Phase inversion dynamics of PLGA solutions related to drug delivery

Dark ground optical microscopy, electron microscopy, and high performance liquid chromatography (HPLC) have been used to quantify the effects of formulation changes on the phase inversion dynamics and in vitro drug release properties of a PLGA-based drug delivery system. Gel growth rates and water influx rates are determined from plots of the square of the respective front motion with time. Results show that additives that accelerate the solution gelation rate at constant morphology result in high initial release rates. Conversely, additives that slow the rate of gelation dramatically reduce the initial drug release rate and lead to a more dense sponge-like morphology. Moreover, the phase inversion dynamics and morphology are the same regardless of whether the solutions are quenched with water, a PBS buffer solution or horse serum. (C) 1999 Elsevier Science B.V. All rights reserved.