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All Medications
Common brand names
- Pegasys
How it is administered
Pegylated interferon alfa-2a is given as a subcutaneous injection, which means it is injected under the skin, usually in the abdomen or thigh. It comes in a prefilled syringe or a vial for single use. The typical adult dose is 180 micrograms once weekly, but the exact dose and duration depend on the disease being treated and patient characteristics. Pediatric dosing is adjusted based on body surface area.
How it works
Pegylated interferon alfa-2a is a modified form of interferon, a protein that boosts the body's immune response. The 'pegylated' part means it has been attached to a molecule called polyethylene glycol, which helps it stay in the body longer and work more effectively with less frequent dosing.
This medication binds to specific receptors on the surface of cells and activates the immune system, leading to the production of proteins that help fight viruses and abnormal cells. While it is primarily approved for hepatitis B and C, it has also been used off-label for some blood cancers, including certain types of leukemia, because of its ability to suppress abnormal cell growth and modulate immune responses.
Common side effects
- Fatigue or weakness
- Fever and chills
- Muscle aches (myalgia)
- Headache
- Injection site reactions (redness, swelling, pain)
- Nausea and vomiting
- Loss of appetite
- Depression, irritability, or insomnia
- Hair thinning
- Flu-like symptoms
Other side effects may include changes in blood counts (such as low white cells or platelets), thyroid problems, and, rarely, more serious effects like infections, vision changes, or severe mood changes. Always report any unusual symptoms to your healthcare provider.
Who should take it
Pegylated interferon alfa-2a is FDA-approved for adults and some children with chronic hepatitis B or C. In the context of blood cancers, it may be used off-label for certain patients with chronic myeloproliferative disorders, such as some types of leukemia, when other treatments are not suitable or have not worked.
It is important that a healthcare provider evaluates whether this medication is appropriate, taking into account the specific diagnosis, overall health, and other medications being used.
Who should not take it
You should not take pegylated interferon alfa-2a if you have had severe allergic reactions to interferons or any of the ingredients in the medication. It is also contraindicated in patients with autoimmune hepatitis, severe liver disease (hepatic decompensation), or in neonates and infants due to the risk from benzyl alcohol in the formulation.
Women who are pregnant or planning to become pregnant should not use this medication, especially in combination with ribavirin, due to the risk of birth defects. Patients with certain psychiatric, heart, or autoimmune conditions should discuss risks carefully with their doctor.
Commonly used with
For hepatitis C, pegylated interferon alfa-2a is often used in combination with ribavirin and sometimes with other antiviral medications. In blood cancers, it may be used alone or with other treatments depending on the specific disease and patient needs.
If you are taking other medications, especially those that affect the immune system or blood counts, your doctor will monitor you closely for interactions.
Commonly tested with
Pegylated interferon alfa-2a has been tested in combination with ribavirin for hepatitis C and with lamivudine for hepatitis B. In the context of blood cancers, it may be studied with other agents used for myeloproliferative disorders, but always under close medical supervision.