(446f) Silicone Hydrogel Contact Lenses Loaded with Unsaturated Fatty Acids for Extended Release of Cationic Drugs

Contact lenses are potential candidates for the delivery of ophthalmic drugs with high bioavailability and reduced risks of side effects. Studies have shown that the residence time of ocular drugs in the tear film can be increased from 2 minutes for eye drops, to 30 minutes for drug-eluting contact lenses. However, unmodified contact lenses tend to release drugs very quickly; most of the drug loaded is released in less than a few hours. We propose the use of unsaturated fatty acids in silicone hydrogel contact lenses to extend the drug release duration of cationic ophthalmic drugs. Silicone hydrogel commercial contact lenses (ACUVUE TruEye and ACUVUE Oasys) are soaked in fatty acid-ethanol solutions for fatty acid uptake. Lenses are subsequently submerged in a solution of drug in phosphate buffer saline (PBS) for drug uptake. In vitro drug release experiments are performed by immersing each drug-loaded lens in PBS media at 7.4 pH. Drug concentration as a function of time is monitored by using Ultraviolet-Visible Spectrometry at the wavelength of maximum absorbance of each tested drug. The results obtained show that oleic acid-loaded contact lenses significantly extend the release time of cationic drugs from less than 24 hours, to more than 1 month. The drug release of cationic drugs is dependent on the weight percent of fatty acid in the contact lenses, and in the number of double bonds in the alkyl chain of the fatty acid that is loaded in the lens matrix. The addition of oleic acid in contact lenses has a negligible effect on the optical transparency of the lenses, but has a moderate effect on the water content of the lenses depending on the amount loaded. Due to the low ocular toxicity associated with unsaturated fatty acids, contact lenses loaded with these can be promising materials to be used in ocular drug delivery. Future studies on lens characterization and cell viability need to further assess the potential of these biomaterials.