Ocular drug delivery - a look towards nanobioadhesives.

IMPORTANCE OF THE FIELD: A major challenge emanating in the design of topical ophthalmic preparations is their short precorneal residence time. Retention of a drug delivery system in the front of the eye is thus desirable. One solution identified to address this concern is a retentive system that can preferably be delivered in a liquid drop form and ultimately remain attached to the corneal tissue owing to incorporation of a bioadhesive component. Forward-thinking approaches are required to achieve advancements in this approach for the attainment of an effective drug concentration at the site of action. Accordingly, several investigators have identified the benefits of nanotechnology-based drug delivery systems for ophthalmic drug delivery. AREAS COVERED IN THIS REVIEW: A concerted effort was made to review critically all 'nanobioadhesives', that is, nanosystems designed for ocular drug delivery with the goal of attaining prolonged ocular retention, in a systematic, chronological manner, from their reported point of inception to the present. WHAT THE READER WILL GAIN: A perspective on possible future trends in this growing field of ocular drug delivery is formulated. TAKE HOME MESSAGE: The importance of and need for new developments in the field of ocular nanobioadhesives is emphasized.