Epigallocatechin Gallate-Loaded Gelatin-g-Poly(N-Isopropylacrylamide) as a New Ophthalmic Pharmaceutical Formulation for Topical Use in the Treatment of Dry Eye Syndrome

Given that biodegradable in situ gelling delivery systems may have potential applications in the design of ophthalmic pharmaceutical formulations, this study, for the first time, aims to develop gelatin-g-poly(N-isopropylacrylamide) (GN) carriers for topical epigallocatechin gallate (EGCG) administration in the treatment of dry eye disease (DED). By temperature triggered sol-gel phase transition of copolymers, EGCG-loaded GN was prepared at 32 °C and characterized by FTIR, NMR, and HPLC analyses. Results of WST-1 and live/dead assays showed that GN materials have good compatibility with corneal epithelial cells. Gradual biodegradation of delivery carriers allowed sustained release of EGCG without drug toxicity. Anti-inflammatory and antioxidant activity studies also indicated effective therapeutic drug levels at each time point within 3 days of release. In a rabbit dry eye model, corneal epithelial defects was ameliorated by treatment with single-dose administration of EGCG-containing GN. Furthermore, drug molecules released from carrier materials could prevent further tear evaporation and loss of mucin-secreting goblet cells in diseased animals. Our findings suggest that GN carrier is responsible for enhanced pharmacological efficacy of topically instilled EGCG, thereby demonstrating the benefits of using biodegradable in situ gelling delivery system to overcome the drawbacks of limited dry eye relief associated with eye drop dosage form.