A Review Article on Ocular Drug Delivery Advances

The human eye is a sophisticated organ with distinctive anatomy and physiology that hinders the passage of drugs into targeted ophthalmic sites. Effective topical administration is an interest of scientists for many decades. Their difficult mission Is to prolong drug residence time and guarantee an appropriate ocular permeation. Several ocular obstacles oppose effective Drug delivery such as precorneal, corneal, and blood-corneal barriers. Routes for ocular delivery include topical, interatrial, intraocular, juxtascleral, subconjunctival, intracameral, and retrobulbar. More than 95% of marketed products exists in Liquid state. However, other products could be in semi-solid (ointments and gels), solid state (powder, insert and lens), or Mixed (in situ gel). Nowadays, attractiveness to nanotechnology-based carries is resulted from their capabilities to entrap Both hydrophilic and lipophilic drugs, enhance ocular permeability, sustain residence time, improve drug stability, and argument bioavailability. Different in vitro, ex vivo, and in vivo characterization approaches help to predict the outcomes of the Constructed nanocarriers. This review aims to clarify anatomy of the eye, various ocular diseases, and obstacles to ocular Delivery. Moreover, it studies the advantages and drawbacks of different ocular routes of administration and dosage forms.The ocular drug delivery Has been a major challenge to drug delivery scientists mainly due to its unique anatomy and physiology. One of the major problems Encountered by the conventional ocular dosage forms include the rapid precorneal drug loss due to its nasolacrimal drainage, tear Turnover and drug dilution resulting in poor bioavailability. These efforts lead to development of novel drug delivery dosage forms Such as nanoparticles, liposome, ocuserts, and mucoadhesive formulations. Controlled drug delivery systems offer many advantages . Over conventional dosage forms in terms of improving drug bioavailability, reducing toxicity and decreasing dosage frequency. Designing noninvasive sustained drug delivery systems and exploring the feasibility of topical application to deliver drugs to the Posterior segment may drastically improve drug delivery in the years to come. The ocular drug delivery deviates through a number of anatomical and physiological barriers, which have been a bottleneck for the Ophthalmologists. The ocular barriers, static and dynamic, decrease the absorption of the therapeutic agents and the entry of the xenobiotics. Thus, A conventional ocular dosage form has various disadvantages of its use in ocular diseases. Hence, an ideal ocular delivery system has always been Aimed, where the bioavailability of a drug is maintained for a longer period of time. The present review aims to focus on the drawbacks of the Conventional ocular therapy and the advantages of designing novel delivery systems, with their certain specific advantages in ocular Pharmacokinetics and the enhancement of bioavailability