IN VITRO BIOASSAY OF CORTICOTROPIN: MODIFICATION AND STATISTICAL TREATMENT

Abstract
The in vitro bioassay of corticotropin, based on secretion of corticoids by isolated rat adrenals, was modified to allow the use of the 4 point assay design and the factorial analysis of Bliss and Marks for the determination of the relative potency, and its error, of an unknown preparation. The average index of precision, [lambda], of 24 assays was 0.15 [plus or minus] 0.007. Of several pituitary preparations only the corti-cotropic preparations are significantly active in this test, indicating that the method is specific for corticotropic activity. The assays of corticotropin by the in vitro method are of the same order as those by the adrenal ascorbic acid depletion method of Sayers, Sayers and Woodbury.