(571k) Controlled Release of a Phospholipid From Contact Lenses

Purpose: Contact lenses are known most commonly as a type of eye-wear designed to improve vision. However, since the majority of ocular medications are delivered to the eye in the form of solution, contact lenses could also be used to deliver medications to the eye. It is discovered that eye irritation has sometimes been associated with the lack of phospholipids in the tear film, leading to disruption of the tear film and subsequent perception of dryness. To deal with this problem, we explored the feasibility of loading a phospholipid into contact lenses for controlled release to the eye. Methods: Silicone hydrogel contact lenses were loaded with radio-labeled 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) from a solution of n-propanol. The loaded lenses were soaked at 35°C in either water or artificial tear solution (ATF). A lens was placed in a glass vial (with plastic snap cap) containing 3.00 mL of the fluid. Samples from the vial were collected at 0, 2, 4, 10, 24, 48 and 72 hrs by pipetting 0.1 mL from the vial into a scintillation vial containing 10 mL of scintillation fluid. Results: About 33 µg of DMPC was loaded into the lenses. An average of nearly 1 µg of DMPC was eluted into ATF within the first 10 hours. Elution was about 5 times faster in ATF than in water, which indicates that the elution appears to be controlled by the diffusivity of DMPC in the contact lens, and the properties of the elution solution. Other data also suggest diffusion-controlled elution from the lens in vitro. Conclusion: It is possible to load and elute DMPC in these particular silicone hydrogel contact lenses. Even though there are many aspects that require further study, such as the effect of lens chemistry, the effect of phospholipid chemistry, the effect of loading times and concentrations and so forth, this type of lens technology may have the potential to deliver phospholipids to help address eye dryness through lipid layer stabilization.