Comparison of the corticotropic action of two synthetic, substituted analogues of ACTH: ACTH1--17 and ACTH1--18.

The effect of a recently synthesized analogue of ACTH, Ala1, lys17-ACTH(1-17-4-amino-n-butylamide; (ACTH1-17) upon serum cortisol levels in 9 healthy males was compared with that of ACTH1-18, D-ser1-lys17, 18-ACTH(1-18). Both compounds induced an identical rise in serum cortisol which lasted for at least 8 hours. It is concluded that the amino acid in position 18 is not essential for the corticotropic properties of the synthetic heptadecapeptide. The prolonged effect of these compounds indicates a potential therapeutic significance for ACTH analogues of low molecular weight.