Delivery of ketotifen fumarate by commercial contact lens materials.

PURPOSE: To investigate the uptake and delivery of the anti-allergy drug ketotifen fumarate (KF) by commercially available contact lenses.
METHODS: A total of 14 different commercially available contact lenses were investigated, including five frequent-replacement silicone hydrogels, three conventional hydrogels, and six daily disposable lenses. Lenses were soaked in a 0.025% KF loading solution for 24 h, and the concentration of KF in solution over time was determined by ultraviolet absorbance at 297 nm. After the 24-h loading period, lenses were placed in fresh vials containing borate buffered saline, and the release of drug into solution at 34°C was monitored for 24 h.
RESULTS: All the lenses studied demonstrated significant uptake and release of KF into the borate buffered saline (p < 0.05 compared with initial time point). Lenses with charged surfaces [balafilcon A, etafilcon A, and etafilcon A (daily disposable)] demonstrated the greatest uptake and release of KF. Etafilcon A released 284.5 ± 29.8 μg/lens, whereas balafilcon A released 227.6 ± 14.7 μg/lens, which was substantially more (p < 0.05) than the lowest releasing lenses [nelfilcon A (40.4 ± 4.1 μg/lens) and comfilcon A (110.4 ± 8.9 μg/lens)]. The majority of lenses were able to match or exceed the total amount of KF commonly administered to the eye using twice-daily dosing of commercially available (0.025%) eye drop formulations. Most of the lenses surveyed reached a plateau concentration of KF relatively quickly, and no lens was able to release KF for longer than 4 h.
CONCLUSIONS: Commercially available lenses demonstrated the ability to release a clinically relevant amount of KF compared with conventional eye drops. The use of commercially available contact lenses as a KF delivery system in a daily wear scenario may be feasible.