Biological activity is a critical quality attribute; therefore, potency testing is an essential component of Quality Control in the manufacturing process. Potency tests, along with a number of other tests, are performed as part of product conformance testing, comparability studies, and stability testing. These tests are used to measure product attributes associated with product quality and manufacturing controls, and are performed to assure strength (potency) of products used during all phases of drug development and manufacturing.
Failure by the manufacturer to demonstrate the drug is meeting its pre-set FDA standards of potency or it is showing to be unstable during the manufacturing process will result in the non-release of products. A drug product is considered unstable when the drug substance (active ingredient) loses sufficient potency to adversely affect the safety or efficacy of the drug or falls outside of its labelled specifications. Drugs are considered stable if the active ingredient can maintain its strength at the level specified on the label for the maximum anticipated shelf-life.