Nano – emulsions are quiet an importance nowadays in order to improve the technology of drug administration in various routes of administration. In this study it has been illustrated about the different routes of administration with the evaluation and characterisation. Different routes such as the nose to brain drug delivery system along with transdermal delivery and brain drug delivery system. The effect of surfactant and co- surfactant with its effect in the viscosity and concentration plays an important role in the formulation basis of the nano- emulsions are studied. It also shows the difference in characteristics between the nano-emulsion and micro- emulsion. The effectiveness in the enhancement of the technologies in nano-emulsion also is a great debate which has been studies. This study also illustrates the effect in the viscosity, porosity, zeta potential, kinetic model, invitro in vivo studies, viscosity and surface studies.