Release rate determination from in situ gel forming PLGA implant: a novel ‘shape-controlled basket in tube’ method

Abstract

Abstract Objectives This study aimed to examine the impact of syringe-needle assembly differences in making implants of different shapes as well as its influence on the release kinetics and investigate the release kinetics of the in situ forming implant under various release arrangements. Methods PLGA in situ forming implant was prepared in different shape and then subjected to in vitro release testing. Mathematical modelling was used to investigate drug release mechanisms. Key findings The in situ forming implant was investigated for the first time how implant shapes can affect release results. It was demonstrated that implant shape differences could lead to significant variation in the release data. Here, we addressed this issue by developing a shape-controlled method to provide a consistent surface to volume ratio and, therefore, a reliable release result. Injectability in the in vitro release was discussed for the first time. Comparisons between various release methods were also evaluated. The release arrangement was found to be of great importance in release kinetics. Conclusions The developed ‘shape-controlled basket in tube’ method can provide the most reproducible release profiles by minimizing implant adhesion to the release vessels or movement without sacrificing full contact between the release medium and the implant surface.