Pegasys
peginterferon alfa-2a (PEG-IFN)
Standard Dose
For adults: 180 mcg injected subcutaneously once per week for 48 weeks. Dose should be given in the abdomen or thigh. Injection sites should be rotated. There are no food restrictions.Dose should be given on the same day and at approximately the same time each week. Take your missed dose as soon as possible on the same day or the next day and then continue your regular dosing schedule. If multiple days are missed, check with your medical provider about what to do. Never double dose or take doses too close together.
Dose adjustments are needed for individuals with kidney disease (see chart below) and those with significant side effects. Pegasys is also available for pediatric patients aged 3 years and older; dosing is individualized based on body surface area.
Manufacturer
GenentechAWP
Pegasys180 mcg/mL solution: $1,336 / week
180 mcg/0.5 mL prefilled syringe: $1,336 / week
Potential Side Effects and Toxicity
Interferon has many potential and possibly serious side effects including: fatigue, headaches, nausea, chills, insomnia, anemia, pyrexia (fever), loss of appetite, rash, myalgia (muscle pain), neutropenia, alopecia (hair loss), dyspnea (shortness of breath), arthralgia (joint pain), pruritus (itching), flu-like feelings, dizziness, diarrhea, cough, weight loss, vomiting, unspecified pain, dry skin, anxiety, abdominal pain, leukopenia (low white blood cell count) and thrombocytopenia (low platelet count). Psychiatric/emotional side effects are possible. Interferon has been associated with irritability, depression, anxiety and, in rare cases, suicidal thoughts. If you have a history of any of these conditions, talk to your provider before starting HBV treatment with interferon. It does not mean you can’t take interferon (or another HBV treatment), but you want to watch for signs of worsening depression and be able to take preventative actions ahead of time. As an injectable, injection site reactions (redness, swelling, and/or itching) and inflammation are common. If you have autoimmune hepatitis or are allergic to any of the ingredients in interferon, you should not take it.
Potential Drug Interactions
There are few drug interactions with interferon. However, be sure to tell your medical provider or pharmacist about all the medications, supplements, and herbal products you take, whether prescribed, over-the-counter, or recreational, before starting this drug, and inform them of any changes to your medications as they happen. Caution is advised when taken with warfarin, phenytoin, or methadone. Methadone levels may increase due to interferon, so methadone levels and signs and symptoms of a stronger narcotic effect should be monitored. Use caution when taken in combination with other medications with similar side effects, such as neutropenia, as this could cause worsening symptoms.
More Information
Although interferon is no longer used in HCV treatment, it still has a potential role for treating HBV, and is currently the only effective treatment for individuals co-infected with Hepatitis D (HDV). That said, it is rarely used for HBV mono-infection, and the World Health Organization does not include it in their HBV guidelines. Interferon will not cure HBV—currently, no HBV medication will cure you—but it can decrease your risk of long-term complications such as cirrhosis or liver cancer. It has some clinical advantages over the oral antivirals, as it’s a finite therapy and it doesn’t lead to HBV resistance, but it’s a difficult medication to take (injection) and tolerate. Other oral medications are easier to take with fewer side effects. Interferon is less safe for people who have any level of cirrhosis and should never be used by someone with decompensated cirrhosis. The AASLD Guidelines for the Treatment of Hepatitis B do include pegylated interferon alfa, along with Baraclude (entecavir or ETV), Viread (tenofovir disoproxil fumarate or TDF) and Vemlidy (tenofovir alafenamide or TAF) as first-line agents in the treatment of HBV. If you need HBV treatment, talk to your medical provider about which option is best for you.