Rapid loading and prolonged release of latanoprost from a silicone hydrogel contact lens

Abstract

Eye disorders are often treated with medicated eye-drops, a treatment system that suffers from patient non-compliance and drug delivery inefficiencies. Drug-eluting contact lenses could improve the rate of patient compliance and sustain the rate of delivery of the therapeutic. We report the technology to rapidly load hydrophobic drugs into silicone hydrogel contact lenses, loaded by 4 min or less of soaking the lens in a solution of the drug in n-propanol, followed by rapid deswelling in water. Using this loading system, the amount of hydrophobic drug placed into the lenses was controllable, with up to 450 μg per lens. Drug loading was proportional to the loading time and to the drug concentration in the solution. In vitro drug release from the lenses into artificial tear solution was proportional to total amount of drug loaded, appeared to be diffusion controlled for the first 3 days, and was completed by 4 days. Release into water was much slower. This method of rapid loading could be more feasible than conventional loading from aqueous solutions, particularly for hydrophobic drugs.