Drug release behavior of hydrophobic drug-loaded poly (lactide-co-glycolide) nanoparticles: Effects of glass transition temperature

Abstract

Poly(lactide-co-glycolide) has been widely used and studied because of its biocompatibility and biodegradability. Recently, effects of physicochemical properties of poly(lactide-co-glycolide) on drug release behavior of hydrophobic drug-loaded nanoparticles were studied, and it was suggested that the glass transition temperature (Tg) of copolymers greatly affected the drug release. In this study, we prepared rifampicin-loaded nanoparticles with 180-nm diameter using poly(DL-lactide-co-glycolide) (PLGA), poly(L-lactide-co-glycolide) (PLLGA), and their physical mixtures. We determined the crystalline states, glass transition temperatures, and in vitro release studies were carried out in phosphate-buffered saline at 37°C for 48h. The results of the drug release studies of PLGA nanoparticles with three different molecular weights indicated that the molecular weight had a greater influence on the drug release behavior than Tg in the molecular weight range of 10,000–20,000. Also, from the results of release studies of nanoparticles prepared using PLGA7510, PLLGA7510, and their physical mixtures, it was suggested that the influence of Tg on drug release behavior was greater than that of crystallinity when the molecular weights were same and the Tg of the substances were sufficiently higher than the ambient temperature.