Prolonged corticotrophic action of a synthetic substituted 1-18 ACTH.

The adrenocorticotrophic effects of a synthetic corticotrophin analogue, alpha(1-18) ACTH with D-serine(1), lysine(17), and lysine amide(18) substitutions has been studied. It is effective after both intramuscular and subcutaneous administration and compared with tetracosactrin depot (Synacthen depot, Cortrosyn depot) it has a similarly prolonged time course of action-about 24 hours after 0.5 mg and 30 hours after 1 mg. Unlike tetracosactrin depot, however, it is well absorbed when given intranasally and does not produce painful reactions at the site of injection. Its prolonged time course of action does not depend on a formulation designed to delay its release from the injection site but most probably on a decreased rate of degradation in the circulation.