Therapeutic Effect of Cilostazol Ophthalmic Nanodispersions on Retinal Dysfunction in Streptozotocin-Induced Diabetic Rats

We previously prepared ophthalmic formulations containing cilostazol (CLZ) nanoparticles by bead mill methods (CLZ(nano)), and found that instillation of CLZ(nano) into rat eyes supplies CLZ into the retina. In this study, we investigated changes in the electroretinograms (ERG) of streptozotocin-induced diabetic rats (STZ rats), a model of diabetes mellitus. In addition, we demonstrated that dispersions containing CLZ nanoparticles attenuate changes in the ERG of STZ rats. The instillation of CLZ(nano) had no effect on body weight or plasma glucose and insulin levels. Furthermore, no corneal toxicity was observed in the in vivo study using STZ rats. The a-wave and b-wave levels in addition to oscillatory potentials (OP) amplitude decreased in STZ rats two weeks after the injection of streptozotocin, with the instillation of CLZ(nano) attenuating these decreases. In addition, the level of vascular endothelial growth factor (VEGF) in the retinas of STZ rats was 9.26-fold higher than in in normal rats, with this increase also prevented by the instillation of CLZ(nano) Thus, we have found that a-wave and b-wave levels in addition to OP amplitude are decreased in rats following the injection of excessive streptozotocin. Furthermore, the retinal disorders associated with diabetes mellitus are attenuated by the instillation of CLZ(nano). These findings provide significant information that can be used to design further studies aimed at developing anti-diabetic retinopathy drugs.