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").
The choice of excipients depends on factors such as the intended route of administration, the dosage form, and compatibility with the 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.
Materials used for enteric coatings include fatty acids, waxes, shellac, plastics, and plant fibers.
Small amounts of colouring agents are easily processed by the body, although rare reactions are known, notably to tartrazine.
[5] Examples of disintegrants include: Flavours can be used to mask unpleasant tasting active ingredients and improve the acceptance that the patient will complete a course of medication.
[5] Common minerals like talc or silica, and fats, e.g. vegetable stearin, magnesium stearate or stearic acid are the most frequently used lubricants in tablets or hard gelatin capsules.
For example, extended mixing of lubricants during blending may results in delayed dissolution and softer tablets, which is often referred to as "over-lubrication".
[5] In liquid and gel formulations, the bulk excipient that serves as a medium for conveying the active ingredient is usually called the vehicle.