The reduction of the number of animals used in the biological assay of insulin.

The biological control of insulin is vital as it is administered daily to a large proportion of the population during the major part of their lives. The development of the biological assay of insulin will be described with the progressive evolution of methods eventually to dispense with the need for animals. From the quantal Mouse Convulsion Method using around 600 mice per sample to the quantitative Mouse Blood Glucose method using an average of 120 mice per sample in which the fall in the blood glucose levels is used to estimate the potency of insulin by its hypoglycaemic effect. This was followed by the development of the in vitro Radioreceptor Method which is a procedure based on competition between the binding of insulin and [125I]-insulin to cells of the cultured human IM-9 cell line. The production of highly purified insulin by the Pharmaceutical Industry has made possible the recent introduction of new High Performance Liquid Chromatography technology.