Suspensions

Products

Suspensions are commercially available as cosmetics, medical devices, and drugs. Typical examples of medicines are eye drop suspensions, antibiotic suspensions, nasal sprays with glucocorticoids and other drugs for ingestion, antacids, the activated charcoal suspension, injection suspensions and shaking mixtures.

Structure and properties

Suspensions are liquid preparations for internal or external use. They are heterogeneous mixtures of substances (dispersions). An insoluble solid (powder) is present dispersed in a liquid solvent. Suspensions are characterized by the fact that the solid settles over time. This process is called sedimentation. Suspensions may contain thickeners such as celluloses as stabilizers to counteract the formation of the sediment. They must be able to be shaken up again in the pharmaceutical industry. They must remain sufficiently stable to allow the dose to be measured. The smaller the particles, the slower the sedimentation (Stokes law). Some suspensions must be freshly prepared before administration, for example, using a powder and a solvent such as water. This can extend the shelf life of the drug. Suspensions may impart retardation because the active ingredient may be released from it with a delay.

Indications for use

Suspensions are readily used in pharmacy, for example, in infectious diseases, inflammation, allergies, eye diseases and skin diseases.

Dosage

According to the professional information. Due to sedimentation, the liquid suspensions must be shaken immediately before use! This will ensure a uniform concentration.

Adverse effects

Undesirable properties of suspensions include flotation (floating of particles on the surface of the solvent), pooling, and formation of a stable sediment at the bottom of the vessel.