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
Legal status
Full entries
Frequently asked questions
- What is the difference between GHRP-6 and Ipamorelin?
- GHRP-6 is classified as "Growth", while Ipamorelin is classified as "Growth". GHRP-6: Synthetic hexapeptide that founded the class of growth-hormone-releasing peptides (GHRPs). Cyril Bowers identified GHRP-6 in the late 1970s as the first orally and parenterally active GH secretagogue with no structural similarity to GHRH. Never approved as a medicine; downstream analogs (GHRP-2, hexarelin, ipamorelin) were pursued clinically. Ipamorelin: Synthetic pentapeptide and selective growth-hormone secretagogue. Developed at Novo Nordisk in the 1990s as a pentapeptide GHRP successor; clinical development was discontinued after phase 2 (post-operative ileus). This page contrasts both neutrally and source-based — with no usage or dosing recommendation.
- Which peptide is better supported by science, GHRP-6 or Ipamorelin?
- The highest available evidence level is "Human trial" for GHRP-6 and "Human RCT" for Ipamorelin. A higher evidence level means more robust data, but says nothing about suitability for an individual. The full body of evidence is on each peptide's own page.
- What is the legal status of GHRP-6 and Ipamorelin in Germany and the United States?
- Germany: GHRP-6 — Unapproved, Ipamorelin — Unapproved. United States: GHRP-6 — Unapproved, Ipamorelin — Unapproved. These are factual summaries with source and review date on the individual pages.