CHANGE IN DRUG RELEASE MECHANISM FROM PLGA MICROPSHERES AT ELEVATEDTEMPERATURE

摘要

Drug release from three different PLGA microsphereformulations was evaluated under “real-time” andaccelerated release testing conditions such as elevatedtemperature and flow rate. Formulation 1 composed oflow Mw PLGA exhibited diffusion controlled kineticsunder both “real-time” and accelerated conditions.Whereas, Formulations 2 & 3 (composed of medium andhigh Mw PLGA) followed erosion controlled kinetics at37°C and diffusion controlled kinetics at elevatedtemperature, with time to complete drug release beingreduced from months to days. All three formulationsexhibited pore closing at elevated temperature withconsequent reduction in the burst release phase. Thefollowing microspheres characteristics were evaluated:drug release rate, morphology, Mw change, the glasstransition temperature (Tg) and crystallinity.