Microemulsion, a stunning potential
Microemulsions are thermodynamically stable systems formed spontaneously by gentle mixing of their components: oily vehicle, surfactant, co-surfactant, and water. Due to their low viscosity, transparency and low residue forming properties, microemulsions are suitable to apply on large skin surfaces and/or hair bearing areas.
Pseudo-ternary diagram, a powerful tool to determine microemulsion composition
If the process is of utmost simplicity as it only consists in low speed stirring, determining the exact proportion of each component of a microemulsion is a bit more time demanding. First, depending on the API solubility in individual excipients, select the most appropriate oil and surfactants. Then, build a pseudo-ternary phase diagram and determine the respective concentrations of the components yielding a microemulsion.
Considering microemulsions as finished or intermediate products
Labrasol® is a liquid oil-in-water (O/W) surfactant with excellent solubilizing capacity. It is often used in combination with a cosurfactant such as Plurol® Oleique CC 497, although other co-surfactants can also be used.
Labrafac™ Lipophile WL 1349 is an oily vehicle with emollient properties.
Microemulsions can be used as such, or for the preparation of innovative pharmaceutical foams.