An emulsion is best described as which of the following?

• A. A coarse dispersion of small globules of lipid in a vehicle immiscible (ex. Oil in Water)
• B. A homogeneous solution of oil in water
• C. A suspension of solids in a liquid
• D. A gel formed by lipid in water

Answer: (A)

An emulsion describes a mixture of two immiscible liquids where one liquid is dispersed as droplets within the other. In pharmaceutics, this means small globules of lipid (oil) are dispersed in a continuous vehicle that does not mix with the lipid, such as oil droplets in water. This creates a coarse dispersion rather than a single uniform phase. Emulsions are distinct from true solutions (which would require dissolving the liquids into one another), from suspensions of solids (where solid particles are dispersed, not liquid droplets), and from gels (which are semi-solid networks). Emulsions are typically stabilized by emulsifying agents to prevent droplet coalescence, and can be oil-in-water or water-in-oil types.