Microemulsions: applications in transdermal and dermal delivery.

Microemulsions have gained much interest as second-generation colloidal carrier systems for the dermal/transdermal delivery of the various hydrophilic and lipophilic drugs. The advantages associated with microemulsions include spontaneity of formation, ease of manufacturing, high solubilization capacity, and improved drug stability. This review focuses on the excipients available for the formulation of topical microemulsions and the potential mechanisms responsible for improvements in the dermal/transdermal delivery of therapeutic agents. It also describes the in vitro and in vivo investigations reported for the various classes of therapeutic agents, along with the recent developments.