Central Adrenal Insufficiency in Childhood Cancer Survivors Together by St. Jude Normal Physiology of ACTH and GH Release in the Hypothalamus and Anterior Pituitary in Man Endotext NCBI Bookshelf Ipamorelin is a pentapeptide. Five amino acids. That's it. But three of those five don't exist in nature. The sequence: Aib His D 2 Nal D Phe Lys, with a C terminal amide. Position 1 is aminoisobutyric acid the Normal Physiology of ACTH and GH Release in the Hypothalamus and Anterior Pituitary in Man Endotext NCBI Bookshelf