TYPES OF EMULSIONS

An emulsion may be prepared from any two immiscible liquids but in pharmacy one phase is usually water.

Oil in water emulsions

These consist of oil droplets dispersed throughout an aqueous continuous phase.

Examples:

Medicinal emulsions mostly for oral use

Rubber latex

Egg yolk

Milk

Vanishing creams

Water in oil emulsions

These consist of water dispersed throughout a continuous oil phase

Examples:

Oily calamine lotion

Hydrous ointment

Cold creams

Multiple Emulsions

It is possible to prepare oil in water emulsion in which water globules are dispersed within the oil globules so that the system may be designated as water in oil in water

Medicinally used emulsions for oral administration are usually oil in water type and require oil in water emulsifying agent. These include synthetic non-ionic surface active agents, acacia, gelatin and tragacanth.

Externally applied emulsions may be oil in water or water in oil. Intravenous emulsions may be oil in water while intramuscular emulsions are water in oil or oil in water.

Water in oil emulsions are used almost exclusively for external application and may contain one or several of the following emulsifiers such as calcium palmitate, spans, cholesterol wool fat.