Compound profile
Hexarelin
Limited human dataAlso known as: Hexarelin acetate · Examorelin
A synthetic hexapeptide growth hormone secretagogue that activates the ghrelin receptor, producing one of the strongest GH releases of any peptide in its class. Distinct among GH secretagogues for a separate, GH-independent cardioprotective effect documented in animal models.
Overview
Hexarelin is a synthetic hexapeptide developed in the early 1990s as part of the same research program that produced GHRP-6, refined to bind the ghrelin receptor (GHS-R1a) with greater potency. Human pharmacology studies from Italian endocrinology groups in the 1990s established it as one of the most potent GH secretagogues tested, with intravenous doses producing GH release roughly twice that of GHRH alone.
What sets hexarelin apart from other GHRPs in the research literature is a body of animal work on a second, separate binding site, CD36, found on cardiac tissue and macrophages. Through this non-GHS-R1a pathway, hexarelin has shown cardioprotective effects in rodent models of ischemia and heart failure that appear to be independent of its growth hormone-releasing activity, a mechanistic split that has made it a recurring subject in cardiovascular peptide research separate from its bodybuilding-community reputation as a GH secretagogue.
It is not an approved drug anywhere and is sold exclusively as a research chemical. Its potency also comes with a tradeoff seen across the GHRP family: it raises cortisol and prolactin alongside GH, and repeated dosing can lead to receptor desensitization, meaning the GH response shrinks with continued use.
Mechanism (plain language)
Activates the ghrelin receptor (GHS-R1a) in the pituitary and hypothalamus to trigger strong GH release, and separately binds CD36 receptors on cardiac and immune tissue, a pathway linked to cardioprotective effects in animal studies independent of GH.
How it works
Like other GHRPs, hexarelin binds the ghrelin receptor on pituitary somatotrophs, triggering calcium influx and GH release through a pathway distinct from, and additive to, the GHRH receptor pathway that sermorelin and CJC-1295 use. Human dose-response studies found it produced GH release roughly twice as strong as an equivalent dose of GHRH, making it one of the most potent GH secretagogues tested in humans, whether given intravenously, subcutaneously, intranasally, or even orally, though oral bioavailability is very low.
Separately from GH release, hexarelin also binds CD36, a scavenger receptor expressed on cardiomyocytes, macrophages, and adipocytes that is unrelated to GHS-R1a. In rodent studies, activating this pathway has been linked to reduced cardiomyocyte death after ischemia-reperfusion injury, improved cardiac function after experimental heart attacks, and effects on PPAR-gamma signaling in fat and immune cells. Because these cardioprotective effects persist in models where GH release is blocked, researchers treat the GH-releasing and cardiac pathways as mechanistically separate, even though they come from the same molecule.
What research suggests
Human pharmacology studies from the 1990s confirm strong, reliable GH release across several routes of administration. The cardioprotective findings are almost entirely from rodent studies; there is no controlled human trial data testing hexarelin for cardiac outcomes.
Reported benefits
What studies, case reports, and the research literature describe, not guaranteed outcomes. The trials behind these findings are in the studies below.
Potent, reliable GH release
Human dose-response studies found intravenous hexarelin produced GH release roughly twice that of an equivalent GHRH dose, with high subcutaneous bioavailability.
Cardioprotection in animal models
Rodent studies report that hexarelin improves cardiac function, reduces cell death, and preserves electrophysiological properties of heart tissue after ischemia-reperfusion injury, through a CD36-mediated pathway separate from GH release.
Preserved response in some aging studies
Short-term intranasal and oral hexarelin dosing in older adults did not desensitize the GH response over the study period, in contrast to concerns about receptor desensitization with repeated GHRP use.
Uncertainties & risks
The cardiac benefit story is built almost entirely on animal data; no human cardiovascular outcome trials exist. Cortisol and prolactin elevation are more pronounced than with GHRH-class peptides, and it is not approved or regulated for human use anywhere.
Hexarelin's strong ghrelin-receptor activity comes with hormonal side effects beyond GH, most notably cortisol and prolactin elevation, which researchers have documented consistently across dosing studies and which distinguish it from GHRH-class peptides like sermorelin. Because it is unregulated, sourcing and purity of research-chemical hexarelin vary widely, and there is no long-term human safety data for repeated use. The cardioprotective research, while genuinely promising in animal models spanning multiple labs, has not been tested in human cardiac patients, so extrapolating those rodent findings to human heart health is not supported by current evidence.
Side effects
Commonly reported
- Cortisol elevation: Documented in human dosing studies, more pronounced than with GHRH-class peptides
- Prolactin elevation: Reported alongside GH release in human pharmacology studies
- Flushing and mild hunger: Reported shortly after dosing
Reported in the cited literature, not a complete list, and not medical advice. Individual responses vary; consult a qualified professional.
STACKD study summaries
Start with our in-house roundups, plain-language synthesis of the research, with primary sources cited at the bottom of each.
Primary sources
Secondary citations for verification. Prefer the STACKD summary above for context before opening these.