Intron A; Pegasys
peginterferon alfa-2a; interferon alfa-2b
Standard DoseIn adults, 180 mcg injected subcutaneously once per week for 48 weeks. Pediatric dosing available for age 3 years and older; dosing is based on body surface area.
There are no food restrictions. 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.
AWP$ 1,225.79 / week
Potential Side Effects and Toxicity
Interferon has a high number of side effects associated with it: fatigue, headaches, nausea, chills, insomnia, anemia, pyrexia (fever), injection site reactions, loss of appetite, rash, myalgia (muscle pain), neutropenia, irritability, depression, 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, and thrombocytopenia. In the case of the psychiatric/emotional side effects, interferon has been associated with 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 illicit, 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.
Although interferon is no longer used in HCV treatment, it still has a potential role for treating HBV. That said, it is rarely used for HBV, 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 medications are easier to take (oral) 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.