Intravenous infusions are administered directly into the bloodstream, and thus do not pass through the protective filters of the digestive system before being circulated through somewhat vulnerable areas, such as the heart and lungs. A common risk from intravenous infusions is contamination by particles that are not visible to the eye.
Contamination can have many sources, including unwanted chemical reactions of the drug, incompatibility with other drugs or glass ware, rubber particles from the product's container, or precipitation of the drug. Precipitation is caused by low or decreased drug solubility, which can arise through too-high drug concentration, or through the solvent’s pH or ionic strength. If the drug is more lipophilic and hard to dissolve or disperse in water, it is more likely that particles may precipitate.
In addition to the health risks, there are also financial consequences that should be considered. Contamination by particles can lead to extended hospital stays and treatments, which generally carry high costs.
Therefore, for quality-control purposes, it is important to check for such unwanted particles.