Microemulsions as carriers for drugs and nutraceuticals

Microemulsions are potentially excellent carriers for bioactive molecules. They offer the advantage of spontaneous formation, ease of manufacture, thermodynamic stability, and improved solubilization of bioactive materials. This review explores some of the new trends in microemulsion research through analysis of some representative studies. The solubilization of different classic drugs, peptides, and nutraceuticals in various oral microemulsion compositions and microstructures was reviewed. It was found that even W/O microemulsions, which are expected to break upon dilution in the digestive tract, increase the permeability and bioavailability of drugs. Thus, it seems that component selection (the use of molecules that can act as permeability enhancers) is of great importance. Structures such as self-microemulsifying drug delivery systems (SMEDDS), W/O, bicontinuous, and O/W microemulsions, were closely examined, and their potential to serve as drug carriers was evaluated. It seems that for microemulsion systems to be used as vehicles for bioactive materials, the formulations should be based on SMEEDS, which form O/W upon dilution to a specific water content. U-type microemulsions are actually an improved SMEDDS formulation, capable of being diluted with any given water concentration. Much research is being conducted on microemulsion microstructure since there is an obvious direct connection between the microstructure, solubilization capacity, and bioavailability of the active molecules.