Effects of ionizing radiation sterilization on microparticulate drug delivery systems based on poly-alfa-hydroxyacids: an overview.

Ionizing radiation treatment is particularly advantageous as a sterilization technique for polymeric drug delivery systems. In recent years
several authors have investigated this topic with interesting and sometimes controversial results. This overview was aimed at gathering and critically
discussing the studies performed on the effect of ionizing radiation sterilization on microparticulate drug delivery systems made of poly-α-
hydroxyacids. The results reported in the literature showed that ionizing radiation always led to a decrease in poly-α-hydroxyacids molecular
weight. This effect was strictly related to irradiation dose, irradiation conditions, and depended on the starting polymer molecular weight. The
presence of a drug and/or an additive inside the polymeric micromatrix could affect polymer behavior upon irradiation and consequently drug
release behavior. Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) proved to be useful techniques to
elucidate the radiolytic mechanisms and the drug /polymer interaction upon irradiation.