ABSTRACT
Nanoemulsions (often referred to as submicron, ultrafine, or miniemulsions) are kinetically stable, heterogeneous dispersions with a mean droplet size ranging between a few hundred nanometers. These water-oil-surfactant ternary systems seem to be virtually stable in the thermodynamic sense due to their long-term physical stability. The nano-size of the droplets allows them to deposit uniformly on skin surfaces, resist gravitational effects and coalescence, as well as impart unique properties including optical clarity. Nanoemulsions are suitable for the efficient delivery of active ingredients through topical and transdermal routes. The large surface area and the low surface and interfacial tension of the systems facilitates superior penetration of drugs through the rough skin surface. By virtue of these unique qualities, nanoemulsions are believed to be efficient drug delivery vehicles for a variety of molecules, especially BCS class II and IV drugs. These systems could be applied through other non-invasive routes, namely ocular, nasal, ungual, and pulmonary to overcome the inherent challenges of drug delivery. Throughout this chapter, the authors discuss the formulation aspects of nanoemulsions and how these complex systems might overcome biopharmaceutical and other challenges of non-invasive drug delivery.
