Advances in ophthalmic drug delivery

Abstract

Ophthalmic delivery of drug molecules has been a major challenge to both pharmacologists and drug delivery scientists.This is due to the unique anatomy and physiology of the eye.These challenges are primarily posed by various barriers of the eye, which are dependent upon the route of administration viz.topical, systemic, periocular and intravitreal.On the other hand, the principle challenge in treating ocular diseases, apart from overcoming barrier properties, is attainment of effective drug concentration at the drug target for prolonged periods of time, while minimising any side-effects.Recently, various ophthalmic drug delivery strategies have emerged.These include hydrogels, polymeric micelles, nanoparticles (NPs), implants, microneedles, iontophoresis, sonophoresis and so on, that offer a number of potential advantages as delivery systems for ocular administration, such as improving the bioavailability and sustained drug release and the reduction of side-effects.The successful introduction of themed issues in the Journal of Pharmacy and Pharmacology was initiated in 2005.Therefore, this issue, the ninth themed issue in the Journal of Pharmacy and Pharmacology, highlights recent advances in ophthalmic drug delivery.It is a summary of pertinent reviews and research papers submitted by the scientific experts in the field of ophthalmic drug delivery.Topical drug delivery remains a standard and acceptable mode of treatment of conditions of the anterior segment of the eye.Although very convenient for patients, topical administration of conventional drug formulations (e.g.eye drops) for the treatment of eye diseases requires high drug doses, frequent administration and rarely provides high drug bioavailability.In the present issue, Moosa et al., [1] Souza et al. [2] and Daull et al. [3] reviewed advances in topical drug delivery.Importantly, Moosa et al. [1] reviewed the topical administration of mini-tablets and other solid devices as an alternative drug delivery system to the anterior segment of the eye.This review highlights a number of articles that has indicated that the mini-tablets can have significant advantage in both in-vitro and in-vivo performance in comparison with topical liquid preparations.These dosage types can provide better patient convenience and compli-