Issue Date: Vol. 3 No. 5 July/August 2003, Posted On: 3/28/2008
PLGA-PEG Block Copolymers for Drug Formulations
By: Kang Moo Huh, PhD; Yong Woo Cho, PhD; and Kinam Park, PhD
Over the past few decades, biodegradable
polyesters, such as poly(lactic acid) (PLA),
poly(glycolic acid) (PGA), and poly(lactic-co-
glycolic acid) (PLGA), have been extensively studied for a wide variety of pharmaceutical and biomedical applications.
The biodegradable polyester family has been regarded as one of the few synthetic biodegradable polymers with
controllable biodegradability, excellent biocompatibility, and high safety. The need for a variety of drug formulations for
different drugs and delivery pathways resulted in development of various types of block copolymers (eg, diblock, triblock,
multiblock, and star-shaped block) consisting of the biodegradable polyesters and poly(ethylene glycol) (PEG). Extensive
studies throughout the world have produced encouraging results demonstrating many desirable, unique properties of
PLGA-PEG block copolymers. Despite successes in preclinical applications and ever-increasing uses in diverse
research activities, PLGA-PEG block copolymers are currently not available commercially. Recognizing that demands for
PLGA-PEG block copolymers in pharmaceutical and biomedical applications will continue to grow, Akina, Inc.,
(www.akinainc.com/polycelle) has started production of PLGA-PEG block copolymers for those who want to use the
block copolymers but are not willing to synthesize themselves. This article describes synthesis of PLGA-PEG block
copolymers and their applications as drug delivery vehicles, such as micro/nano-particles, micelles, hydrogels, and
injectable delivery systems.
Recently, biodegradable polymers, especially poly(lactic acid) (PLA), poly(glycolic acid) (PGA), and poly(lactic-co-
glycolic acid) (PLGA), have been used significantly in pharmaceutical and biomedical applications. Poly(lactic acid), poly
(glycolic acid), and poly(lactic-co-glycolic acid) have also been called polylactide, polyglycolide, and poly(lactide-co-
glycolide), respectively, according to the nomenclature system based on the source of the polymer. Although these
names were used in many references in the past, a recent trend is to follow the nomenclature system of the International
Union of Pure and Applied Chemistry (IUPAC) that is based on the repeating unit structure. PLA, PGA, and PLGA can
be degraded into non-toxic substances and removed from the human body. Accordingly, they have taken center stages
in a variety of research efforts.
The biodegradable polyesters are all strongly hydrophobic, and this has caused some limitations in practical drug
formulations. To add hydrophilic and other physico-chemical properties, poly(ethylene glycol) (PEG) has been
incorporated into the biodegradable polyesters. PEG is a non-toxic, water-soluble polymer with proven biocompatibility.
Block copolymers consisting of a hydrophobic polyester segment and a hydrophilic PEG segment have attracted large