Pegylated interferons: Clinical applications in the management of hepatitis C infection

Abstract

Currently, there are two pegylated interferon (PEG-IFN) products available for the treatment of hepatitis C virus (HCV) infection [(pegylated interferon, PEGIFN alpha-2a (PEGASYS®), and pegylated interferon, PEG-IFN alpha-2b (PEGINTRON®)]. Pegylation is a process by which the interferon-alpha is bound to a polyethylene glycol moiety (Kozlowski & Harris, 2001). The PEG-IFN-alpha-2a product is bound to a single-branched bis-monomethoxy polyethylene glycol (PEG) chain (40,000 daltons) for a final molecular weight of 60,000 daltons or 60 kDa (kilodaltons). Four major positional isomers exist for this compound (Bailon et al., 2001) In contrast, PEG-IFN-alpha-2b is formed by attaching a single chain of PEG (12 kDa mono-methoxy PEG) to interferon-alpha-2b via an ester linkage. The PEG moiety is conjugated to the His34 amino acid residue, forming 12 positional isomers (Wang et al., 2000). The combined molecular weight of PEG-IFN-alpha-2b is smaller, about 31 kDa. The chemical structure and linkages of PEG-IFNs (alpha-2a and alpha-2b) are shown in Figure 1. © 2008 Springer Science+Business Media, LLC.