Nanoemulsions are submicron sized emulsions that are under investigation as drug carriers for improving the delivery of therapeutic agents. These are the thermodynamically stable isotropic system in which two immiscible liquids are mixed to form a single phase by means of appropriate surfactant and cosurfactant. Nanoemulsion droplet sizes fall typically in the range of 20- 200nm and shows narrow size distribution. In this review attention is focused to give the brief regarding formulation aspect, method of preparation characterization techniques, evaluation parameters and various application of the nanoemulsions, several techniques are to be used for preparation of nanoemulsions like microfluidization, high pressure homogenization, low energy emulsification and solvent evaporation method and parameter that are to be used for its characterization like droplet size analysis, viscosity determination, drug content, refractive index, pH, zeta potential, Transmission electron microscopy, thermal stability, release and in vitro skin permeation study. These are applicable in drug targeting. Nanoemulsions have the potential in pharmaceutical industries because of the transparency at high droplet volume fraction, higher rate of bioavailability or diffusion and increased shelf life of the pharmaceuticals. Nanoemulsions are clear, thermodynamically stable, isotropic liquid mixtures of oil, water, surfactant and co-surfactant. These are oil-inwater (o/w) type of emulsions with the average droplet size ranging from 5nm to 100 nm. Reduction in droplet size to nanoscale leads to change in physical properties such as optical transparency and unusual elastic behaviour. Nanoemulsions have widespread applications in different fields such as pharmaceutics, food technology.

To overcome the drawbacks of conventional drug delivery systems, many strategies are available for the design and development of modified- release drug delivery formulations.  The primary purpose of these drug delivery devices is to improve the state of disease management by modifying the pharmacokinetic profiles of therapeutic agents normally administered as conventional tablets or capsules. Hydrophilic polymer matrix systems are widely used in oral controlled drug delivery because they make it easier to achieve a desirable drug - release profile, they are cost - effective, and they have broad US Food and Drug Administration (US FDA) acceptance. The aim of this present work is to formulate a sustained release matrix tablet of diltiazem by wet granulation method using various polymers such as HPMC, SCMC, Sodium alginate, PVP, Eudragit and Ethyl cellulose.

Skin acts as a major target as well as a principal barrier for topical/transdermal drug delivery. Despite the many advantages of this system, the major obstacle is the low diffusion rate of drugs across the stratum corneum. One simple and convenient approach is application of drugs in formulation with elastic vesicles or skin enhancers. Ethosomes are as novel vesicles in transdermal drug delivery show significant effects of drug penetration through the biological membrane with slight modification of well established drug carrier liposomes. Ethosomes are soft, malleable vesicles composed mainly of phospholipids, ethanol and water. The size of ethosome vesicles can be modulated from tens of nanometer to microns. The ethosomes can be prepared by Hot method, Cold method and optimized method. The evaluation parameters of ethosomes include visualization, vesicle size and zeta potential, entrapment efficiency. Ethosomes have been found to be much more efficient at delivering drug to the skin than either liposomes or hydroalcoholic solution. Hence it can be a   effective dermal/transdermal delivery of bioactive agents.