With the discovery of insulin for the treatment of diabetes, the protein and peptide drug delivery systems has gained much attention .Of all the routes of administration, the parenteral route is the most common .But because of the ease of administration and high patient compliance these days oral route is preferred. As the oral route also has its own limitations ,the delivery of proteins and peptides by this route has been a challenge and a goal for many decades .Hence ,in order to overcome the problems in oral drug delivery such as high acidity of stomach ,the enzymatic degradation of proteins ,and in order to attain maximum stability and solubility several formulation excipients are preferred in the formulation .And one such excipient employed is polyethylene glycol and the covalent modification of the protein and peptide drugs with polyethylene glycol is known as PEGYLATION .PEGylation is now considered as one of the most successful techniques to prolong the residence time of protein drugs in the blood stream. This mechanism increases the half life by covalent modification of the therapeutic proteins with PEG can result in increased serum half life due to decreased renal clearance .It enhances the biophysical properties of the drug, enhances the solubility and stability of the product.
This strategy is useful to obtain derivatives or conjugates with predictable pharmacokinetic and distributional behaviour. Along with, the polyethylene glycol has many ideal properties such as high persistence in blood, low accumulation in the reticulo- endothelial cells, and excellent solubility in aqueous solutions. In my presentation, I will discuss in detail about the chemistry of PEG conjugates with protein and peptide delivery systems, their pharmacokinetic and bio distribution properties and their clinical evaluation.