An emulsion is a temporarily stable mixture of immiscible fluids such as oil and water, achieved by finely dividing one phase into very small droplets. Common emulsions can be oil suspended in water or aqueous phase (O/W) or water suspended in oil (W/O). Both O/W and W/O have unique applications and chemical properties and you can better choose the type you want to use if you know more about these differences.
(Oil-In-Water) O/W Emulsion
The oil in water emulsion is formed by combining oil, water, solid particles and a PH enhancing agent and mixing until the solid-stabilized oil-in-water emulsion is formed. Oil-in-water emulsions are mixable with water, non-greasy, non-occlusive and will absorb water. The dispersion medium in these emulsions is water; O/W emulsifiers keep oil drops packed in water. The low viscosity oil-in-water emulsion can be used to enhance the transportation of oil through a pipeline.
What You Need To Know About Oil-In-Water Emulsion
- Water is the dispersion medium and oil is the dispersed phase.
- They are non greasy removable from the skin surface.
- They are used external to provide cooling effect e.g vanishing cream.
- Water soluble drugs are more quickly released from o/w emulsion.
- O/W emulsions give a positive conductivity test as water is the external phase which is a good conductor of electricity.
- Preferred for internal use as bitter taste of oil can be masked.
(Water-In-Oil) W/O Emulsion
Water in oil emulsion (W/O) is one where the continuous phase is oil or lipid based and the internal (dispersed) phase is water. Water in oil emulsions are popular because they of their innate ability to provide better moisture protection than most standard oil in water (O/W) emulsions. W/O emulsions mix more easily with oils and have a high oil concentration. Common W/O emulsifiers are sorbitan stearate, lecithin, lanolin, sorbitan monoaleate and polyglyceryl oleate.
What You Need To Know About Water-In-Oil Emulsion
- Oil is the dispersion medium and water is the dispersed phase.
- They are greasy and not water washable.
- They are used externally to prevent evaporation of moisture from the surface of skin e.g Cold cream.
- Oil soluble drugs are more quickly released from W/O emulsion.
- W/O emulsions go not give a positive conductivity test as oil is the external phase which is a poor conductor of electricity.
- Preferred for formulations meant for external use like creams.
Also Read: Difference Between Colloidal And Suspension
Difference Between O/W And W/O Emulsion In Tabular Form
| BASIS OF COMPARISON | O/W EMULSION | W/O EMULSION |
| Description | Water is the dispersion medium and oil is the dispersed phase. | Oil is the dispersion medium and water is the dispersed phase. |
| Nature | They are non greasy removable from the skin surface. | They are greasy and not water washable. |
| Use | They are used external to provide cooling effect e.g vanishing cream. | They are used externally to prevent evaporation of moisture from the surface of skin e.g Cold cream. |
| Drugs | Water soluble drugs are more quickly released from o/w emulsion. | Oil soluble drugs are more quickly released from W/O emulsion. |
| Conductivity Test | O/W emulsions give a positive conductivity test as water is the external phase which is a good conductor of electricity. | W/O emulsions go not give a positive conductivity test as oil is the external phase which is a poor conductor of electricity. |
| Preference | Preferred for internal use as bitter taste of oil can be masked. | Preferred for formulations meant for external use like creams. |
ncG1vNJzZmiumauupbXFn5yrnZ6YsrR6wqikaJyZm7OmvsSnmp5lkprBuLHEp2SoZadirq%2BwjLBkqGWVosKtv8iopWg%3D