The thrust for finding newer drug delivery systems for existing therapeutic molecules has opened a wide window for colloidal systems. Among many successful colloidal drug delivery systems, the microemulsions have been widely explored. Due to the presence of different domains of variable polarity in the microemulsions, they show a huge potential to be used as drug delivery vehicles for a variety of drugs. To thoroughly understand the drug delivery potential of microemulsion, it is necessary to know the possible phase transitions occurring in the system and the influence of drug on its microstructure. Recent years have witnessed the use of different microemulsions in developing a new generation of more effective drug delivery vehicles. The new methods are being developed to formulate formulations out of a seemingly endless number of combinations of surfactants and cosurfactants. This work is an extension in this direction wherein Tween-based microemulsion has been thoroughly...