Biodegradation study of PLGA as an injectable in situ depot-forming implant for controlled release of paclitaxel

In this study, poly(d,l-lactide-co-glycolide), PLGA, was developed as an in situ forming implants (ISFIs) to improve the therapeutic efficiency and to devoid the adverse effects of the Paclitaxel (PTX). ISFIs have received considerable attention as localized drug delivery systems. Different molecular weights of PLGA (502H, 503H, and 504H) were examined as an ISFI for PTX. In vitro experiments showed that PTX was released from PLGA over the course of 28 days. The profile of PTX release demonstrated a slow diffusion-controlled phase and afterward a more express degradation-controlled phase. The zero-order, first-order, Higuchi's, and Weibull models were applied to drug release data in order to elucidate release mechanisms and kinetics. Therefore, to confirm the results of PTX release, the process of the polymer degradation is evaluated for the direct determination of the monomers, glycolic acid, and lactic acid, via a novel HPLC method and measurement of pH.