Limitations on today's technology
QuiaPEG's advantages


Polyethylene glycol (PEG) consists of long chains of ethylene glycol, which can be synthesized as linear or branched and to any length, depending on the intended properties. The PEG polymer is simultaneously hydrophilic, lipophilic, and water soluble. Typically, PEG is linked to a protein or peptide through reactive molecular groups on amino acid side chains - most often lysine.

PEGylation is a process in which one or more units of chemically activated PEG are coupled to a biomolecule, usually a protein, peptide, small molecule or oligonucleotide, creating a new molecular entity, which possesses physicochemical and physiological characteristics that are distinct from the original molecules. PEGylation has a number of potential advantages. It increases the hydrodynamic radius of the protein, which results in slower hepatic clearance and/or renal glomerular filtration and protects the protein from proteolytic degradation. The resulting net effect is an increased in vivo half-life – which means less frequent dosing to patients and thus reduced requirement for the often very expensive active pharmaceutical ingredient (see figure 1).

PEGylation usually increases the solubility which is also an important pharmaceutical aspect. Furthermore, as a rule, PEGylation reduces immunogenicity, thus potentially mitigating the risk of development of antibodies against the therapeutic protein which can lead to loss of efficacy or sometimes even allergic reactions. 

Since each protein and peptide has unique characteristics it is necessary to develop a number of PEGylated variants and assess and compare their biological effects before selecting a candidate drug with optimal properties.


Figure 1

  • Prevent spikes in plasma concentration -> reduced toxicity
  • Prevent periods of low plasma concentration -> increased efficacy
QuiaPEG Pharmaceuticals Holding AB

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