Available in the form of an injection, Pegasys is used to treat hepatitis B and hepatitis C. The injection is given just under the skin (subcutaneously) once a week for 24 to 48 weeks. This prescription drug works by activating the body's own response to viruses. Side effects may include fatigue, headaches, and muscle aches.
What Is Pegasys?Pegasys® (peginterferon alfa-2a) is a prescription medication approved to treat hepatitis C and hepatitis B. When used to treat hepatitis C, it works best when combined with ribavirin, although it can also be used alone if necessary. For hepatitis C virus genotype 1 infections, it works even better when combined with both ribavirin and a hepatitis C protease inhibitor like Incivek® or Victrelis®, although such a combination is not appropriate for all individuals.
How Does Pegasys Work?Pegasys is a manufactured version of interferon and is almost identical to a naturally occurring human interferon. Interferons are naturally occurring proteins or glycoproteins (proteins attached to carbohydrates). In humans, interferons are produced by cells in response to certain situations, such as viral infections, and often play a key role in the immune system.
When given as medications, interferons do not last very long in the body. To get around this problem, Pegasys was made by attaching each interferon to a molecule of polyethylene glycol. This makes the medication last much longer, allowing for once-a-week dosing. Because Pegasys is a protein, it would be broken down and destroyed by the digestive system if taken by mouth. For this reason, Pegasys must be injected to bypass the digestive tract.
Pegasys works to fight hepatitis B and C by activating the body's own response to viruses.