IPAMORELIN

Ipamorelin is a synthetic pentapeptide growth hormone secretagogue created through structural refinement of the earlier peptide GHRP‑1. It is recognised as the first growth hormone–releasing peptide (GHRP) receptor agonist designed with high selectivity, showing a specificity for growth hormone stimulation comparable to that of endogenous growth hormone‑releasing hormone (GHRH). In biochemical and cellular research environments, ipamorelin functions as an agonist at the ghrelin/growth hormone secretagogue receptor (GHSR‑1a), which is expressed on pituitary somatotrophs. Compared with earlier GHRPs such as GHRP‑2 and GHRP‑6, ipamorelin displays a distinct selectivity profile: experimental work has shown that, at concentrations effective for stimulating growth hormone release, it does not trigger adrenocorticotropic hormone (ACTH) or cortisol secretion. This characteristic makes ipamorelin a useful research compound for isolating growth hormone–specific signalling pathways without concurrent activation of the hypothalamic–pituitary–adrenal (HPA) axis. In controlled animal studies, ipamorelin has also been associated with dose‑dependent increases in longitudinal bone growth.