Prolonged corticotropic action of synthetic human ACTH in man

The corticotropic activities of synthetic human ACTH (revised structure), synthetic porcine ACTH (unrevised structure) and synthetic 1-24ACTH were compared in 8 normal men by measuring the magnitude and duration of the elevation of plasma 11-hydroxy-corticosteroids following the injection of 1 mg of the peptides. The duration of response was significantly longer after human ACTH than following porcine or 1-24ACTH, although the initial responses were identical. This difference was noted after both intramuscular and intravenous administration. The data suggest that the carboxyterminal of the ACTH peptide is of some importance for biological activity and that biological species specificity may exist.