Indispensable Potency (Biological Activity)

The measurement of potency (strength) is a regulatory requirement for all pharmaceuticals. For chemical drugs, the potency is determined by measuring the amount and purity of the active pharmaceutical ingredient that is present. Except for a few compendial small recombinant proteins (e.g., recombinant human insulin), measuring only the amount and purity is insufficient for determining the potency (i.e., biological activity) of biopharmaceuticals. The multiple factors that contribute to the challenge of measuring potency of a biopharmaceutical (whether recombinant protein, monoclonal antibody, viral vector, or genetically modified patient cells) will be examined in this chapter. The three major types of potency assays for biopharmaceuticals will be discussed: bioassay, surrogate assay, and assay matrix. Application of the minimum CMC regulatory compliance continuum risk-based approach will also be examined for the development, optimization, and validation of biopharmaceutical potency assays.