Traversing the Skin Barrier with Nano-emulsions

Background: In recent years, colloidal delivery systems based on nano-emulsion are gaining popularity; being used for encapsulation and delivery of many drugs. This review therefore aims at summarizing various methods of nano-emulsion formulation and their use as a topical and transdermal delivery vehicle for a number of active pharmaceutical ingredients from different pharmacological classes. Methods: This article represents a systematic review of nano-emulsions for topical and transdermal drug delivery. A vast literature was searched and critically analysed. Results: Nano-emulsions are thermokinetically stable dispersion systems, which have been used in topical and transdermal delivery of a number of pharmaceutically active compounds. Nano-emulsions have a narrow droplet size range with tuneable surface properties, which make them an ideal delivery vehicle. Nanoemulsions have a number of advantages over conventional emulsions, including easy preparation using various low and high energy methods, optical transparency, high solubilisation capacity, high stability to droplet aggregation and the ability to penetrate the skin; thus allowing the transdermal delivery of drugs. Conclusion: This review indicated that nano-emulsions are promising vehicle for entrapping various drugs and are suitable for traversing the skin barrier for systemic effects.