipated. If any develop or change in intensity, tell your doctor as soon as possible. Only your doctor can determine if it is safe to continue using Pegasys.

  • Side effects may include:Anxiety, depression, diarrhea, flu-like symptoms (chills, fatigue, fever, headache, muscle pain), hair thinning, insomnia, irritability, itchy spots, joint pain, loss of appetite, nausea and vomiting, skin reactions (especially at the injection site), weight loss

Why should Peginterferon alfa-2a not be prescribed?

Do not take Pegasys if you:

  • Have ever had an allergic reaction to another alpha interferon drug or to any of the ingredients in Pegasys
  • Have hepatitis caused by your immune system attacking your liver (autoimmune hepatitis)
  • Have unstable or severe liver disease

Do not take Pegasys combined with ribavirin if you:

  • Have ever had an allergic reaction to ribavirin or to any of the ingredients in the drug
  • Are pregnant or planning to become pregnant during treatment or during the 6 months after treatment has ended, or if you're breastfeeding. If you're a man and have a female partner who fits these criteria, you must also avoid combination therapy.
  • Have a disorder that affects the red blood cells, such as sickle-cell anemia or thalassemia major

Special warnings about Peginterferon alfa-2a

Pegasys should be used with extreme caution in people who have a history of severe mental illness, especially depression or anxiety, or those with a history of drug or alcohol addiction. Possible side effects of the drug include irritability, aggressive behavior, anxiety, depression, and suicidal thoughts. A few individuals have committed suicide while using Peginterferon alfa-2a. In addition, people formerly addicted to drugs or alcohol could have a relapse while taking Pegasys.

Other serious—and possibly life-threatening—side effects of treatment include:

  • Blood disorders that could increase the risk of serious infection or bleeding
  • Infections, including ones that have caused death
  • Lung problems, such as difficulty breathing or pneumonia
  • Eye problems, including blurred vision or loss of vision
  • Autoimmune disorders, including psoriasis, systemic lupus erythematosus, and thyroid problems
  • Heart problems, including chest pain and, very rarely, heart attack
  • Liver problems
  • Colitis (inflammation of the bowel). Symptoms include abdominal pain, bloody diarrhea, and fever.
  • Severe allergic reactions, including rash, hives, and difficulty breathing

Combination treatment with ribavirin can also cause severe side effects, including:

  • Birth defects or death of an unborn baby
  • Decrease in red blood cells (anemia). This is especially dangerous in people who already have heart disease or circulatory problems.
  • Pancreatitis (inflammation of the pancreas). Symptoms include severe pain in the upper abdomen, diarrhea, weight loss, nausea and vomiting, and fever.

Before taking Pegasys (with or without ribavirin), tell your doctor if you've ever had any of the following: history of heart disease or heart attack; history of cancer; autoimmune disorders such as psoriasis, systemic lupus erythematosus, or rheumatoid arthritis; kidney problems; blood disorders; diabetes; thyroid problems; liver problems other than hepatitis C; hepatitis B infection; an organ transplant; or colitis (inflammation of the bowel).

Contact your doctor immediately if you develop any of these symptoms while taking Pegasys: depression or suicidal thoughts, severe chest pain, difficulty breathing, vision changes, unusual bleeding or bruising, high or persistent fever, severe stomach or lower back pain, or bloody diarrhea. Also alert the doctor if you have psoriasis that gets worse while taking Peginterferon alfa-2a.

It is not known whether Pegasys, either alone or combined with ribavirin, can permanently eliminate the hepatitis C virus or prevent liver cancer or liver failure caused by hepatitis C infection. It is also not known whether treatment can prevent you from infecting another person with the virus.

Pegasys may cause dizziness, confusion, sleepiness, or fatigue. Avoid driving or operating dangerous machinery until you know how Peginterferon alfa-2a affects you.

Possible food and drug interactions when taking Peginterferon alfa-2a

If you are taking didanosine, combination treatment with Pegasys and ribavirin is not recommended. Serious and even fatal reactions have occurred.

If Pegasys is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Pegasys (either alone or combined with ribavirin) with the following:

HIV drugs known as nucleoside analoguesMethadoneTheophylline

In addition, tell the doctor if you are taking or planning to take other prescription medicines, over-the-counter medicines, or vitamin, mineral, or herbal supplements.

Special information if you are pregnant or breastfeeding

You must not become pregnant or nurse a baby during combination treatment with Pegasys and ribavirin (see "Most important fact about Peginterferon alfa-2a"). This also applies to female partners of men who are taking the drugs.

Recommended dosage for Peginterferon alfa-2a


Your doctor will determine the best dose based on your condition and how your body responds to the drug. If you develop severe side effects, your dosage may need to be reduced or stopped altogether.

The safety and effectiveness of long-term treatment with Pegasys (more than a year) have not been studied.


If you take more than the prescribed amount of Pegasys, call your doctor immediately. You may need to have an exam or blood test to check for adverse reactions.

  • Symptoms of overdose may include:Blood disorders, fatigue, liver problems
  • Peginterferon Alfa-2a Professional Patient Advice (Wolters Kluwer)
  • peginterferon alfa-2a Subcutaneous Advanced Consumer (Micromedex) - Includes Dosage Information
  • Peginterferon Alfa-2a MedFacts Consumer Leaflet (Wolters Kluwer)
  • Pegasys Prescribing Information (FDA)
  • Pegasys Consumer Overview