GHRP-6

The GHRP-6 evidence base cited here is 8 sources — 6 preclinical, 1 review. Critically, that evidence is almost entirely preclinical (animal and in-vitro) — no human clinical trials are cited, so efficacy and safety in people remain unproven. Regulatory status: Not FDA-approved.

• GHRP-6 is a synthetic hexapeptide and one of the first growth-hormone secretagogues (developed in the 1980s). It stimulates GH release by activating the ghrelin receptor (GHS-R1a) — a pathway distinct from, and synergistic with, GHRH analogs like CJC-1295.
• Its most distinctive practical effect is strong appetite stimulation (direct ghrelin-receptor activation) — intense hunger within ~15–20 minutes of injection.
• Unlike many research peptides, it has genuine human clinical data, including a Phase I safety trial and a 2024 acute-ischemic-stroke RCT, plus preclinical cardioprotective and cytoprotective findings.

GHRP-6 (Growth Hormone Releasing Peptide-6) is a six-amino-acid peptide that triggers the pituitary to release growth hormone by acting on the ghrelin/GHS-R1a receptor — a different mechanism from GHRH analogs, which is why the two classes are combined for a bigger effect. It was one of the earliest GH secretagogues developed and is among the better-characterized in humans.

Beyond GH release, it shows cardioprotective, wound-healing, and cytoprotective properties in preclinical and early clinical work. It is not FDA-approved; everything below is research context rather than medical guidance.

GHRP-6 is a synthetic hexapeptide (~873 Da, sequence His-D-Trp-Ala-Trp-D-Phe-Lys-NH₂) and a met-enkephalin analog. The D-amino acids at positions 2 and 5 (D-Trp, D-Phe) and the C-terminal amide give it proteolytic stability and the right shape to bind GHS-R1a.

It acts on both the ghrelin receptor (GHS-R1a) and the CD36 receptor, working through a PKC/calcium-dependent pathway that is separate from the cAMP pathway GHRH analogs use — the mechanistic basis for their synergy.

Injected subcutaneously, GHRP-6 is absorbed quickly and stimulates a pulse of GH release by activating GHS-R1a at both pituitary and hypothalamic sites. It requires endogenous GHRH tone for a maximal effect, which is exactly why combining it with a GHRH analog (CJC-1295/sermorelin) produces a substantially larger GH pulse than either alone — the two receptors are stimulated simultaneously through complementary pathways. Downstream, the GH pulse raises IGF-1. Its strong, direct ghrelin-receptor activity also drives pronounced appetite stimulation.

• Rapid subcutaneous absorption; distribution half-life ~7.6 minutes
• Time to peak: ~15 minutes; reported elimination figures vary
• Note an internal-source discrepancy: a ~20-minute half-life is sometimes cited, while mechanistic sources cite a ~2.5-hour elimination half-life — worth verifying against Bowers et al. (1991)

The half-life figures in circulation are inconsistent (~20 min vs ~2.5 hr). Treat the exact number as unsettled and confirm against the primary PK literature.

There is no approved dosing. Figures below are research/anecdotal, included for research context only.

• Commonly reported: ~100 mcg subcutaneously, 1–3× per day (morning, midday, bedtime)
• Often combined: ~100 mcg GHRP-6 + ~100 mcg CJC-1295 for a larger combined pulse
• Best on an empty stomach — ~2–3 hours after a meal and ~30 minutes before eating (food, especially fat/glucose, blunts the GH response)
• The bedtime dose is often emphasized to reinforce the sleep-associated GH pulse

• Reconstitute with bacteriostatic water added down the vial wall; swirl gently, never shake; solution should be clear (discard if cloudy or particulate).
• Refrigerate reconstituted solution at 2–8°C and use within ~30 days.
• A practical (non-definitive) potency cue: noticeable hunger within ~20 minutes of the first injection suggests active peptide — but HPLC/COA is still required for real verification.

A significant appetite increase is expected (ghrelin-receptor activation), not an adverse event. GHRP-6 transiently raises cortisol and prolactin at higher doses (usually not clinically significant below ~100–200 mcg), and prolonged use may raise blood glucose / reduce insulin sensitivity. It was found safe in a human Phase I IV dose-escalation trial. It is generally avoided with active cancer (GH/IGF-1 may promote tumor growth), and medical supervision is advised for anyone with diabetes or insulin resistance.

• Cytoprotection review (2017): across 1980–2017 literature, GHRPs including GHRP-6 acted as cytoprotective/pharmacological-preconditioning agents in cardiac, renal, pulmonary, and intestinal ischemia-reperfusion via PI3K/AKT1.
• Doxorubicin cardiotoxicity prevention (2024, rats): 400 µg/kg IP twice daily for 52 days completely prevented dilated cardiomyopathy and preserved LV systolic function (Bcl-2 upregulation, mitochondrial preservation).
• Phase I/II acute ischemic stroke (2024, human, 36 patients): EGF + GHRP-6 over 7 days showed favorable neurological/functional outcomes at 90/180 days and fewer serious adverse events than controls — a rare human RCT for a research peptide.

GHRP-6 is not FDA-approved and is sold as a research chemical for laboratory use only, not intended for human consumption. As a GH secretagogue it falls under sport anti-doping prohibitions — tested athletes should assume it is banned and verify with their governing body.

All citations link to the original source (PubMed, journal site, or regulatory filing). Independent research database — no vendor influence on what's cited.