A Comparative Review on Conventional and Advanced Ocular Drug Delivery Formulations

Amongst the various routes of drug delivery, the field of ocular drug delivery is one of the most interesting and challenging endeavors facing the pharmaceutical scientist for past 10-20 years. As an isolated organ, eye is very difficult to study from a drug delivery point of view. Despite these limitation, improvements have been made with the objective of maintaining the drug in the biophase for an extended period. Within the last few years, in response to the advent of potent and versatile therapeutic agents, the diversity of conventional ophthalmic formulations has gradually evolved, extending well beyond simple solutions, suspensions and ointments, now includes a variety of types of drug administration. In most recent publications, authors have broadened the notion of conventional ophthalmic delivery systems to encompass more than simple solutions and suspensions. While not strictly ‘conventional’, the ready availability of several commonly used drug vehicles suggests they have achieved acceptance, have been elevated to the category of conventional, and will be considered in this comparison. In this article, we have summarized the different types of commonly used ophthalmic formulations and compared the conventional formulations with the advanced formulation in many respects like their applicability, acceptance, characteristics and utility. This should also serve to put into perspective the discussions of more sophisticated components and elaborations.