Development of puerarin-loaded poly(lactic acid) microspheres for sustained ocular delivery: In vitro/vivo evaluation

Diabetic retinopathy, an ocular complication of diabetes, is an important cause of blindness in adults. Puerarin is considered to have promising potential for clinical use in treating diabetic retinopathy. In this study, we designed a novel puerarin-loaded poly(lactic acid) sustained-release microspheres suitable for ocular administration, and we assessed its in vitro and in vivo properties. The preparation of puerarin-loaded microspheres was optimized by Box-Behnken response surface design. The encapsulation efficiency and drug loading of microspheres were 35.71% and 3.85%, respectively. The microspheres exhibited good dispersion and high safety, making it suitable for ocular drug delivery. In vitro release demonstrated that microspheres had a well-sustained release effectiveness, and its release behavior complied with the zero-order kinetic characteristics. The results of ocular tissue distribution revealed that the C_max and AUC_0-∞ of the microspheres group in the retina and choroid were considerably higher than those of the solution group and the intravenous injection group. This research revealed that intravitreal injection of microspheres can significantly prolong the half-life of puerarin in eye tissues and achieve sustained drug release. Therefore, intravitreal injection of microspheres has positive implications for the treatment of diabetic retinopathy.