Multiple emulsions can also be used for the encapsulation of peptides/proteins and hydrophilic drugs. They also have applications in cosmetics. Oil-in-water-in-oil (o/w/o) type multiple emulsions on the other hand consist of very small droplets of oil dispersed in the water globules of a water-in-oil emulsion.īoth water-in-oil-in-water (w/o/w) and oil-in-water-in-oil (o/w/o) multiple emulsions are of interest as delayed- and/or sustained-action drug delivery systems. Oil-in-water-in-oil (o 1/w/o 2) emulsion.Įmulsifying a w/o emulsion using water-soluble surfactants (which stabilize an oily dispersed phase) can produce w/o/w emulsions with an external aqueous phase, which generally has a lower viscosity than the primary w/o emulsion.Water-in-oil-in-water (w 1/o/w 2) emulsion.They can be considered as emulsions of emulsions. Multiple emulsions are emulsions whose dispersed phase contains droplets of another emulsion. Read Also: Advantages and Disadvantages of Pharmaceutical Suspensions Multiple emulsions Thus, the use of a lipophilic emulsifier enables the formation of w/o emulsions with the oil phase as the external, continuous phase. The w/o emulsions are used mainly for external applications and may contain one or several of the following emulsifiers: calcium palmitate, sorbitan esters (Spans), cholesterol, and wool fats. A lipophilic emulsifier is used for preparing w/o emulsions. In a water-in-oil (w/o) emulsion, the aqueous phase is dispersed as globules in the oil continuous phase. Read Also: Advantages and Disadvantages of Pharmaceutical Emulsions Nano Emulsions (droplets size usually below 100 nm).Microemulsions (droplets size usually 100-600 nm).Mini emulsions (droplets size usually 0.1–10 µm).
Macro emulsions (droplets size usually exceeds 10 mm).However, depending upon the need, more complex systems (referred to as “double emulsions” or “multiple emulsions”) in which the oil-in-water or water-in-oil emulsions are dispersed in another liquid medium can be formulated.īy considering particle size, pharmaceutical emulsions can be The process of formation of an emulsion is termed emulsification. Emulsions are liquid disperse systems consisting of at least two immiscible liquids (or two liquids that are saturated with each other), one of which is dispersed as small globules (internal or dispersed phase) within the other liquid phase (external or continuous phase), generally stabilized by a third substance called emulsifying agent.
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