Edaravone-loaded liposomes for retinal protection against oxidative stress-induced retinal damage

To optimize the retinal protective effects of submicron-sized liposomes (ssLips) containing edaravone for intravitreal administration, we investigated the effects of liposomal formulation on the pharmacological effects. Loading of edaravone into ssLips of around 50% entrapment efficiency was achieved by a calcium acetate gradient method. The in vitro radical-scavenging capacity of edaravone-loaded ssLip based on egg phosphatidylcholine (EPC-ssLip) and L-alpha-distearoyl phosphatidylcholine (DSPC-ssLip) was determined in RGC-5, a neuronal precursor cell line that can be differentiated to resemble retinal ganglion cells. Edaravone-loaded EPC-ssLip scavenged intracellular H2O2 radical more strongly than DSPC-ssLip, although there was only a small difference in cellular uptake of edaravone into RGC-5. An in vivo N-methyl-D-aspartate (NMDA)-induced disease model was used to investigate the retinal protective effects in mice. The edaravone-loaded EPC-ssLip significantly reduced NMDA-induced ganglion cell layer (GCL) cell death compared with free edaravone. Such protective effect was small in the case of DSPC-ssLip. These results may be related to the release profile of the edaravone from ssLips across the inner layers of the retina including GCL, indicating effective retinal protection of EPC-ssLip compared to that of DSPC-ssLip. EPC-ssLip is a promising carrier for edaravone in treating oxidative stress-induced retinal diseases. (C) 2011 Elsevier B.V. All rights reserved.