Comparison
GHRP-2 vs. GHRP-6
Two peptides side-by-side — identity, evidence base, legal status and known adverse events.
Identity
Category
Growth
Growth
CAS no.
158861-67-7
87616-84-0
Molecular weight
817.93 g/mol
873.02 g/mol
Half-life
0.5 h
0.4 h
Sequence
D-Ala-D-2-Naphthyl-Ala-Ala-Trp-D-Phe-Lys-NH2His-D-Trp-Ala-Trp-D-Phe-Lys-NH2Mechanism of action
GHRP-2
GHRP-2 binds with high affinity to the GH secretagogue receptor (GHSR-1a) in the pituitary and hypothalamus. Activation leads to rapid release of pulsatile growth hormone. Unlike GHRH, GHRP-2 acts via a separate pathway and can be combined synergistically with GHRH to elicit maximal GH responses in provocation tests.
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.
Evidence base
Highest evidence
Human trial
Human trial
Studies
4
4
of which in humans
4
2
Effects recorded
3
4
Open conflicts
0
1
Documented adverse events
1
2
Legal status
Full entries
Frequently asked questions
- What is the difference between GHRP-2 and GHRP-6?
- GHRP-2 is classified as "Growth", while GHRP-6 is classified as "Growth". GHRP-2: Synthetic hexapeptide of the GH secretagogue family. Approved in Japan as GHRP Kaken as a diagnostic test for GH deficiency. Not available as a medicine outside Japan. 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. This page contrasts both neutrally and source-based — with no usage or dosing recommendation.
- Which peptide is better supported by science, GHRP-2 or GHRP-6?
- The highest available evidence level is "Human trial" for GHRP-2 and "Human trial" for GHRP-6. 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-2 and GHRP-6 in Germany and the United States?
- Germany: GHRP-2 — Unapproved, GHRP-6 — Unapproved. United States: GHRP-2 — Unapproved, GHRP-6 — Unapproved. These are factual summaries with source and review date on the individual pages.