Abstract
Purpose :
Contact lenses containing ophthalmic drugs can help drug molecules to have a longer residence time in the post-lens tear film of the eye and to have a more direct path than eye drops. However, a major limitation of contact lenses is that most of the drug absorbed is released within the first few hours of therapeutic period. We proposed the inclusion of a cationic surfactant in microemulsion-loaded soft contact lenses for the controlled release of poorly water-soluble anionic drugs.
Methods :
Oil-in-water cationic microemulsions were formulated and added to a monomer mixture for the preparation of soft-contact lenses using thermal free-radical polymerization. Ophthalmic drugs were added either in the oil phase of the microemulsion or absorbed by soaking the lenses in a drug-aqueous solution. The concentration of the drugs being released as a function of time was monitored using Ultraviolet-Visible Spectroscopy. Microemulsions were characterized using Dynamic Light Scattering and Transmission Electron Microscopy, while optical transparency and swelling studies were performed to evaluate the fabricated contact lenses.
Results :
Unlike neutral microemulsions, cationic microemulsions have the ability to increase the retention of poorly water-soluble anionic drugs in the microemulsion phase of the contact lenses, thus extending the drug delivery from a few hours to several days. Furthermore, the inclusion of a cationic surfactant improves the stability of the microemulsions, increases the optical transparency of the contact lenses, and has the potential of enhancing the precorneal residence time of drug molecules through the electrostatic interactions.
Conclusions :
The development of positively charged microemulsions in contact lenses represents an alternative to the ocular delivery of pharmaceuticals to the eye with higher efficacy and bioavailability than conventional eye drops. Animal studies can be used to confirm the efficiency of the approach and to demonstrate the possibility of a novel biomaterial for the controlled ophthalmic delivery of drugs.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.