Pegylated Interferon a-2a (40 kD)

Pegylation is a technique that a biological active protein molecule is covalently bound to polyethylene Glycol polymers (PEG). The pegylated protein obtained usually retains its biological action. Moreover, the water cloud surrounded this pegylated molecule decreases its renal clearance, proteolytic degradation as well as its immunogenicity. These therapeutic benefits lead to an improve in the bioavailability as well as a longer biological half-life of the pegylated compound. However, the achievement of these advantage depends on the molecular size of PEG used. When a high molecular weight branched molecule of PEG was linked to interferon-α-2a, a 40KD-pegylated interferon (PEG-IFN) molecule was obtained. The large molecule of this 40KD PEG-IFN possesses a very long biological half-life with small volume of distribution. These properties allow 40KD PEG-IFN to be administered in a weekly regimen and as fixed dose. Only one injection per week is enough to maintain the therapeutic blood concentration. Thus, better compliance and better quality of patient's life could be expected. Clinical studies on the effectiveness of 40KD PEG-IFN in the treatment of viral hepatitis revealed a better therapeutic achievement when compared to standard IFN either when 40KD PEG-IFN is used as monotherapy or in a combination regimen. The suggested dose of 40KD PEG-IFN is 180 μg once a week.