Excipient

An excipient is a substance formulated alongside the active ingredient of a medication, included for the purpose of long-term stabilization, bulking up solid formulations that contain potent active ingredients in small amounts (thus often referred to as 'bulking agents', 'fillers', or 'diluents'), or to confer a therapeutic enhancement on the active ingredient in the final dosage form, such as facilitating drug absorption, reducing viscosity, or enhancing solubility. Excipients can also be useful in the manufacturing process, to aid in the handling of the active substance concerns such as by facilitating powder flowability or non-stick properties, in addition to aiding in vitro stability such as prevention of denaturation or aggregation over the expected shelf life. The selection of appropriate excipients also depends upon the route of administration and the dosage form, as well as the active ingredient and other factors. A comprehensive classification system based on structure-property-application relationships has been proposed for excipients used in parenteral medications. An excipient is a substance formulated alongside the active ingredient of a medication, included for the purpose of long-term stabilization, bulking up solid formulations that contain potent active ingredients in small amounts (thus often referred to as 'bulking agents', 'fillers', or 'diluents'), or to confer a therapeutic enhancement on the active ingredient in the final dosage form, such as facilitating drug absorption, reducing viscosity, or enhancing solubility. Excipients can also be useful in the manufacturing process, to aid in the handling of the active substance concerns such as by facilitating powder flowability or non-stick properties, in addition to aiding in vitro stability such as prevention of denaturation or aggregation over the expected shelf life. The selection of appropriate excipients also depends upon the route of administration and the dosage form, as well as the active ingredient and other factors. A comprehensive classification system based on structure-property-application relationships has been proposed for excipients used in parenteral medications. Pharmaceutical regulations and standards require that all ingredients in drugs, as well as their chemical decomposition products, be identified and shown to be safe. Often, more excipient is found in a final drug formulation than active ingredient, and practically all marketed drugs contain excipients.:1 As with new drug substances and dosage forms thereof, novel excipients themselves can be patented; sometimes, however, a particular formulation involving them is kept as a trade secret instead (if not easily reverse-engineered). The Federation of International Pharmaceutical Excipients Council (IPEC), a pharmaceutical regulatory non-profit, develops, implements, and promotes global use of appropriate quality, safety, and functionality standards for pharmaceutical excipients and excipient delivery systems. IPEC-Americas, along with its counterparts in Europe, China, and Japan serves as a primary international resource on excipients for its members, governments, and public audiences. IPEC works in collaboration with ExcipientFest to present topics ranging from regulatory affairs to research and development, often featuring speakers from FDA and other pharmaceutical organizations. Though excipients were at one time assumed to be 'inactive' ingredients, it is now understood that they can sometimes be 'a key determinant of dosage form performance'; in other words, their effects on pharmacodynamics and pharmacokinetics, although usually negligible, cannot be known to be negligible without empirical confirmation and sometimes are important. For that reason, in basic research and clinical trials they are sometimes included in the control substances in order to minimize confounding, reflecting that otherwise, the absence of the active ingredient would not be the only variable involved, because absence of excipient cannot always be assumed not to be a variable. Such studies are called excipient-controlled or vehicle-controlled studies. Antiadherents reduce the adhesion between the powder (granules) and the punch faces and thus prevent sticking to tablet punches by offering a non-stick surface. They are also used to help protect tablets from sticking. The most commonly used is magnesium stearate.