Table 2.

Advantages of microemulsion (ME) formulation for topical delivery of drugs.

No.	Advantages of Microemulsions	Ref.
1.	Thermodynamic stability, induced by the S/CoS mixture that provides a low interfacial tension due to a monolayer formed at the contact of oil particles with the water particles.	[175]
2.	Spontaneous formation due to an easy preparation method, without energy consumption; economic manufacturing.	[176,177]
3.	Incorporation of both hydrophilic and lipophilic compounds, resolving the solubility drawbacks for poor soluble drugs; MEs promotes their delivery at skin site in accord with a proper diffusion process.	[177,178]
4.	The solubilization capacity for API and the superior bioavailability are proportional with a high concentration of the S/CoS mixture introduced in the system.	[179]
5.	A high required concentration of surfactant, in association with a cosurfactant assure an easy passage through stratum corneum, acting as penetration enhancers; the barrier effect will be diminished.	[177,180]
6.	The selected API in microemulsion formulation is protected against hydrolytic and oxidative processes, being incorporated as encapsulated particles in oil or water fine droplets; MEs have a superior stability with improvement in half life.	[177,179]
7.	Incorporating APIs that are usually formulated for oral dosage forms and can be adapted in skin target. In this manner, it can be avoided the first pass liver effect and serious adverse reactions, promoting a localized action, without systemic effects.	[181]