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View the video entitled About Pegylated Alpha Interferons Announcer: The information provided in this video is not intended as a substitute for professional medical advice. If you have any questions or concerns about your health, you should contact your health care provider. Segment 9: What is pegylation? Jacobson:I've already mentioned pegylated interferon as the latest improvement in therapy for hepatitis C. Let me explain briefly what pegylation is. Pegylation is a process that attaches a substance called polyethylene glycol--PEG for short--to a protein. PEG has long been used in everyday products, such as foods and cosmetics. When attached to an interferon molecule, PEG allows the interferon to stay in the body longer, which can extend its treatment effects. PEG molecules vary in size, and may be linear or branched. Let's look at the smaller of the two available molecules. This molecule stays at effective treatment levels within the body for about 10 to 12 days after injection. This allows for injections to be given just once per week, which is far less frequently than the 3-day-per-week regimen of standard interferon, and translates into significantly fewer injections over the course of treatment. In addition to allowing fewer injections, pegylation also provides more consistent levels of interferon within the body during that period. Dosing is also different with pegylated interferon alfa-2b. Although standard interferon was dosed in a single amount for all patients, studies found that response rates were highest in patients who weighed the least. By dosing the pegylated interferon alfa-2b according to a patient's weight, these variations have been avoided, producing more consistent sustained HCV response rates across all weight classes. So, by attaching a molecule of PEG to the protein, the duration of action and therefore the effectiveness of the interferon is improved.