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. During formulation development, the excipients are chosen carefully so that the active ingredient can reach the target site in the body at the desired rate and extent.
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.