Pegylated interferon alfa-2a, Pegasys, is a covalent conjugateof recombinant interferon alfa-2a (approximate molecularmass, 20 kDa) with a singly branched bis-monomethoxy PEGchain (approximate molecular mass, 40 kDa). The PEG moietyis linked at a single site to the interferon alfa moiety by astable amide bond to lysine. Peginterferon alfa-2a has anapproximate molecular mass of 60 kDa. Pegasys providessustained therapeutic serum levels for up to a full week(168 hours). The drug is approved for the treatment of adultswith chronic hepatitis C who have compensated liver diseaseand who have not been previously treated with interferon alfa.Efficacy has also been demonstrated in patients with compensatedcirrhosis.
