Hexarelin: Hexapeptide GH Secretagogue with Cardiac Activity
Synthetic six-amino-acid ghrelin mimetic. Potent GH release and direct cardiac-receptor activity; investigational, never approved.
👥 Human studies
- Full name
- Hexarelin / Examorelin
- Class
- Ghrelin receptor agonist — peptide; also binds CD36
- Half-life
- ~55 minutes
- Route
- Subcutaneous, intranasal, IV
- Developer
- Pharmacia & Upjohn (discontinued)
- Regulatory status
- No approval; WADA-banned
What it is
Hexarelin is a synthetic hexapeptide closely related to GHRP-6. In addition to ghrelin-receptor agonism, it binds the scavenger receptor CD36 on cardiac tissue, prompting interest in cardiovascular protection alongside its GH-releasing properties.
How it works
GHS-R1a activation on pituitary somatotrophs produces a robust GH pulse, larger than GHRP-6 and comparable to GHRP-2. IGF-1 rises sustainedly with repeated dosing.
CD36 binding in cardiac tissue is independent of GH: pre-clinical studies show direct cardiomyocyte protection from ischaemia and modulation of vascular reactivity. Human cardiovascular outcomes have not been studied.
What the research shows
Short-term GH pharmacodynamic and cardiac pilot studies from the 1990s–2000s.
Imbimbo BP et al. (1994) — Phase 1 pharmacodynamics
Imbimbo B.P. et al., Eur J Clin Pharmacol 1994;46:421–425. 👥 Human studies
Healthy volunteers received single IV and SC doses of hexarelin.
GH peaks were 5–10× higher than placebo; effect was dose-dependent and reproducible.
Limitations: Acute only.
Broglio F. et al. (2002) — cardiac effects in heart failure
Broglio F. et al., J Clin Endocrinol Metab 2002;87:1505–1508. 👥 Human studies
Hexarelin administration in patients with mild heart failure improved left-ventricular ejection fraction acutely.
The effect appeared independent of the GH response, consistent with a CD36-mediated direct cardiac action.
Limitations: Small; acute effect only; no outcome data.
Safety and limitations
Acute safety mirrors other GH secretagogues: flushing, transient cortisol/prolactin rises, occasional nausea. Tachyphylaxis develops with repeated dosing within weeks.
No large clinical outcome data. WADA-banned.