6AA Limited Human
Hexarelin
The most potent synthetic GHRP — triggers strong GH pulses and independently protects the heart via the CD36 receptor.
In Plain English: Hexarelin is a six-amino-acid synthetic peptide that acts on two receptor systems simultaneously: it fires the ghrelin receptor in the pituitary to produce a powerful burst of growth hormone, and it binds the CD36 scavenger receptor in the heart to deliver direct cardioprotection entirely independent of GH. Originally developed at Phase 2 for GH deficiency and congestive heart failure, it was never marketed but remains one of the most well-studied GHRPs in preclinical and early clinical literature.
Research Maturity
Limited Human (311 PubMed publications (1994–2026); 4 Phase 2 trials, rest largely preclinical+ Studies)
Quick Facts
Focus
Body Composition
Cardiac Research
Growth Hormone Modulation
Route
IV
SubQ
Origin
Fully synthetic hexapeptide developed in the early 1990s by Europeptides (R. Deghenghi) as a structural analogue of GHRP-6. The key modification — 2-methylation of the D-tryptophan at position 2 — confers approximately 10-fold greater GH-releasing potency versus GHRP-6 and superior metabolic stability. Reached Phase 2 clinical trials for GH deficiency and congestive heart failure; development discontinued before Phase 3.
Mechanism
Dual-receptor mechanism. (1) GHS-R1a agonism: binds the pituitary ghrelin receptor, mobilising intracellular calcium via PKC-dependent signalling to produce strong pulsatile GH release — more potent per microgram than GHRP-6, GHRP-2, or GHRH alone; synergistic with GHRH. (2) CD36 receptor activation: independently binds the CD36 scavenger receptor on cardiomyocytes and vascular cells, enhancing fatty acid oxidation, mitochondrial biogenesis via PGC-1α, and suppressing TGF-β1-driven fibrosis. CD36 knockout animals lose the cardioprotective effect while retaining GH release, confirming pathway independence. Stimulates cortisol and prolactin more than selective GHRPs (ipamorelin), especially at higher doses. Rapid receptor desensitisation (tachyphylaxis) observed within 1–2 weeks of continuous daily dosing.
Outcome
Peak serum GH and AUC dose-response, serum IGF-1, left ventricular ejection fraction (LVEF), infarct size (% of LV), cardiac fibrosis markers (collagen density, TGF-β1), plasma/liver triglycerides, body fat mass, lean mass, insulin sensitivity (HOMA-IR), cortisol and prolactin co-stimulation.
Safety Flags & Warnings
Receptor Desensitisation (Tachyphylaxis)
Cortisol & Prolactin Elevation
GH-Class Side Effects
Contraindicated in Active Cancer / History of Cancer
WADA Prohibited
No Long-Term Safety Data
Always consult a licensed physician. Research purposes only.
€6.0 / mg
