Polyethylene glycol molecules

At present, two types of peginterferon-a are approved for the treatment of chronic hepatitis C peginterferon-a2a and peginterferon-a2b, which differ in size and form of the linked polyethylene glycol molecule (40 vs. 12kDa). Both pegin-terferons are injected subcutaneously once a week (see chapter by Chevaliez and Pawlotsky, this volume, for further details). 

Pegylated interferon is interferon that is attached to a polyethylene glycol molecule that increases the half-life of the drug, thus allowing once-weekly dosing versus thrice-weekly administration required for the unmodified formulation. Pegylated interferon is well tolerated and is superior in efficacy to unmodified interferon for the treatment of chronic hepatitis B.26... 

Figure 30 Temperature dependence of the permeability (P) of polyethylene glycol molecules for A-isopropylacrylamide (NIPAAm) grafted films. Polyethylene glycol with four kinds of masses (1 x 10, 1x10, 2x10, 7x10" ) are contained in the solution.

Pegfilgrastim was developed by adding a polyethylene glycol molecule to the A-terminus of filgrastim. In a phase III study in 301 patients with advanced breast cancer who underwent myelosuppressive chemotherapy a single injection of pegfilgrastim had similar efficacy and safety profile to repeated injections of filgrastim (94). 

In the later part of the article, the effect of cell surface modification is considered. Namely, polyethylene glycol molecules are anchored to the membrane surface to provide a steric barrier to fusion. The purpose is to provide a means to reduce unwanted fusion (i.e. stealthiness). Giant liposomes provide an excellent model with which to test this theory, because their external, internal and membrane conductivities and dielectric constants can be controlled precisely, and their surfaces can be easily modified. 

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