The Pharmaceutics and Compounding Laboratory
Suspensions

Suspensions

Suspensions possess certain advantages over other dosage forms. Some drugs are insoluble in all acceptable media and must, therefore, be administered as a tablet, capsule, or as a suspension. Because of their liquid character, suspensions represent an ideal dosage form for patients who have difficulty swallowing tablets or capsules. This factor is of particular importance in administration of drugs to children. Suspensions of insoluble drugs may also be used externally, often as protective agents.

In addition, disagreeable tastes can be masked by a suspension of the drug or a derivative of the drug, an example of the latter being the drug chloramphenicol palmitate. Finally, drugs in suspension are chemically more stable than in solution. This is particularly important with certain antibiotics and the pharmacist is often called on to prepare such a suspension just prior to the dispensing of the preparation.

Suspensions also possess some disadvantages relative to other dosage forms. The primary disadvantage is their physical instability; i.e., that they tend to settle over time leading to a lack of uniformity of dose. This can, however, be minimized by careful formulation and by shaking the suspension before each dose is delivered. An additional disadvantage is that the texture of suspensions may be unpleasant to patients and should be carefully considered during formulation.