Hexarelin
Synthetic hexapeptide ghrelin-receptor agonist from the GHRP family, researched for growth hormone release and cardiac signaling.
Overview
Hexarelin is a synthetic hexapeptide from the growth hormone-releasing peptide (GHRP) family, developed in the 1990s as a potent agonist at the ghrelin receptor (GHS-R1a). It stimulates growth hormone secretion with greater potency and longer duration than earlier GHRP compounds such as GHRP-6. Beyond the GH axis, hexarelin and related peptides have been studied in animal models for effects on the heart that appear partly independent of GH release.
Mechanism
Like other GHRP-class peptides, hexarelin binds the growth hormone secretagogue receptor 1a on pituitary and hypothalamic cells, activating signaling cascades that release GH. Distinct from this pathway, some studies report direct receptor-mediated effects on cardiac tissue, including protection against ischemia-reperfusion injury in rodent models, a finding attributed in part to ghrelin-receptor or related binding sites on cardiomyocytes. These cardiac effects are thought to involve ghrelin-receptor subtypes or additional binding partners in the myocardium, and hexarelin-derived analogs continue to appear in cardiovascular pharmacology research, positioning the peptide between classic GHRP tools and the endogenous hormone ghrelin.
Dosing
Research use is typically by subcutaneous injection, commonly once or twice daily in protocols, sometimes paired with a GHRH-class peptide. Dosing is protocol-specific, and figures should be sourced from the primary literature; there is no approved human indication.
Expected Effects
- robust transient increases in growth hormone
- elevated IGF-1 with repeated administration in research settings
- cardioprotective effects reported in rodent ischemia models
- smaller appetite and cortisol responses relative to some GHRP analogs in comparative studies
Side Effects & Tolerability
Reported effects resemble those of the GHRP class: transient hunger, rises in prolactin and cortisol, and injection-site reactions. As with other GH secretagogues, repeated use carries the theoretical risks of fluid retention and altered glucose metabolism, with limited controlled long-term data.
Storage
Lyophilized hexarelin should be stored desiccated, protected from light, and kept frozen at -20 deg C or below. After reconstitution, solutions should be refrigerated at 2-8 deg C and used promptly without repeated freeze-thaw.