"Excipient"

An excipient is a substance formulated alongside the active ingredient of a medication. They may be used to enhance the active ingredient’s therapeutic properties; to facilitate drug absorption; to reduce viscosity; to enhance solubility; to improve long-term stabilization (preventing denaturation and aggregation during the expected shelf life); or to add bulk to solid formulations that have small amounts of potent active ingredients (in that context, they are often referred to as "bulking agents", "fillers", or "diluents"). During the manufacturing process, excipients can improve the handling of active substances and facilitate powder flow. The choice of excipients depends on factors such as the intended route of administration, the dosage form, and compatibility with the active ingredient.

Virtually all marketed drugs contain excipients, and final drug formulations commonly contain more excipient than active ingredient. Pharmaceutical regulations and standards mandate the identification and safety assessment of all ingredients in drugs, including their chemical decomposition products. Novel excipients can sometimes be patented, or the specific formulation can be kept as a trade secret to prevent competitors from duplicating it through reverse engineering.^{[citation needed]}