Synthesis of amorphous polylactide and poly (lactide-co-glycolide) containing high L-form enantiomer for use in controlled release drug delivery

Abstract

In this work, the effect of L-lactide (LL) copolymerization on the properties of poly(D,L-lactide) (PDLL) and poly(D,L-lactide-co-glycolide) (PDLLG) copolymers and its drug release behaviors were determined and discussed. The copolymers were synthesized by ring-opening polymerization of DLL, LL, and G monomer mixtures. The PDLL with DLL/LL ratios of 100/0-50/50 by mole and the PDLLG with DLL/LL/G ratios of 75/0/25-37.5/37.5/25 by mole were investigated. All the copolymers were completely amorphous. The drug-loaded copolymer microparticles with a spherical shape and smooth surface were prepared by the oil-in-water emulsion solvent evaporation method. Indomethacin was used as a poorly-water soluble model drug. The copolymerization of the LL monomer did not change the in vitro drug release profiles of the PDLL and the PDLLG microparticles significantly. It is suggested that these amorphous PDLL and PDLLG copolymers that contain higher L enantiomer amounts have the potential to be developed further as a lower-cost PDLL and PDLLG, respectively, for use as controlled release drug delivery systems.