Hexarelin — Research Dossier
Evidence grading
Class
GHS-R1a agonist
Synthetic hexapeptide, GHRP family
GH potency
Highest of traditional GHRPs
Confirmed in head-to-head human pharmacology
Secondary target
Cardiac CD36
GH-independent cardiovascular research line
FDA approval
None
Not approved for any indication
Hexarelin produces the strongest acute GH response of the traditional GHRPs — confirmed in head-to-head comparison — paired with greater cortisol and prolactin elevation than more selective analogues and questions about desensitisation on repeated dosing.
Hexarelin is a synthetic hexapeptide GH secretagogue acting at the ghrelin receptor (GHS-R1a), part of the GHRP family alongside GHRP-1, GHRP-2 and GHRP-6. It is most studied for its GH-releasing potency — generally reported as the strongest acute GH response among the traditional GHRPs in head-to-head comparison — and for a distinct cardiovascular interaction not shared equally by other GHRPs.
Its stronger GH response comes paired with a less selective hormonal profile: hexarelin elevates cortisol and prolactin more than GHRP-2 or ipamorelin. It also binds the cardiac scavenger receptor CD36 independently of the GH axis, the basis for a separate cardiovascular research line.
“Head-to-head comparison in healthy volunteers showed hexarelin produced GH responses exceeding those of maximal-dose GHRH, confirming its position as the most potent acute GH releaser among the traditional GHRPs.”
— Arvat E et al., Eur J Endocrinol 1997
Mechanism
Hexarelin stimulates pulsatile GH release via GHS-R1a and somatostatin antagonism. Two features set it apart from other GHRPs: it produces the strongest GH response in head-to-head testing, but it also elevates cortisol and prolactin more than GHRP-2 or ipamorelin — reducing hormonal selectivity. Hexarelin additionally binds the cardiac scavenger receptor CD36, the basis for a research line into direct cardioprotective effects independent of the GH axis.
Evidence base
GH potency (established)
Arvat et al. (1997) included hexarelin in the definitive head-to-head human comparison with GHRP-2, GHRH, TRH and hCRH, confirming GH responses exceeding maximal-dose GHRH — the strongest signal among the tested secretagogues. This study also confirmed the greater cortisol and prolactin elevation relative to GHRP-2.
Cardiovascular / CD36 (largely preclinical)
Bodart et al. (2002) demonstrated that hexarelin mediates cardiovascular effects through CD36, a cardiac scavenger receptor, in a GH-independent manner. This mechanism is the basis for research into cardioprotective effects. The human cardiovascular evidence remains primarily pharmacological rather than efficacy trial data.
Tolerance caveat
Repeated administration of hexarelin has been associated with attenuation of the GH response (desensitisation) in parts of the literature — a practical limitation relative to secretagogues such as ipamorelin and CJC-1295, where sustained pulsatile stimulation without tolerance is the documented profile.
Regulatory status and evidence grade
Hexarelin is not approved by the FDA, MHRA, or EMA for any indication. As a GH secretagogue it is prohibited by WADA under category S2. Material supplied for laboratory work is research-use only.
Evidence grade: Phase II. GH-releasing potency is confirmed in controlled human pharmacology. The cardiac/CD36 line is mechanistically interesting but largely preclinical; the cortisol/prolactin elevation and reported desensitisation are meaningful caveats, and there are no registrational efficacy trials.
See also
References
- 1
Arvat E, Maccagno B, Ramunni J, et al. The GH-releasing activity of GHRP-2, hexarelin and GH-releasing hormone in humans. Eur J Endocrinol. 1997.
- 2
Deghenghi R, Cananzi MM, Torsello A, et al. GH-releasing activity of hexarelin, a new growth hormone releasing peptide, in infant and adult rats. Life Sci. 1994.
- 3
Bodart V, Bouchard JF, McNicoll N, et al. Identification and characterization of a new growth hormone-releasing peptide receptor in the heart. Circ Res. 2002.
- 4
Bowers CY, Momany FA, Reynolds GA, Hong A. On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone. Endocrinology. 1984.
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