SILICA PARTICLES FOR HYDROPHOBIC DRUG DELIVERY FROM SILICONE HYDROGELS

Abstract

<p>Topical administration of therapeutic eye drops is currently the most employed method of drug delivery for treatment of various ocular conditions. The poor drug bioavailability with this method of delivery requires frequent administration and results in low patient compliance. Drug eluting contact lenses have been proposed as a means to overcome the challenges associated with topical drug delivery due to the ability to increase drug residence time on the ocular surface and consequently increase corneal absorption. In this study, silica particles were prepared using microemulsion polymerization, and were embedded into a model silicone hydrogel consisting hydroxyethylmethacrylate (HEMA) monomer and a hydroxylated silicone monomer. Silica particles were specifically selected as the drug-containing particle system for loading into a silicone hydrogel to observe whether better control over the rate of drug release was possible by loading the hydrophobic drug in the silicone domain via the use of silica particles. Although similar dexamethasone release profiles were observed for hydrogels incorporated with suspensions prepared with or without silica shell precursors, transmission electron micrographs of these hydrogels indicate particle localization in silicone domains for suspensions prepared with silica precursors. This result is promising, and optimization of the drug-containing silica particle synthesis formulation may potentially allow for control over the drug release profile.</p>