Hexarelin (His-DTrp-Ala-Trp-DPhe-Lys-NH₂) is a synthetic hexapeptide GH secretagogue and the most potent GHSR-1a agonist in clinical research — producing the highest GH pulse amplitude of any GHRP at equivalent doses. Unlike selective GHRPs such as ipamorelin (minimal cortisol/prolactin elevation), hexarelin activates both GHSR-1a (GH release) and a cardiac-specific CD36 receptor, giving it a unique cardiovascular research dimension independent of its GH-releasing properties. The CD36 interaction makes hexarelin the standard compound for studying peptide-based cardiac protection and is the mechanistic basis for its investigation in post-MI and cardiac function research.
Highest GH pulse
Among all GHRPs at equivalent dose
2 hr
Half-life SC
CD36
Cardiac hexarelin receptor — independent of GHSR-1a
6 aa
Hexapeptide — His-DTrp-Ala-Trp-DPhe-Lys-NH₂
≥99%
Purity — HPLC verified
Hexarelin — Specifications
Hexarelin — specifications
Property
Value
CAS Number
140703-51-1
Molecular Formula
C₄₇H₅₈N₁₂O₆
Molecular Weight
887.1 g/mol
Half-life
~2 hr (SC)
Class
Hexapeptide GHSR-1a agonist (GHRP)
Purity
≥99% HPLC verified
COA
Janoshik independent third-party
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Mechanism of Action — Hexarelin
Hexarelin activates two distinct receptor systems:
GHSR-1a (pituitary + hypothalamus): Gq/11-coupled → IP3/DAG → Ca²⁺ → GH release. Also activates at hypothalamic GHSR-1a → GHRH co-stimulation. Hexarelin has highest intrinsic efficacy among all GHRPs
CD36 (scavenger receptor B family): Expressed in cardiac tissue, macrophages, platelets. Hexarelin binds CD36 → cardioprotective signalling independent of GH/IGF-1 axis. PI3K/Akt pathway activation in cardiomyocytes
Cortisol/ACTH: Hexarelin activates ACTH release (unlike ipamorelin) — relevant as confound in GH studies, also studied for HPA axis research
Prolactin: Mild elevation — PRL receptor activation in breast/pituitary
Hexarelin vs Ipamorelin — choosing the right GHRP for your research
Ipamorelin is highly GHSR-1a selective — minimal cortisol, prolactin, or ACTH elevation. It is the cleaner tool for studying GH axis without HPA confounds. Hexarelin produces higher peak GH but with cortisol/prolactin/ACTH co-elevation — relevant confounds for studies measuring body composition, immune function, or stress responses. For maximum GH pulse amplitude studies or cardiac CD36 research, hexarelin is the tool. For clean GH secretagogue research without HPA activation, ipamorelin is preferred.
Key Research Studies & Clinical Data
Key hexarelin research
Study
Design
Key finding
Muccioli et al. 1998
Hexarelin binding in human cardiac tissue
CD36 identified as hexarelin cardiac receptor — first evidence of GH-independent cardioprotective mechanism
Bisi et al. 1999
Post-MI patients, hexarelin IV bolus
Improved cardiac output and EF in MI patients — CD36-mediated cardioprotection in humans
Hexarelin 100 µg/kg vs ipamorelin 100 µg/kg vs GHRP-6 100 µg/kg SC single dose in male rats. Serial GH serum draws (0, 15, 30, 60, 90, 120 min) — AUC, peak, duration. Defines relative potency.
Hexarelin 80 µg/kg IV 5 min before 30-min LAD ligation + 120-min reperfusion in rat. Infarct size (TTC stain), cardiac troponin I, echocardiography (EF, FS), CD36 expression (IHC), PI3K/Akt/Bcl-2 (WB).
Protocol 3: GH desensitisation
Hexarelin 80 µg/kg SC twice daily × 14 days. GH pulse amplitude on day 1 vs day 14 (blunting assessment). IGF-1, GHSR-1a mRNA in pituitary (qPCR) — quantifies receptor downregulation.
Protocol 4: HPA axis co-activation
Hexarelin vs ipamorelin equimolar SC in male rats. Serum GH, ACTH, cortisol, prolactin at 0/15/30/60/90 min post-dose — direct comparison of selectivity profiles.
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Frequently Asked Questions
What is hexarelin?
Hexarelin is a synthetic hexapeptide GHSR-1a agonist that produces the highest GH pulse amplitude of any GHRP. It also activates the cardiac CD36 receptor, giving it a cardioprotective mechanism independent of the GH axis — the basis for its use in cardiac protection research.
Why does hexarelin produce the highest GH pulse?
Hexarelin has the highest intrinsic GHSR-1a efficacy among synthetic GHRPs — higher receptor activation efficiency than GHRP-2, GHRP-6, or ipamorelin at equivalent doses. It also co-activates hypothalamic GHSR-1a → GHRH release, adding a second amplification pathway.
What is the CD36 cardiac receptor?
CD36 is a scavenger receptor (class B) expressed on cardiomyocytes, macrophages, and platelets. Hexarelin binds CD36 in cardiac tissue and activates PI3K/Akt cardioprotective signalling — reducing cardiomyocyte apoptosis in ischaemia-reperfusion models. This effect is independent of GH or IGF-1.
How does hexarelin differ from ipamorelin?
Ipamorelin is highly selective for GHSR-1a — minimal cortisol, ACTH, or prolactin elevation. Hexarelin produces higher GH but also elevates cortisol, ACTH, and prolactin via broader receptor activity. Hexarelin also has the CD36 cardiac mechanism that ipamorelin lacks.
What formats does QSC supply hexarelin in?
QSC supplies hexarelin as lyophilised research vials, ≥99% purity HPLC verified with Janoshik COA. Ships from QSC domestic warehouses in USA, EU, UK, Canada, and Australia.
Research Use Only: All QSC compounds are sold strictly for laboratory research purposes. Not for human use. Not approved by the FDA or equivalent regulatory bodies for human administration. All purchases confirm research intent and compliance with applicable local regulations.
