Ophthalmic drug delivery through contact lenses

PURPOSE. Currently available ophthalmic drug delivery systems are inefficient and may lead to side effects. To increase efficiency and reduce side effects, the authors propose disposable particle-laden soft contact lenses for ophthalmic drug delivery. METHODS. The essential idea is to encapsulate the ophthalmic drug formulations in nanoparticles and to disperse these drug-laden particles in the lens material, such as poly-2-hydroxyethyl methacrylate (p-HEMA) hydrogels. The drug-laden p-HEMA hydrogels were synthesized by free radical solution polymerization of the monomers in presence of nanoparticles. The particle-laden hydrogels were characterized by light-transmission and electron microscopy studies. Release profiles of lidocaine, a model hydrophobic drug, were measured by UV-Vis spectrophotometry. RESULTS. Microemulsions of hexadecane in water stabilized with a silica shell around the particles produced transparent hydrogels. Contact lenses made with particle-laden hydrogels released therapeutic levels of drug for a few days. CONCLUSIONS. Particle-laden hydrogels are promising candidates for ophthalmic drug delivery. They are transparent and can release drugs for extended periods. The drug delivery rates can be controlled by varying the loading of nanoparticles in the gel.