Bioassays product potency determined

The aim of this section is to cover approaches to assay selection, to provide an overview of the possible assay formats and to give a description of the most frequently used assay formats for potency determinations. Bioassays are developed and used for different purposes during drug discovery and development. Even though they can have the same assay format they have a different purpose in a product development cycle starting from target selection to clinical biomarkers. 

Methods to determine the potential biological activity of products obtained through recombinant DNA techniques are of fundamental importance. Despite the existence of numerous physicochemical techniques to characterize the protein product structure and the presence of contaminants, they provide little, if any, information about its biological potency. A bioassay is defined as a functional test, and no physicochemical test can measure the function. However, for some peptide hormones, which are less complex in structure than most cytokines, well defined physicochemical tests may be used to estimate biological activity for instance, the capillary electrophoresis analysis of a protein s isoform content if the specific activity of each one is known. 

A bioassay is an analytical procedure that uses a responsive biological system (biological function) to measure the biological potency of a product (Mire-Sluis et al., 1996). The most appropriate method to determine it is by comparing the biological activity of a sample with a well-characterized reference standard. 

Nomi, Nimi and Miyazaki (1966) reported that, upon incubation of supernatants from suspensions of S. griseus in glucose and sodium chloride, streptomycin production was observed. When the pH of the suspension fluid reached 6.8 to 7.0, the suspension was centrifuged and the supernatant removed. When the supernatant preparations were adjusted to a pH of about 9 2tnd shaken for 24 hrs. the antibiotic potency, as determined by bioassay, increased considerably. This increase in potency was inhibited by the addition of phosphate or EDTA to the supernatant solution. The system was heat labile above 50 C. 

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