Flexible coils with a drug‐releasing hydrophilic coating: A new platform for controlled delivery of drugs to the eye?

Delivery of drugs to the front‐side of the eye is routinely done through eye drops. It is known that approximately 80% of each eye‐drop is lost, as a result of rapid clearance of the tear fluid via the naso‐lacrymal canal. Consequently, repeated administration through several droplets is usually necessary to achieve a desired effect, e.g., mydriasis (widening of the pupil) prior to corneal surgery. Studies with a new ocular drug delivery device are reported. The new device is believed to provide a basis for more convenient and efficient method for ocular drug delivery. The device is a metallic coil with a hydrophilic, drug‐containing polymeric coating. The coil is placed in the conjunctival fornix (under the lower eye‐lid), and the drug is released slowly, by diffusion into the tear fluid. The capacity of the device could be increased by using the lumen of the coils as a depot for the drug to be released. Preliminary experiments with the new device are reported. These experiments were performed largely in vitro, but partly also in vivo. The latter experiments comprised release of the fluorescent dye, and delivery of atropine (a potent mydriatic agent), in the eyes of several healthy volunteers. The first results obtained with the new device indicate its potential utility. It is discussed that much more research and development work is required, e.g., to define the optimal design of the coil in order to minimise the risk for irritation. Furthermore, the parameters that define the kinetics of the intraocular drug release must be defined and optimised with respect to the exact application.