Source:http://linkedlifedata.com/resource/umls/id/C1372955
NCI: The pharmaceutically active components of a preparation.,HL7V3.0: <p><b>Definition:</b>a therapeutically active ingredient (player) in a mixture (scoper), where the mixture is typically a manufactured pharmaceutical. It is unknown if the quantity of such an ingredient is expressed precisely in terms of the playing ingredient substance, or, if it is specified in terms of a closely related substance (active moiety or reference substance).</p>