Ocular drug delivery from molecularly-imprinted contact lenses

Soft contact lenses (SCLs) are particularly attractive as drug delivery devices capable of overcoming certain limitations of conventional ophthalmic formulations. Although the Main use of commercially-available SCLs is for correcting ametropia problems, they may also uptake certain drugs and release them into the postlens lachrymal fluid, minimizing the clearance and the sorption through the conjunctiva. Novel approaches to enhance the capability of SCLs to load drugs and control release may make these optical devices behave as advanced drug delivery systems, fulfilling the requirements of both chronic and acute ocular diseases. Among those approaches, the application oldie molecular imprinting technology during SCL manufacture enables the creation in the lens structure of imprinted pockets that memorize the spatial features and bonding preferences of the drug and provide the lens with a high affinity for a given drug. Imprinted SCLs could prolong the permanence of the drug in the precorneal area and provide sustained drug levels, increasing ocular bioavailability and avoiding systemic side-effects. In this review, the potential and the advantages/drawbacks of drug-imprinted SCLs are critically analyzed and examples of the application of the molecular imprinting technology to beta-adrenergic antagonist, antimicrobials, antihistamines and ocular comfort ingredients are shown.