Comparison
GHRP-6 vs. Ipamorelin
Two peptides side-by-side — identity, evidence base, legal status and known adverse events.
Identity
Category
Growth
Growth
CAS no.
87616-84-0
170851-70-4
Molecular weight
873.02 g/mol
711.86 g/mol
Half-life
0.4 h
2 h
Sequence
His-D-Trp-Ala-Trp-D-Phe-Lys-NH2Aib-His-D-2-Nal-D-Phe-Lys-NH2Mechanism of action
GHRP-6
GHRP-6 is a high-affinity agonist of the growth-hormone secretagogue receptor 1a (GHSR-1a) — the same receptor later shown to bind the endogenous hormone ghrelin. The identification of GHRP-6 as a pharmacological anchor led to cloning of GHSR in 1996 and the discovery of ghrelin itself in 1999. GHRP-6 stimulates pituitary GH secretion via a pathway independent of GHRH and can be combined synergistically with GHRH. Via GHSR in the hypothalamus it additionally activates NPY/AgRP neurons, producing an orexigenic (appetite-stimulating) effect in animal models.
Ipamorelin
Ipamorelin is a selective agonist at the GH secretagogue receptor (GHSR-1a). Compared to GHRP-2 and GHRP-6 its selectivity for the growth-hormone axis is higher; ACTH, cortisol and prolactin are not significantly stimulated in clinical studies. This selectivity was the main reason for its development over older GHRPs.
Evidence base
Highest evidence
Human trial
Human RCT
Studies
4
4
of which in humans
2
3
Effects recorded
4
3
Open conflicts
1
1
Documented adverse events
2
1