Advantages of PEG as Drug Carrier

Chemical Aspects Critical for the Pharmacokinetics of Drug Conjugates 

The chemical structure of the bond linking the drug to the polymer is of critical importance in the in-vivo behavior of conjugates, as it dictates the release rate from the polymer, or may even prevent it. Thus, it seems useful briefly to discuss the most important strategies of drug conjugation to PEG, although they can also be used for other polymers. 

Activated PEGs are available commercially from many sources, in particular Nektar Therapeutics, which now supplies the starting material for most such drug products that are FDA approved or in advanced clinical development. 

In these conjugates, a charge modification at one site may greatly affect the molecule s hydrophilicity. 

As an alternative means of obtaining labile prodrugs, advantage can be taken of specially designed, easy cleavable spacer arms between PEG and the drug. Examples of these strategies include  

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