Poly(dl-lactide-co-glycolide) 50:50-hydrophilic polymer blends: Hydrolysis, bioadhesion and drug release characterization

Poly(d,l-lactide-co-glycolide) (PLGA) is a biocompatible, biodegradable copolymer utilized for its degradation properties in drug delivery and as a tissue scaffold. PLGAs show low polarity surface characteristics, which will not promote bioadhesion. PLGA polyblends with hydrophilic polymers were used to alter PLGAs polarity to enhance its bioadhesion and utility for tissue scaffolds. The effect of polyblends on PLGA hydrolysis and drug release was also explored.;Hydrophilic polymeric additives were expected to increase PLGA hydrolysis by increasing water-uptake. PLGA blends with polyethylene oxide (PEO), hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC) and sodium chloride (NaCl) were hot-melt extruded and their hydrolysis behavior studied in phosphate buffered saline. Hydrolysis kinetics of PLGA blends was characterized by weight loss, pH and gel permeation chromatography (GPC) measurements. Pure PLGA showed its characteristic bulk hydrolysis. Water-uptake increased with blends but retardation of PLGA hydrolysis at > 10 % hydrophilic compositions was observed. GPC showed that polyblends decreased PLGA hydrolysis rates by 3- to 5-fold with increasing hydrophilic composition compared to pure PLGA. The increased induction times before dramatic mass loss coincided with the rapid water-uptake and rapid pH decline. All hydrophilic polymers at higher compositions produced porous matrices by polymer dissolution except HPC which induced swelling with little mass loss. These results suggested that PLGA hydrolysis retardation was due to loss of acidic catalysts (hydrolysis products) through the porous matrix. This behavior was unexpected but indicated the important role of porosity in PLGA hydrolysis.;Polyblend bioadhesion was investigated for mucus and cell adhesion. Adhesion was dependent on polymer blend properties and composition. PLGA-HPC blends showed the maximum work of mucoadhesion at 50 % loading. Fibroblast cells showed significant attachment and growth on PLGA-HPC-LMW porous scaffolds compared to other PLGA blends.;Modulation of ibuprofen drug release from PLGA-hydrophilic polyblends was investigated. Most PLGA polyblends showed release profiles that followed polymer erosion whereas HPC showed a release profile that was diffusion-controlled through a swollen porous matrix.;It was concluded that PLGA blends with hydrophilic materials can be used to alter PLGA hydrolysis, enhance bioadhesive properties and modulate drug release.