(475h) Sustained Ophthalmic Delivery of Timolol from Molecular Imprinted Contact Lenses

Molecular imprinting is a method for tailor-made preparation of polymers possessing recognition sites complementary to a guest molecule. The technique involves the formation of complexes between guest molecules and functional monomers, followed by polymerization in the presence of cross-linker and backbone monomers. After removal of the guest molecules, the active sites for the guest should be fabricated in the polymer network. Hydrogels made by molecular imprinting can absorb specific molecules from and release them into a surrounding solution. Taking advantage of the comfortable feeling and biocompatibility, weakly cross-linked hygrogel is a suitable material for soft contact lens. Hydrogel made by molecular imprinting that can capture the guest drugs effectively and release them in a controlled fashion could apply for therapeutic contact lens materials as an ophthalmic drug delivery system. Based on this idea, this study investigates the possibility that soft contact lenses made by molecular imprinting can store more the guest drug, timolol, than the corresponding non-imprinted control contact lenses. Furthermore, we investigated the influence of the guest/functional monomer, timolol/methacrylic acid (MAA), proportion on the achievement of molecularly imprinted contact lenses with a high enough affinity for the drug to sustain drug release. The imprinted lenses showed a higher affinity for timolol and slower release rate than the non-imprinted lenses. The release rate decreased by increasing the MAA/timolol ratio in the lens recipe. The results obtained clearly indicated that the timolol release rate is critically affected by the condition under which the contact lenses were synthesized.