Creaming, the separation of two liquids from one another, is characteristic of
emulsions. Shaking readily disperses the creamed emulsion. Settling of suspensions is
similar to this creaming, because after the settled suspension is shaken a few times it is
again suitable for use.
emulsion permanently separates into its two phases and no amount of shaking will
redistribute them. The same is true of suspensions that coalesce. The particles are no
longer surrounded by a coat of water or other liquid. They form into tight aggregates
that do not satisfactorily redisperse in shaking.
4-12. DISPENSING SUSPENSIONS
Since all suspensions contain insoluble dispersed particles, they must be
dispensed with "Shake Well Before Using" labels. Regardless of how perfect your
preparation may be or how long it has stood up on the shelf without noticeable settling,
sedimentation will occur eventually. When you hand the prescription to your patient,
call attention to the "Shake" label and verbally repeat the "Shake" instructions so that
there is not a doubt that the contents must be vigorously shaken before each dose or
application is withdrawn. Point out to the patient any special storage directions. In
dispensing all suspensions, instruct the patient NOT to refrigerate, except for antibiotics
must be dispensed in amber bottles and the patient must be instructed to store them
away from light. Those affected by heat should be stored away from heat, but not in a
A mixture is an aqueous preparation containing suspended insoluble material.
Mixtures too are intended for internal use. They often contain no agent to stabilize the
suspension. The only official mixture is Kaolin Mixture with Pectin, NF. (The word
mixture is frequently used by pharmacy personnel to refer to any aqueous preparation.)