|Trade names||Pegasys, others|
|Defined daily dose||26 mcg|
|AHFS/Drugs.com||Professional Drug Facts|
|Chemical and physical data|
|Molar mass||19241 g/mol (unpegylated)|
40000 g/mol (pegylated) g·mol−1
|(what is this?)|
Pegylated interferon alfa-2a, sold under the brand name Pegasys among others, is medication used to treat hepatitis C and hepatitis B. For hepatitis C it is typically used together with ribavirin and cure rates are between 24 and 92%. For hepatitis B it may be used alone. It is given by injection under the skin.
Side effects are common. They may include headache, feeling tired, depression, trouble sleeping, hair loss, nausea, pain at the site of injection, and fever. Severe side effects may include psychosis, autoimmune disorders, blood clots, or infections. Use with ribavirin is not recommended during pregnancy. Pegylated interferon alfa-2a is in the alpha interferon family of medications. It is pegylated to protect the molecule from breakdown.
Pegylated interferon alfa-2a was approved for medical use in the United States in 2002. It is on the World Health Organization's List of Essential Medicines. The wholesale cost in the developing world is between 500.00 and US$4,800.00 for 12 weeks. In the United States this costs about US$9,250.00, while in the United Kingdom 12 weeks costs the NHS about 1492.80 pounds.
This drug is approved around the world for the treatment of chronic hepatitis C (including people with HIV co-infection, cirrhosis, 'normal' levels of ALT) and has recently been approved (in the EU, U.S., China and many other countries) for the treatment of chronic hepatitis B. It is also used in the treatment of certain T-cell lymphomas, particularly mycosis fungoides.
Peginterferon alfa-2a is a long acting interferon. Interferons are proteins released in the body in response to viral infections. Interferons are important for fighting viruses in the body, for regulating reproduction of cells, and for regulating the immune system.
Host genetic factors
For genotype 1 hepatitis C treated with pegylated interferon alfa-2a or pegylated interferon alfa-2b combined with ribavirin, it has been shown that genetic polymorphisms near the human IL28B gene, encoding interferon lambda 3, are associated with significant differences in response to the treatment. This finding, originally reported in Nature, showed genotype 1 hepatitis C patients carrying certain genetic variant alleles near the IL28B gene are more likely to achieve sustained virological response after the treatment than others. Another report in Nature  demonstrated the same genetic variants are also associated with the natural clearance of the genotype 1 hepatitis C virus.
A Cochrane Review sought to determine whether interferon alfa-2a could be used as a treatment for individuals with neovascular age-related macular degeneration. They found no evidence of improved visual acuity with potential harm.
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- Reddy U, Krzystolik M (2006). "Antiangiogenic therapy with interferon alfa for neovascular age-related macular degeneration". Cochrane Database Syst Rev. 1: CD005138. doi:10.1002/14651858.CD005138.pub2. PMID 16437522.
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