Random Copolyester-Based Delivery Systems for Tear Protein Therapeutics in Ocular Surface Disorders

This study presents a polymeric drug delivery platform designed to address the limitations of conventional therapies for ocular surface and corneal disorders, such as dry eye disease (DED). Conventional treatments typically require frequent administration of eye drops, leading to poor bioavailability and patient adherence. We investigated the use of two random poly-(butylene succinate/diglycolate) copolymers, namely, P-(BS _x BDG _y ) at varying molar ratios (x, y) as vehicles for conjunctival drug delivery. Copolymers were synthesized and extensively characterized by their molecular structure, thermal and mechanical properties, and surface wettability. Prototype cylindrical devices (2 × 3 mm) were fabricated by microinjection molding. Lysozyme (Lys) and lactoferrin (Lf), two endogenous tear proteins with therapeutic relevance, were loaded into the polymer matrices, and their release profiles were evaluated. In vitro cytotoxicity assays confirmed the biocompatibility of the materials, supporting cell viability over 24 h. Protein release studies demonstrated a sustained release from the copolymeric matrices, with both proteins retaining structural integrity throughout the release period. These findings indicate that P-(BS₅₀BDG₅₀) and P-(BS₂₀BDG₈₀) based devices exhibit key features suitable for ocular surface drug delivery: structural adaptability, controlled release kinetics, and compatibility with biologically active macromolecules. These platforms may represent a promising tool for targeted and prolonged drug administration in ocular diseases requiring frequent and localized treatment.