Potency

Strength or effectiveness of a substance

Potency is defined in FDA Code of Federal Regulations, Part 21 Section 600.3, as “the specific ability or capacity of the product, as indicated by appropriate laboratory tests or by adequately controlled clinical data obtained through the administration of the product in the manner intended, to effect a given result.” In terms of active components in medications concentration and potency are used interchangeably. To determine the potency, specific analytical tests to quantify a quality of a substance called an "assay" is used. The USP offers monographs which outline the specific assay used to determine the potency of a given component.