Fabrication and Evaluation of PLGA Microsphere-Loaded Hydrogels as Potential Intraocular Lens for Sustained Release of Timolol Maleate

Eye drops suffer from challenges primarily associated with fast tear clearance, resulting in poor drug bioavailability. We developed a drug-eluting intraocular lens (IOL) that ensures a sustained release of timolol (maleate) as an antiglaucoma agent, for extended periods. Biodegradable poly(lactic-<i>co</i>-glycolic acid) (PLGA) microspheres encapsulated with timolol are first synthesized using the water-in-oil-in-water (w/o/w) double emulsion method. These drug-loaded microspheres are incorporated into poly(acrylamide-sodium acrylate) hydrogel (PAH) IOL cast from a 3D-printed mold, which is then monitored for sustained drug release for an extended period. Developed drug-loaded IOLs are transparent and flexible and demonstrate sustained release of timolol for over 7 weeks. This release duration is drastically higher than direct drug loading in the PAH film, i.e., the degradation control of drug release is much more efficient than drug transport by diffusion alone. Moreover, the incorporation of PLGA microspheres into the PAH film slows PLGA degradation, resulting in a 3-fold increase in release duration when compared to that of standalone microspheres. The resulting system ensures a long-term, patient-friendly approach to glaucoma treatment.