Ipamorelin

Ipamorelin is a pentapeptide that selectively activates the ghrelin receptor (GHS-R1a) on the pituitary, triggering growth hormone release while leaving other pituitary hormone pathways largely undisturbed.

In the original 1998 study, ipamorelin stimulated GH release without raising ACTH, cortisol, or prolactin, and this selectivity held even at doses roughly 200 times higher than needed for GH release.

This set it apart from earlier growth hormone-releasing peptides and continues to drive research into more targeted GH secretagogues with fewer off-target hormonal effects.