Active ingredient

The dosage form for a pharmaceutical contains the active pharmaceutical ingredient, which is the drug substance itself, and excipients, which are the ingredients of the tablet, or the liquid in which the active agent is suspended, or other material that is pharmaceutically inert. Drugs are chosen primarily for their active ingredients. Patients often have difficulty identifying the active ingredients in their medication, as well as being unaware of the notion of an active ingredient. When patients are on multiple medications, active ingredients can interfere with each other, often resulting in severe or life-threatening complications. Many online services can help identify the active ingredient of most medications, such as the Medicines Database providing information on medications available in Australia. == Herbal medicine ==

In phytopharmaceutical or herbal medicine, the active ingredient may be either unknown or may require cofactors in order to achieve therapeutic goals. This leads to complications in labelling. One way manufacturers have attempted to indicate strength is to engage in standardization to a marker compound. Standardization has not been achieved yet, however, with different companies using different markers, or different levels of the same markers, or different methods of testing for marker compounds. For example, St John's wort is often standardized to the hypericin that is now known not to be the "active ingredient" for antidepressant use. Other companies standardize to hyperforin or both, ignoring some 24 known additional possible active constituents. Many herbalists believe that the active ingredient in a plant is the plant itself. == See also ==