4 - Micro emulsion Formulation
The properties of the surfactant-oil-water are important in determining the formation of micro
emulsions.The formation of a micro emulsion depends on factors such as: 
(1) oil/surfactant and surfactant/co-surfactant ratio; (2) nature and concentration of the oil, 
surfactant, co-surfactant and aqueous phase; (3) pH; (4) temperature; and (5) hydrophilicity /
lipophilicity of polarity (Bolzinger, et al., 1998;
Salager, 2000).4.1 - Formulation Considerations
A micro emulsion generally consists of four different components, a lipophilic phase, a hydrophilic 
phase, surfactant and co-surfactant (Scriven, 1976).The quantities of different substances 
present, are also likely to change the properties, and are referred to as composition variables which 
can be expressed as weight, percentage or proportion (Salager, 2000).When four or 
more components are used pseudo-ternary phase diagrams are used to depict these systems in 
which each corner represents binary mixtures of two components such as surfactant/co-surfactant, 
surfactant/water, oil/drug, and water/drug mixtures.