In-situ tear fluid dissolving nanofibers enable prolonged viscosity-enhanced dual drug delivery to the eye

Liquid and semi-solid formulations are the most commonly used drug delivery systems for ophthalmic diseases. Upon application into the conjunctival sac, these systems introduce a variable and unphysiologically high liquid volume to the eye, resulting in overflow and extensive nasolacrimal drainage, accounting for dosing inaccuracy and short ocular residence time. In this study, we present nanofibrous electrospun scaffolds composed of biocompatible polymers, overcoming these challenges by immediate drug release. The fibers incorporate gentamicin and dexamethasone, intended for the treatment of bacterial conjunctivitis. Upon contact with the ocular surface, the nanofibers immediately dissolve in the tear fluid, quantitatively releasing the two actives, yielding over92% drug recovery, determined with fluorimetric and chromatographic quantifications methods. Simultaneously, the viscosity of the tear fluid increases, shown by complex viscometry measurements. A newly developed ex vivo microfluidic porcine cornea model was used to evaluated ocular residence time. In contrast to fluid eye drops, the contact time was significantly prolonged and 20 min after application, an increase in drug availability on the ocular surface of 342% was observed. Biocompatibility of the polymer system was demonstrated in an OECD approved in vitro cornea model. The antibacterial activity after processing was evaluated according to EUCAST guidelines, and storage stability of the system was confirmed over a 12-week period. This innovative drug delivery system poses a highly promising platform technology, overcoming challenges associated with conventional dosage forms for drug delivery to the anterior eye and thus significantly advancing therapeutic approaches.