In vitro and in vivo degradation of poly(D,L lactide/glycolide) type microspheres made by solvent evaporation method.

Microspheres of different poly(alpha-hydroxy acids) were prepared by solvent evaporation to study the effects of gamma-sterilization on stability and to establish the degradation process in vitro and in vivo. gamma-Irradiation dramatically decreases polymer molecular weight and this degradation continues on storage. gamma-Irradiation modifies the controlled release pattern of cisplatin-loaded microspheres. After embolization of rat livers by microspheres, a histological study of the inflammatory response was made, along with gel permeation chromatography analysis of degrading polymers. The degradation rate of the polymers increased with the glycolic unit content in the lactic chains. Scanning electron microscopy of microsphere degradation in vitro correlated with the former observations.