Author: Roman V. Moiseev, Peter W. J. Morrison, Fraser Steele, and Vitaliy V. Khutoryanskiy
development of advanced ocular formulations an important topic in pharmaceutical science, one of the ways to improve drug delivery to the eye is the use of penetration enhancers, these are defined as compounds capable of enhancing drug permeability across ocular membranes, overview of anatomical and physiological features of the eye and discusses some common ophthalmological conditions and permeability of ocular membranes use of penetration-enhancing compounds (cyclodextrins, chelating agents, crown ethers, bile acids and bile salts, cell-penetrating peptides, and other amphiphilic compounds) in ocular drug delivery, describing their properties and modes of action, ocular drug delivery, cornea, penetration enhancers, ocular conditions, ophthalmology, preferred method of ocular drug delivery is via topical application due to ease of access to the eye and the non-invasive nature of this administration route, Ocular drug penetration is possible via the transcellular pathway, i.e., into and through cells, or the paracellular route, i.e., between cells, or a combination of both pathways, Drug penetration enhancement can be achieved by inclusion of agents capable of modifying the tear film, mucous layer, and ocular membranes in a drug formulation, penetration enhancers are compounds that are able to enhance drug delivery across otherwise impermeable or limited permeability membranes such as the cornea, acting predominantly on the epithelia, penetration enhancers in ocular drug delivery facilitate delivery of active pharmaceutical ingredients through three main mechanisms or their combination Altering tear film stability and the mucous layer at the ocular surface, Modifying membrane components such as lipid bilayers of associated epithelial cells ,Loosening epithelial tight junctions, Penetration-enhancing excipients for use in ocular formulations should ideally have the following characteristics: they should be non-toxic and non-irritating, efficacious at low concentrations, fast-acting, and their effect should be reversible topical drug application is the most widely used treatment in ophthalmology due to its simplicity. However, some obstacles including low permeability of the cornea, tear reflex, blinking, and nasolacrimal drainage hamper drug delivery in this way. The analysis of physicochemical properties of various chemical compounds that cross ocular membranes, coupled with the histological structure of cornea, sclera, and conjunctiva, could be key in understanding the opportunities and obstacles in the ocular drug delivery. Penetration enhancers facilitate delivery of active pharmaceutical compounds through three main mechanisms or their combination: altering tear film stability and the mucous layer at the ocular surface, modifying membrane components such as lipid bilayers of associated epithelial cells, and loosening epithelial tight junctions.
