Controlled release of betamethasone from vitamin E-loaded silicone-based soft contact lenses

Context: Betamethasone (BMZ) is an effective drug which is commonly used as an eye drop for the management of ophthalmic inflammations. Due to low ocular bioavailability, it is necessary to prepare and optimize an ocular drug delivery system for BMZ.Objective: In this study we tried to use vitamin E diffusion barrier for sustaining BMZ release.Materials and methods: Three commercial contact lenses were soaked in vitamin E solutions and swelling percentage, diameter, transmittance, binding capacity and release amount and time were evaluated in comparison with non-vitamin E-loaded pure lenses.Results: The results showed that vitamin E significantly decreased water content of contact lenses whereas, increased the lens diameter in both dry and wet states. It effectively blocked UV radiation which is harmful for the eye surface while had no significant effect on visible transmittance. BMZ loading capacity enhanced and release rate remarkably decreased after using vitamin E as a hydrophobic diffusion barrier.Discussion and conclusions: This study revealed that vitamin E can be applied as a hydrophobic diffusion barrier for controlling and sustaining BMZ release from silicone-based soft contact lenses into the lachrymal fluid. It can also protect eye tissues as an antioxidant by blocking the UV radiation.