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Other drug names: A-Am An-Az B C-Ch Ci-Cz D-Dh Di-Dz E F G H I-J K-L M-Mh Mi-Mz N-Nh Ni-Nz O P-Pl Pm-Pz Q-R S-Sn So-Sz T-To Tp-Tz U-V W-Z 0-9   

Peginterferon Alfa–2a (Systemic)

Brand Names

In the U.S.-

  • Pegasys


  • Biological response modifier


Peginterferon alfa-2a (peg in-ter-FEER-on alf-a 2a) is a synthetic (man-made) version of substances normally produced in the body to fight infection. Peginterferon alfa-2a is used to treat chronic hepatitis C. It is used for patients who have never been treated by alpha interferons.

This medicine is available only with your doctor's prescription, in the following dosage forms:

  • Injection (U.S.)

Before Using This Medicine

In deciding to use a medicine, the risks of using peginterferon alfa-2a must be weighed against the good it will do. This is a decision you and your doctor will make. For peginterferon alfa****�, the following should be considered:

Allergies- Tell your doctor if you have ever had any unusual or allergic reaction to peginterferon alfa****�. Also tell your doctor and pharmacist if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy- Peginterferon alfa-2a has not been studied in pregnant women. However, studies in animals have shown that peginterferon alfa-2a causes pregnancy losses. This medicine should only be given to fertile women if they are using a proven form of birth control. Patients using peginterferon alfa-2a should assume that it is dangerous to pregnant women and their babies

Breast-feeding- It is not known if peginterferon alfa-2a passes into breast milk. It is sometimes dangerous to use medicines while breast feeding. Mothers who are taking this medicine and who wish to breast-feed should discuss this with their doctor. A decision must be made whether to stop breast-feeding or to stop using peginterferon alfa-2a.

Children- Studies of this medicine have been done only in adult patients and there is no specific information comparing use of peginterferon alfa****� in children with use in other age groups. However, this medicine should not be used in newborns and infants because it has a substance that is harmful to newborns and infants.

Older adults- Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of peginterferon alfa****� in the elderly with use in other age groups.

Other medicines- Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking peginterferon alfa 2a, it is especially important that your doctor and pharmacist know if you are taking any of the following:

  • Didanosine (e.g., Videx)-There have been reports of severe side effects when this medicine is taken at the same time as peginterferon alfa-2a
  • Ribavirin (e.g., Virazole)- People are required to use two types of birth control when this medicine is taken at the same time as peginterferon alfa-2a
  • Theophylline (e.g., Slo-bid, Theodur, Uniphyl)-The effects of this medicine may be increased when it is taken with peginterferon alfa****�

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your health care professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

Other medical problems- The presence of other medical problems may affect the use of peginterferon alfa****�. Make sure you tell your doctor if you have any other medical problems, especially:
  • Autoimmune hepatitis (serious liver disease)-peginterferon alfa-2a should not be used if you have this disease
  • Anemia (blood disease) or
  • Blood problems- peginterferon alfa-2a may make these conditions worse and your doctor may have you take a lower dose of this medicine
  • Bone marrow illness- peginterferon alfa-2a may make these conditions worse
  • Lung or breathing problems-peginterferon alfa-2a may make these conditions worse
  • Diabetes mellitus (sugar diabetes) or
  • Hyperglycemia (high blood sugar) or
  • Hypoglycemia (low blood sugar) or
  • Hyperthyroidism (overactive thyroid gland) or
  • Hypothyroidism (underactive thyroid gland)-this medicine should be used with caution in patients with these conditions; if your condition is not well controlled with your medicine you should not start using peginterferon alfa-2a
  • Heart problems- peginterferon alfa-2a should be with caution in people with heart problems
  • HIV (human immunodeficiency virus) or
  • Hepatitis B virus (liver disease caused by a virus)- it is unclear how well this medicine works and how safe this medicine is when a patient has these conditions
  • Infections (serious infections caused by bacteria)- peginterferon alfa-2a therapy should be stopped in patients who have serious infections
  • Interstitial nephritis (kidney inflammation) or
  • Myositis (muscular pain) or
  • Psoriasis (skin disease) or
  • Rheumatoid arthritis or
  • Systemic Lupus (connective tissue disease) or
  • Thyroiditis (thyroid gland problem)-peginterferon alfa-2a may make these conditions worse and it should be used with caution in patients who have these conditions
  • Kidney failure-the dose of peginterferon alfa-2a may need to be lower for patients who have this condition
  • Depression or
  • Mental illness-peginterferon alfa-2a should be used with caution in patients with these conditions
  • Organ transplants-it is not known if this medicine is safe to use in patients who have recently had organ transplants.

Proper Use of This Medicine


The dose of peginterferon alfa-2a will be different for different patients. Follow your doctor's orders or the directions on the label . The following information includes only the average doses of peginterferon alfa-2a If your dose is different, do not change it unless your doctor tells you to do so.

The length of time you take the medicine depends on the medical problem for which you are taking peginterferon alfa-2a

  • For parenteral dosage form (injection):
    • For chronic hepatitis C:
      • Adults-180 micrograms once weekly for 24 to 48 weeks
      • Children-This medicine is not usually used in children under the age of 18

Missed dose-

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


To store this medicine:

  • Keep out of the reach of children.
  • Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
  • Store in the refrigerator. However, keep the medicine from freezing.
  • Do not keep outdated medicine or medicine no longer needed. Ask your health care professional how you should dispose of any medicine you do not use. Be sure that any discarded medicine is out of the reach of children.

Precautions While Using This Medicine

This medicine may cause some people to become drowsy, dizzy, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy and not alert.

It is very important that your doctor check your progress at regular visits. This will allow your doctor to see if the medicine is working properly and to check for any problems that this medicine may cause.

Side Effects of This Medicine

Side Effects of This Medicine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

  • More common
    • black, tarry, stools;  chills ;  cough;  discouragement;  feeling sad or empty;  fever;  irritability ;  lack of appetite ;  loss of interest or pleasure ;  lower back or side pain;  painful or difficult urination ;  pale skin;  shortness of breath;  sore throat;  tiredness ;  trouble concentrating ;  trouble sleeping;  ulcers, sores, or white spots in mouth;  unusual bleeding or bruising ;  unusual tiredness or weakness 

  • Less common
    • bone pain;  chest pain or discomfort ;  confusion;  constipation ;  depressed mood;  difficult urination;  dizziness;  dry skin and hair;  fainting;  fast heartbeat;  feeling cold ;  hair loss;  headache;  heart murmur;  hoarseness or husky voice ;  lightheadedness;  muscle cramps and stiffness ;  pale skin;  rapid, shallow breathing;  slowed heartbeat;  sneezing;  stomach pain;  tightness in chest;  troubled breathing with exertion ;  unusual bleeding or bruising;  unusual tiredness or weakness;  wheezing;  weight gain 

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome.

  • More Common
    • back pain;  blistering, crusting, irritation, itching, or reddening of skin; cracked, dry, scaly skin;  diarrhea;  dry mouth;  fear ;  feeling unusually cold, shivering;  fever;  hair loss or thinning;  muscle or joint pain;  nervousness;  numbness;  pain;  rash;  redness ;  scarring ;  soreness;  stinging;  stomach pain;  swelling;  tenderness ;  tingling;  ulceration;  vomiting;  warmth 

  • Less common
    • acid or sour stomach;  belching ;  blurred vision;  heartburn ;  indigestion ;  memory problems;  stomach discomfort upset or pain 

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

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Last updated: Tue, 06 Jan 2009 00:20:03 GMT