Ipamorelin (INN) (development code NNC 26-0161) is a peptide-selective agonist of auxin releasing peptides/somatosecretin receptors (GHS) and somatosecretin. It is a pentapeptide with the amino acid sequence Aib-His-D-2-Nal - D-Phe -Lys-NH 2, derived from GHRP-1. Ipamorelin significantly increases plasma growth hormone (GH) levels in both animals and humans. In addition, ipamorelin stimulated weight gain in the animals. Like pralmorelin and GHRP-6, ipamorelin does not affect prolactin, follicle-stimulating hormone (FSH), luteinizing hormone (LH), or thyrotropin (TSH) levels. However, unlike pramoline (GHRP-2) and GHRP-6, but similar to growth hormone releasing hormone (GHRH), iparerelin does not stimulate the secretion of adrenocorticotropic hormone (ACTH) or cortisol and is highly selective for inducing GH secretion only. Ipamorelin was originally developed by Novo Nordisk and conducted phase II clinical trials on itself as a treatment for postoperative ilobstruction, but it was discontinued due to lack of efficacy. Ipamorelin has been used by athletes as a performance enhancing drug.