Biological medicines are more complex than chemically-synthesised drugs. In most cases they cannot be characterised and measured using standard physicochemical means alone, so their biological activity must be measured using bioassays. Bioassays are tests that are carried out to determine the amount of a biologically active substance present in complex mixtures. They measure its effect on a biochemical process or on a biological system, such as cells, tissue or living organism.
World Health Organisation (WHO) biological reference materials (WHO international standards and reference materials) provide a common set of standards which are used to ensure the quality of biological medicines world-wide.
These international standards are considered to be the ‘gold standard’ against which regional, national and international laboratories and manufacturers calibrate their own working standards. They are calibrated in units of biological activity which are assigned following extensive studies involving multiple international laboratories.
Because bioassays use complex biological systems to test activity, they are variable from test to test. By using a biological reference material or standard of known activity or potency, bioassay results can be compared and calibrated to give a consistent result, no matter when or where the bioassay is performed.
In the case of diagnostic tests, the use of control samples of known activity allows the sensitivity and specificity of the test system to be monitored and quality assured.
NIBSC is a world leader in the production and distribution of a range of biological reference materials and standards including: