title: Designing PEGylated therapeutic molecules: advantages in ADMET properties.
abstract: BACKGROUND
  PEGylation, association of poly(ethylene glycol) (PEG) to drug molecules or drug-bearing particles, is one of the most promising techniques on the way to improve the pharmacokinetic features of a drug which, in turn, leads to pharmacodynamic improvements.
  
  
  OBJECTIVE
  The aim of this review is to describe PEGylation as a procedure for alteration of drug molecular structure with the main emphasis on its pharmacokinetic consequences.
  
  
  METHODS
  After a brief but concise overview of the history and chemistry of PEGylation, the boundary of this literature survey is confined to the findings and reports on the impact of PEGylation on biodistribution and bioelimination of therapeutic molecules.
  
  
  CONCLUSIONS
  It is concluded, based on the whole body of the data in literature, that the main results of PEGylation on pharmacokinetic properties of the drug include prolongation of lifespan in circulation, alterations in drug elimination pathway(s) and changes in drug biodistribution profile, among others, which all are derived from the structural changes that occur in the drug molecule, mainly reversible attachment of a large polymeric moiety to parent drug.
authors.affiliation: Department of Pharmaceutics, Faculty of Pharmacy, Shiraz University of Medical Sciences, PO Box 71345-1583, Shiraz, Iran.
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Hamidi
authors.forename: Pedram
authors.initials: P
authors.lastname: Rafiei
authors.forename: Amir
authors.initials: A
authors.lastname: Azadi