Ipamorelin

Ipamorelin is a synthetic pentapeptide growth hormone secretagogue (GHS) that selectively stimulates growth hormone release from the pituitary gland. It was developed by Novo Nordisk and is studied as a selective GHRP (growth hormone releasing peptide).

Unlike other GHRPs such as GHRP-6 and GHRP-2, ipamorelin did not significantly affect cortisol or prolactin levels in published animal studies. This selectivity is attributed to its specific interaction with the ghrelin/GHS receptor (GHSR) without activating other pathways that cause unwanted hormonal effects.

Ipamorelin's mechanism centers on the growth hormone secretagogue receptor:

GHSR-1a Activation Ipamorelin binds to the growth hormone secretagogue receptor (ghrelin receptor) in the pituitary, triggering a signaling cascade that results in GH release. The binding pattern is distinct from ghrelin itself, contributing to its selectivity.

Pulsatile GH Release Rather than causing a continuous elevation, ipamorelin stimulates GH release in a pulsatile manner that more closely mimics natural physiological patterns. This pulsatility is important for maintaining GH receptor sensitivity.

Receptor Selectivity In published studies, ipamorelin released GH without the rise in ACTH and cortisol seen with GHRP-6 and GHRP-2, which is why it is used as a selective tool compound.

Concentration-Dependent Response In published studies, GH release rises with concentration and then plateaus, which allows controlled comparisons between experimental conditions.