Controlled-release interferon alpha 2b, a new member of the interferon family for the treatment of chronic hepatitis C

Introduction: Combination therapy with pegylated interferon alpha (Peg-interferon) and ribavirin is currently the cornerstone of antiviral therapy for chronic hepatitis C. Monotherapy with Peg-interferon still is important for the treatment of chronic hepatitis B. With the advent of new therapies, protease inhibitors for chronic hepatitis C and nucleotide inhibitors for chronic hepatitis B, there remains a need for interferon-based therapies. The side effects of Peg-interferon are a main disadvantage and represent a stumbling block for many patients to enter and continue therapy. Areas covered: In this review, the authors will discuss controlled-release interferon alpha 2b (CR2b) (Locteron (R), Biolex Therapeutics, Pittsboro, NC, USA), a new slow-release interferon alpha 2b preparation for the treatment of chronic viral hepatitis. Other alternative interferons will also be discussed. Expert opinion: CR2b is a slow-release microsphere preparation for the administration of plant-derived recombinant human interferon alpha 2b. Compared with Peg-interferon, treatment with CR2b shows less flu-like reactions and less depression, and is at least as effective as conventional Peg-interferon-based therapy in patients with chronic hepatitis C. CR2b has the added advantage of biweekly instead of once weekly administration. CR2b appears to cause more neutropenia than Peg-interferon alpha 2b. This may be due to higher trough serum levels of CR2b at the end of a dosing interval. The bone marrow effects of CR2b closely resemble those published for the registered Peg-interferon alpha 2a. CR2b appears to have at least comparable efficacy with fewer side effects than current registered Peg-interferons.