Drug-loaded ophthalmic lenses are presently considered promising drug delivery vehicles for the most prevalent disorders in the anterior and posterior segment of the eye, to avoid the low bioavailability and the limited patient compliance associated with eye drops. For example, intraocular lenses (IOLs) can be loaded with antibiotics and anti-inflammatories to prevent endophthalmitis. Moreover, soft contact lenses (SCLs) can also be used to deliver, in a controlled way, drugs for the treatment of keratitis and conjunctivitis. This work aims to study the effects of different loading conditions in the drug release from drug-loaded IOLs and SCLs.
Two ophthalmic materials, CI26Y (hydrophilic acrylate) for IOLs and DEFINITIVE50 (silicone hydrogel) for SCLs, from Contamac, were loaded by soaking in ketorolac, moxifloxacin and diclofenac solutions. Different loading conditions were used: temperatures of 4°C and 60°C, and soaking periods of 4 days, 1 and 2 weeks, 1, 2 and 3 months. Drug release experiments were performed and the concentration of the drug released was determined by UV-VIS spectroscopy. Swelling experiments were performed at 3 different temperatures (4°C, 25°C and 60°C).
For DEFINITIVE50, optimization of the drug loading conditions led to the increase in the amount of drug loaded but didn’t improve the release kinetics. For CI26Y, the increase in the loading temperature had different effects on the release profiles of all drugs. For moxifloxacin, an excellent release profile was obtained when loading the drug at 60°C, independently of the soaking time. In contrast, for ketorolac and diclofenac, controlled release was achieved when loading at 60°C for long periods (>1 month). The swelling experiments revealed that the swelling capacity increased at lower temperatures only for DEFINITIVE50, demonstrating that swelling didn’t determine the loading of CI26Y.
We conclude that through optimized drug loading conditions it’s possible to obtain controlled release of ophthalmic drugs from IOL materials.