Ethosomes as Promising Transdermal Delivery Systems of Natural‐Derived Active Compounds

Ethosomes are novel lipid‐based vesicular systems that demonstrate unique improvements in drug delivery with respect to other nanoparticles, especially for transdermal applications. Their high ethanol content strongly improves flexibility and deformability, which allows squeezing through the intercellular spaces without any drug leakage. The ethanol, moreover, contributes to increase the fluidity of the lipids of the cell membranes in dermal layers, allowing an in‐depth penetration of the nanostructures. Moreover, the high ethanol content of ethosomes allows the promotion of the encapsulation of either hydrophilic or lipophilic active agents, a feature particularly useful when it deals with natural extracts, a family of compounds characterized by a huge chemical variability. As a further advantage, being natural extracts often obtained in ethanol‐based solutions, their incorporation in ethosomes makes not necessarily expensive and time‐consuming procedures finalized at solvent removal. Following the initial exploitation of ethosomes, research focuses on the development of variants such as invasomes and transethosomes, which show improved drug encapsulation and delivery capacity. This review provides the state‐of‐the‐art on ethosomal research, with special attention on the encapsulation and delivery of natural extracts and their transdermal delivery.