An overview of the strengths and limitations of biological assays in quality control

Biological assays have been an integral part of the regulation of biological products in the United States since licensing of the first product in 1902. Bioassays have been used along with other methodologies in the assessment of identity, purity, safety, potency and stability. The technology of production, i.e. normal or recombinant, has not altered the use or value of these assays. Although many scientists and regulators would prefer to replace all in vivo bioassays with other assays, there is a reluctance to agree that this will be possible, at least in the near future. Scientific efforts are continuing to be focussed on the development of more precise, reliable and less cumbersome assay methods. This paper presents an overview of the strengths and limitations of bioassays as used in quality control, followed by a discussion of specific biological products as models for these principles.