Definitions

The term "suspension" refers to a two-phase system consisting of a finely divided solid dispersed (suspended) in a liquid (the dispersing medium). Gels, magmas, and mucilages also contain suspended particles but are different from suspensions in that these suspended particles create a three-dimensional structure of interlacing particles or solvated macromolecules that restrict the movement of the dispersing medium.

Suspensions are intended for oral administration as sweetened, flavored formulations or for topical application where they are referred to as "lotions." Fluid liquid emulsions are also generically called lotions. Suspensions are also used as non-sweetened, non-flavored formulations for many parenteral routes of administration (e.g., intraocular, intranasal, IV, IM, ID, SC). Gels can be used to administer medications orally, topically, vaginally, and rectally.