*An Update on Nanoemulsions Using Nanosized Liquid in Liquid Colloidal Systems DOI: http://dx.doi.org/10.5772/intechopen.84442*

protective mechanisms such as tear dilution, lacrimal drainage, protein binding and enzymatic degradation which are activated as soon as the ophthalmic solutions of the drug are applied, typically less than 3% of these topically applied drugs permeate the corneal epithelium, reach the aqueous humor and finally enter the systemic circulation. O/W Nanoemulsions (Oil in Water nano emulsions) have been researched for ocular administration to dissolve poorly soluble drugs, to increase absorption and also to attain prolong release profile [33].

Cationic submicron emulsions are promising carriers for DNA vaccines to the lung since they are able to transfect pulmonary epithelial cells thereby inducing cross priming of antigen-presenting cells and directly activate dendritic cells, resulting in stimulation of antigen-specific T-cells [35].

There might be adverse side effects of oils and surfactants on the alveoli of lungs. Hence extensive studies are required for the development of successful inhalable submicron emulsions for pulmonary delivery [32].
