ipamorelin – Ipamoreliin acetate is the prototype of a novel series of hGH secretagogues that are analogs of ghrelin. There are other such peptidyl analogs including GHRP-2 and GHRP-6 as well as the non-peptide mimic of ghrelin called ibutamoren, or MK-677.
All of these GH secretagogues release GH with varying degrees of potency. However, in addition to hGH, the other secretagogues also increase prolactin (PRL) and cortisol secretion, indirectly by stimulating pituitary release of adrenocorticotrophin (ACTH).
On the other hand, ipamorelin has little tendency to release these secondary hormones and in fact is comparable to GHRH or sermorelin in that regard. This endocrine difference from the other GHRP’s is due to significant modification of its molecular structure, including addition of alpha-amino-butyric acid (Aib).
Thus, ipamorein is a high potency and efficacious ghrelin-type secretagogue having effects on plasma ACTH or cortisol levels comparable to the primary hGH releasing compound, GHRH. Consequently, it is the most selective GHRP receptor-active, GH secretagogue currently available.