What hexarelin is and how it works
Hexarelin is GHRP-6 with one modification: the D-tryptophan in position 2 carries a methyl group on its indole ring, giving His-D-2-Me-Trp-Ala-Trp-D-Phe-Lys-NH₂. That small change produced one of the most potent growth hormone (GH) releasers in the family. The compound was introduced in the early 1990s, much of its early animal and human pharmacology was worked out by research groups in Italy, and its international non-proprietary name is examorelin.
Like GHRP-6, its parent compound, hexarelin activates GHS-R1a, the ghrelin receptor, on the GH-producing cells of the anterior pituitary and in the hypothalamus, where it increases GHRH release and counters the inhibitory hormone somatostatin. In human studies its GH response was larger than the response to GHRH, and more than additive when the two were given together. It also raises prolactin, ACTH and cortisol somewhat, as the other early GHRPs do.
What sets hexarelin apart is a second binding site. From the late 1990s, researchers found that it binds heart tissue in a way the ghrelin receptor could not explain, and identified the binding protein as CD36, a class B scavenger receptor that also takes up oxidised LDL and long-chain fatty acids and is found on heart muscle cells, the lining of small vessels, platelets and macrophages. That gave a route to cardiovascular effects separate from GH, and led to hexarelin analogues designed to bind CD36 with little GH-releasing activity, some of which have been tested in mouse models of atherosclerosis.
What the research on hexarelin shows
Most of the heart data come from rats. In rats made GH-deficient, including animals whose pituitary gland had been removed, pretreatment with hexarelin protected the heart against injury from ischaemia and reperfusion, the damage that follows when blood flow stops and then returns. A rat without a pituitary cannot mount a GH response at all, so the protection had to come from elsewhere, and CD36 later supplied a candidate mechanism. Evidence level: rodent models, including isolated-heart experiments.
Small human studies explored the same idea. In Italian work, a single intravenous dose of hexarelin was followed by a rise in left ventricular ejection fraction in healthy volunteers and in patients with reduced heart function, and the effect did not appear to track the GH rise. These were acute measurements in small groups, closer to pilot pharmacology than to clinical trials, and they led to no cardiac indication.
The other well-documented property is desensitisation. When hexarelin was given repeatedly over weeks to months in human studies, the GH response became partly smaller and then recovered after a break from dosing. That has to be designed around in any repeated-dose study, and it limits what such a study can show. Our comparison of growth hormone secretagogues places hexarelin next to the other compounds in the class.
What remains unproven is any long-term benefit in people, for heart function, body composition or anything else. The heart story rests on rodent models and short human pilot measurements, and no outcome trial has been published.
Hexarelin doses used in published research
| Setting | Subjects | Route and schedule | Main read-out |
|---|---|---|---|
| Heart protection models | Rats, including rats without a pituitary | Repeated injections over several days before an ischaemia test | Heart function after ischaemia and reperfusion |
| Route comparison | Healthy adults | Intravenous, subcutaneous, intranasal and oral | GH response; much larger doses needed by mouth |
| Acute cardiac studies | Healthy volunteers; patients with reduced heart function | Single intravenous dose | Ejection fraction, GH |
| Repeated-dose studies | Adults | Repeated dosing over weeks to months | GH response over time |
| Treatment trials | None leading to approval | – | – |
Injected doses in the human studies were expressed in micrograms per kilogram of body weight, with much larger amounts needed by mouth because little of the peptide survives the gut. None of this established a therapeutic dose, and hexarelin has no approved use, so no validated human dose exists. The table summarises study designs; it is not a guide to use.
Hexarelin safety and side effects
What is known comes from short human studies and from animal work. There are no long-term safety data.
- Other pituitary hormones. Rises in prolactin, ACTH and cortisol accompany the GH response, as with GHRP-6 and GHRP-2.
- Desensitisation. The GH response weakens partly with prolonged dosing and returns after a pause, which makes the effect of any long run of doses hard to predict.
- Heart effects. Hexarelin acts on heart tissue directly. That is the research interest, but it also means cardiovascular effects cannot be assumed to be neutral in any model.
- Appetite. Ghrelin-receptor agonists can increase hunger; this has been studied less for hexarelin than for GHRP-6.
- Effects of raised GH. Fluid retention and reduced insulin sensitivity follow sustained GH excess. Repeated hexarelin exposure has not been studied long enough to rule them out.
Regulatory status of hexarelin in Europe
Hexarelin is not authorised as a medicine in the European Union and has no approved indication elsewhere. It reached clinical research in the 1990s but never the market. Research material carries no marketing authorisation and is not intended for human use; rules on possession and import differ between member states.
In sport, hexarelin is prohibited at all times under S2 of the World Anti-Doping Agency Prohibited List, where it appears among the growth hormone releasing peptides under its non-proprietary name, examorelin.
Sourcing hexarelin and checking quality
King Peptides does not stock hexarelin. The closest product in its range is the CJC-1295 + Ipamorelin Blend 5/5 mg, which combines a GHRH analogue with a different ghrelin-receptor agonist, ipamorelin, the most selective of the class. It is relevant to research on GH release. It is not a substitute for hexarelin in CD36 or heart work: neither component has been characterised as a CD36 ligand in the way hexarelin has.
For any product, the certificate should show HPLC purity of at least 99%, a lot number matching the vial, and a mass that fits the compound: about 887 Da for hexarelin, 711.9 Da for ipamorelin, and for CJC-1295 either 3647 Da with the DAC linker or 3368 Da without it, so check which form the product page states. King Peptides provides a lot-specific certificate with HPLC and mass spectrometry and dispatches from the Netherlands, with delivery usually 1–2 business days in the Netherlands and 3–5 business days elsewhere in the EU by the shop's own estimate, and no customs inside the EU. See our guides to reading a certificate of analysis and storing lyophilised peptides at −20 °C.
Hexarelin: frequently asked questions
How does hexarelin differ from GHRP-6? Structurally by one methyl group on the tryptophan in position 2. In practice it is the more potent GH releaser in human studies, and it is the GHRP most closely tied to CD36 binding and heart research.
Are hexarelin and examorelin the same compound? Yes. Examorelin is the international non-proprietary name; hexarelin is the name used in most of the research literature and on the WADA list.
Why does the GH response to hexarelin fade? The likeliest explanation is desensitisation of the ghrelin-receptor pathway under continued stimulation. In human studies the loss was partial and reversed once dosing stopped.
Does the heart research make hexarelin a heart medicine? No. The evidence is rodent models plus small, acute human measurements. No trial has shown a clinical benefit, and hexarelin is approved for nothing, anywhere.
Research use only. Hexarelin is described here for laboratory and scientific research. Research material carries no marketing authorisation, whatever the status of the molecule as a medicine elsewhere, and it is not intended for human or veterinary use. Nothing on this page is medical advice, and the dosing information above summarises published study designs. Always comply with the laws that apply in your country.