Growth & GH-Axis

GHRP-6

Growth-hormone secretagogue (GHRP) / ghrelin receptor agonist

An early-generation GH-releasing peptide referenced in foundational research.

Also referenced as: Growth Hormone Releasing Peptide-6, SKF-110679

6 aat½ Short, on the order of tens of minutes (reported approximately 15-60 minutes)

Overview

GHRP-6 is one of the earliest synthetic hexapeptide growth-hormone secretagogues, developed in the 1980s and instrumental in the discovery of the growth-hormone secretagogue receptor and its endogenous ligand ghrelin.

At a glance

ClassGrowth-hormone secretagogue (GHRP) / ghrelin receptor agonist

CategoryGrowth & GH-Axis

SequenceHis-D-Trp-Ala-Trp-D-Phe-Lys-NH2

Chain length6 amino acids

Molecular weight873.0 g/mol

Half-lifeShort, on the order of tens of minutes (reported approximately 15-60 minutes)

Typical formLyophilized powder

AliasesGrowth Hormone Releasing Peptide-6, SKF-110679

Use designationResearch / in-vitro only

Regulatory statusGHRP-6 is not approved by the FDA or EMA for any indication; it is used in research contexts only and is not an approved medicine.

What GHRP-6 does

GHRP-6 is a synthetic hexapeptide growth hormone-releasing peptide and an agonist of the ghrelin receptor (GHS-R1a); it was one of the first GHRPs discovered and much of the foundational understanding of ghrelin-mimetic GH release comes from work on it. It stimulates GH secretion by amplifying pituitary GH pulse amplitude and suppressing somatostatin, with IGF-1 rising downstream. Its most characteristic and strongly studied effect is potent appetite stimulation: GHRP-6 markedly increases hunger via ghrelin-receptor activation, more so than GHRP-2 or ipamorelin, which is a defining feature and the reason it is frequently referenced in appetite and gut-motility research.

Beyond GH release, GHRP-6 has drawn interest for GH-independent cytoprotective effects in preclinical work — including cardioprotective actions (partly via the CD36 receptor, shared with hexarelin) and tissue-protective effects in models of injury. It is less selective than ipamorelin, so it also elevates cortisol and prolactin to some degree. Like other short-acting secretagogues it preserves pulsatile GH release and is commonly paired with a GHRH analog for synergistic GH output.

The evidence base is largely preclinical plus early human GH-secretion pharmacology; GHRP-6 is not an approved drug, and its cytoprotective findings remain experimental.

Effects reported in research

Stimulated GH release via GHS-R1a agonism, amplifying pituitary pulse amplitude (human GH-stimulation and preclinical data).
Produced strong appetite stimulation through ghrelin-receptor activation — its most pronounced signature effect (more than GHRP-2/ipamorelin).
Raised downstream IGF-1 following GH release.
Showed GH-independent cardioprotective/cytoprotective effects in animal injury models (partly via CD36).
Elevated cortisol and prolactin modestly (less selective than ipamorelin).
Influenced gastrointestinal motility, consistent with ghrelin-pathway activation (preclinical).
Synergized with GHRH analogs for a larger combined GH pulse.
Remains research-use only; cytoprotective effects are preclinical.

Effects listed reflect findings reported in the research literature — many in animal or in-vitro models. Listing an effect is not a claim of efficacy or a therapeutic indication in humans.

Mechanism of action

GHRP-6 is an agonist of the growth-hormone secretagogue receptor (GHS-R1a, ghrelin receptor), stimulating pulsatile GH release from the pituitary. It is a strong stimulator of appetite via ghrelin-receptor signaling. It can also increase ACTH, cortisol, and prolactin secretion.

Mechanistic description reflects published research-literature understanding. Much peptide research is preclinical (in-vitro or animal-model); mechanism in humans may differ and is not established for many compounds.

What it's studied for

Research contexts in which GHRP-6 appears in the literature. Listing a research area is not a claim of efficacy or a therapeutic indication.

Key characteristics

One of the first GHRPs; historically key to identifying the ghrelin receptor
Strong appetite stimulation, more pronounced than most other GHRPs
Can raise cortisol, ACTH, and prolactin — less selective than ipamorelin
Ghrelin-receptor (GHS-R1a) agonist releasing GH in pulses
Hexapeptide of the GHRP family

Reported research dosing reference only

Educational reference, not dosing guidance. The figures below summarize amounts reported in published research and research-community protocols, provided for educational and research context only. They are not medical advice, not a recommendation, and not instructions for human use. GHRP-6 is a research compound.

GHRP-6 is referenced at roughly 1 mcg/kg or ~100 mcg per dose in the research literature. These are reference figures for research context only, not dosing guidance for humans.

Body-weight-scaled reference: ~1 mcg/kg per dose (ED50 near 0.7-1.0 mcg/kg)
Common research-protocol reference: ~100 mcg per subcutaneous administration

Reported frequencyReported 2-3 times daily in research protocols, often fasted

ReconstitutionLyophilized; typically reconstituted with bacteriostatic water for research use

Strongest appetite stimulation of the GHRP group; ~15-30 min half-life. Reference figures only, not human dosing guidance.

How it compares

GHRP-6 is historically foundational and produces the strongest appetite stimulation among common GHRPs, but is less selective (more cortisol/prolactin) than ipamorelin.

Commonly studied alongside

Compounds frequently researched together with GHRP-6 in the literature. Cross-referenced for research context — not a usage or combination recommendation.

CJC-1295 (with DAC)GHRP + GHRH analog is a synergistic GH-release research combination.CJC-1295 (no DAC)Short-acting GHRH analog co-studied with GHRP-6 to model pulsatile combined GH release.

Compare and calculate

Side-by-side pages for the pairings the literature already documents for GHRP-6, plus the unit-conversion reference for a reconstituted vial. Factual comparisons of documented characteristics — not a recommendation to combine or use any compound.

Handling & Stability

Lyophilized peptides are stored cold, protected from light, and reconstituted only at the time of intended in-vitro work.

Avoid repeated freeze-thaw cycles
Verify supplier lot and Certificate of Analysis
Follow institutional lab-safety protocols

Analytical & COA Concepts

Reputable research suppliers publish a third-party Certificate of Analysis per batch. Key analytical concepts referenced in COAs include:

Category Context

GHRP-6 sits in the Growth & GH-Axis area of the PeptiDex library.

Research Supplier Listing

Where researchers source GHRP-6

For researchers studying GHRP-6, third-party suppliers such as Practically Natty Peptides offer research-grade material, third-party tests every batch and provides Certificates of Analysis on request, and ship from the US.

View research-supplier listing →

Outbound link to a third-party research supplier. Inclusion does not constitute endorsement; all editorial content is developed independently.

Frequently asked questions

What is GHRP-6?

GHRP-6 is a synthetic hexapeptide growth hormone-releasing peptide and one of the earliest developed ghrelin-receptor (GHS-R1a) agonists. It stimulates pulsatile GH secretion from the anterior pituitary and served as a foundational research tool for characterizing the GHS-R pathway.

How does GHRP-6 differ from GHRP-2 and hexarelin?

All three share a related hexapeptide scaffold and act on the ghrelin receptor, but GHRP-6 is the least potent and produces the most pronounced appetite stimulation. GHRP-2 is more potent with more cortisol/prolactin effect, and hexarelin is the most potent of the group.

Is GHRP-6 known for stimulating appetite?

Yes. GHRP-6 is the GHRP most strongly associated with hunger in the research literature, reflecting robust ghrelin-receptor agonism. This property makes it of interest in appetite- and feeding-related research models.

Why is GHRP-6 studied with GHRH analogs?

GHRP-6 stimulates the ghrelin receptor while GHRH analogs like CJC-1295 or sermorelin stimulate the GHRH receptor. Combining the two pathways yields a synergistic GH pulse, a standard approach in GH-secretagogue research.

Is GHRP-6 an approved drug?

No. GHRP-6 is not an approved medication; it has been used extensively as a research peptide and is available only as a research chemical.

Answers are educational summaries of research-literature context and do not constitute medical advice. See the Research Library, COA guide, and Storage & Handling guide for more.

References

Primary literature indexed in PubMed for GHRP-6. Listing a study records that it exists and is indexed — it is not a claim of efficacy, a therapeutic indication, or an endorsement of its conclusions. Much of this literature is preclinical (in-vitro or animal-model).

Pattern-dependent suppression of growth hormone (GH) pulsatility by ghrelin and GH-releasing peptide-6 in moderately GH-deficient rats Endocrinology, 2003. PubMed 12960077
Growth hormone releasing peptide-6 acts as a survival factor in glutamate-induced excitotoxicity J Neurochem, 2006. PubMed 17076656

Each reference was checked against its PubMed record on 2026-07-28: the PMID resolves and the title, journal and year match. Where no indexed literature exists for a compound, PeptiDex says so rather than substituting a citation about a different molecule. See the editorial policy.