Ocular Drug Delivery: the Challenges, Current Status and Advancements

Ocular drug delivery is the most fascinating and challenging task faced by pharmaceutical researchers. One of the major barriers of ocular medication is to obtain and maintain a therapeutic level at the site of action for prolonged periods of time. Major problems encountered by conventional ocular dosage forms include rapid pre-corneal drug loss due to naso-lacrimal drainage; tear turnover and drug dilution resulting in poor bio-availability. Therefore, efforts to improve ocular drug bio-availability led to development of novel drug delivery dosage forms such as nano particles, liposomes, hydrogels, ocuserts and muco-adhesive formulations. Controlled drug delivery systems offer many advantages over conventional dosage forms in terms of improving drug bio-availability, reducing toxicity and decreasing dosage frequency.