Peginterferon alfa-2a

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Peginterferon alfa-2a
Clinical data
Trade namesPegasys, others
AHFS/Drugs.comProfessional Drug Facts
License data
Routes of
Subcutaneous injection
ATC code
Legal status
Legal status
  • AU: S4 (Prescription only)
  • UK: POM (Prescription only)
  • US: ℞-only
  • EU: Rx-only
  • In general: ℞ (Prescription only)
CAS Number
  • none
Chemical and physical data
Molar mass19 241 g·mol−1 (unpegylated)
40 000 g/mol (pegylated)
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Pegylated interferon alfa-2a, sold under the brand name Pegasys among others, is medication used to treat hepatitis C and hepatitis B.[1] For hepatitis C it is typically used together with ribavirin and cure rates are between 24 and 92%.[1][2] For hepatitis B it may be used alone.[3] It is given by injection under the skin.[1]

Side effects are common.[4] They may include headache, feeling tired, depression, trouble sleeping, hair loss, nausea, pain at the site of injection, and fever.[1] Severe side effects may include psychosis, autoimmune disorders, blood clots, or infections.[1] Use with ribavirin is not recommended during pregnancy.[1] Pegylated interferon alfa-2a is in the alpha interferon family of medications.[1] It is pegylated to protect the molecule from breakdown.[4]

Pegylated interferon alfa-2a was approved for medical use in the United States in 2002.[1] It is on the World Health Organization's List of Essential Medicines.[5]

Medical uses[edit]

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.[6]

Host genetic factors[edit]

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,[7] 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 [8] demonstrated the same genetic variants are also associated with the natural clearance of the genotype 1 hepatitis C virus.

Other infections[edit]

Has also been used for Middle East respiratory syndrome and hepatitis E.[9]


It is pegylated with a branched 40 kg/mol PEG chain. The drug has been manufactured under the brand name Pegasys by Roche Pharmaceuticals. Due to changes in clinical practice - antiviral hepatitis drugs such as sofosbuvir have become much more important - Roche announced in 2020 that it would withdraw Pegasys from the market worldwide,[10] but subsequently sold the worldwide rights to pharma&, an Austrian / Swiss pharmaceutical company that ensures supply in the medium and long term almost worldwide (excluding China and Japan).[11][12][13]


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.[14]


  1. ^ a b c d e f g h "Peginterferon Alfa-2a (Professional Patient Advice) -". Archived from the original on 16 January 2017. Retrieved 12 January 2017.
  2. ^ "Pegasys 135 mcg and 180 mcg solution for injection in pre-filled pen - Summary of Product Characteristics (SPC) - (eMC)". Archived from the original on 13 January 2017. Retrieved 12 January 2017.
  3. ^ British national formulary : BNF 69 (69 ed.). British Medical Association. 2015. p. 639. ISBN 9780857111562.
  4. ^ a b "Peginterferon alfa-2a (Pegasys) - Treatment - Hepatitis C Online". Archived from the original on 23 December 2016. Retrieved 12 January 2017.
  5. ^ World Health Organization (2019). World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization. hdl:10665/325771. WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.
  6. ^ "Interferon alfa-2a Uses, Side Effects & Warnings". Retrieved 2020-01-10.
  7. ^ Ge D, Fellay J, Thompson AJ, et al. (2009). "Genetic variation in IL28B predicts hepatitis C treatment-induced viral clearance". Nature. 461 (7262): 399–401. Bibcode:2009Natur.461..399G. doi:10.1038/nature08309. PMID 19684573. S2CID 1707096.
  8. ^ Thomas DL, Thio CL, Martin MP, et al. (2009). "Genetic variation in IL28B and spontaneous clearance of hepatitis C virus". Nature. 461 (7265): 798–801. Bibcode:2009Natur.461..798T. doi:10.1038/nature08463. PMC 3172006. PMID 19759533.
  9. ^ "Peginterferon Alfa Monograph for Professionals -". Archived from the original on 16 January 2017. Retrieved 12 January 2017.
  10. ^ "Verzichtserklärung der Zulassung - Mittelfristig läuft Pegasys aus" (PDF). (German). Retrieved 4 December 2021.
  11. ^ "Pegasys (Peginterferon alfa-2a) langfristig weiterhin erhältlich" (PDF). (German). Retrieved 4 December 2021.
  12. ^ "pharma& portfolio". (German). Retrieved 4 December 2021.
  13. ^ "HALF-YEAR REPORT 2021, p.20" (PDF). Retrieved 4 December 2021.
  14. ^ Reddy U, Krzystolik M (2006). "Antiangiogenic therapy with interferon alfa for neovascular age-related macular degeneration". Cochrane Database Syst Rev. 1 (1): CD005138. doi:10.1002/14651858.CD005138.pub2. PMID 16437522.

External links[edit]