Hexarelin

Hexarelin (also known by the developmental name examorelin) is a synthetic six-amino-acid peptide that strongly stimulates the pituitary gland to release growth hormone by activating the ghrelin receptor. It was developed by an Italian pharmaceutical company and reached mid-stage human clinical trials for growth hormone deficiency and heart failure in the 1990s, but was never completed or brought to market. It is considered one of the most potent growth hormone releasing peptides in its class, and is also unusual among GHRPs for showing some direct effects on heart tissue in research settings. Today it is sold only as an unapproved research chemical, with community dosing information coming from bodybuilding and peptide forums rather than an approved clinical protocol.

Research snapshot

Peptide category	Synthetic growth hormone releasing hexapeptide (ghrelin receptor agonist), among the most potent in its class
Primary research interest	Growth hormone deficiency; congestive heart failure (unusual among GHRPs for showing direct cardiac tissue effects in research)
Highest available evidence	Tier 2 — reached Phase II human clinical trials but development was not completed
Human research available	Yes, Phase II trial data exists for growth hormone deficiency and congestive heart failure; program was discontinued before approval
Development status	Phase II; discontinued, never completed or brought to market
Regulatory status	Not approved by the FDA, EMA, or any comparable regulatory body; not legally sold in the US as an approved drug or dietary supplement

Technical identity

Primary name	Hexarelin
Alternative names	Examorelin (developmental name)
Peptide sequence	Not independently re-verified in this pass — commonly cited as His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2
Amino-acid length	6 (hexapeptide, includes non-standard lab-modified amino acids)
Molecular formula	Not independently re-verified in this pass
Molecular weight	Not independently re-verified in this pass
CAS Registry Number	Not independently re-verified in this pass
PubChem CID	Not independently re-verified in this pass
Peptide class	Growth hormone releasing peptide (GHRP), ghrelin receptor agonist family
Primary biological target	Ghrelin receptor (GHS-R1a); also shows some direct effects on cardiac tissue in research settings
Developer or originator	Mediolanum Farmaceutici (Italy)
Development status	Discontinued after Phase II; never approved or marketed

What is Hexarelin?

Hexarelin is a synthetic hexapeptide (six linked amino acids, including some non-standard, lab-modified ones) belonging to the growth hormone releasing peptide (GHRP) family. It works through the same general mechanism as GHRP-2 and GHRP-6, activating the ghrelin receptor to stimulate growth hormone release, but it is generally described in the pharmacology literature as the most potent GH secretagogue of the classic GHRP peptides in terms of the size of the GH pulse it produces per dose.

Hexarelin was developed by the Italian pharmaceutical company Mediolanum Farmaceutici in the early-to-mid 1990s. It was studied in human clinical trials, including dose-response studies in healthy volunteers and in specific patient populations, for two main purposes: as a potential treatment for growth hormone deficiency, and — more distinctively — for congestive heart failure, based on research suggesting hexarelin might have direct, GH-independent effects on cardiac tissue. It advanced as far as Phase II clinical trials for these indications but was not carried through to completion or market approval, and its clinical development appears to have been discontinued.

Because of this incomplete but genuine clinical history, hexarelin sits in an unusual place: it has real, published human dose-response pharmacology behind its GH-releasing effect, unlike some other research peptides, but it was never approved as a medicine for any use. Today it exists almost entirely as an unregulated “research chemical” sold by peptide vendors, used off-label in bodybuilding and anti-aging communities.

How does it work?

Plain-English explanation

Hexarelin works the same basic way as other GHRP-family peptides: it locks onto the ghrelin receptor and tells the pituitary gland to release growth hormone. It tends to produce a larger growth hormone release for a given dose compared with related peptides like GHRP-2 or GHRP-6, which is part of why it has drawn interest, but it has also been studied for a separate, more unusual reason — some research suggests it may act on receptors in heart tissue independent of its growth hormone effect, which is why it was investigated for heart failure rather than only for growth hormone deficiency.

Technical explanation

Hexarelin is a potent, selective GHSR-1a (growth hormone secretagogue receptor) agonist that stimulates pulsatile GH release from pituitary somatotrophs, acting through a pathway independent of, but synergistic with, hypothalamic GHRH signaling. Human dose-response studies established that hexarelin substantially and dose-dependently raises plasma GH, with effects described as amplified further when co-administered with GHRH. Beyond the classic GHSR-1a pituitary pathway, research (largely in animal and cell models, with some translational interest in humans) has proposed that hexarelin may act on a separate, less well-characterized cardiac receptor site distinct from GHSR-1a, producing effects on cardiac contractility and potentially cardioprotective signaling independent of growth hormone release; this is the basis for the historical Phase II congestive heart failure research, though this mechanism is less firmly established than its pituitary GH-releasing action.

Potential benefits and research applications

Growth hormone release (published human clinical evidence)

What is being investigated: hexarelin’s ability to provoke a strong, dose-dependent GH pulse. How the effect might occur: GHSR-1a agonism at the pituitary. Evidence: this has been demonstrated in multiple published human dose-response studies in healthy volunteers and specific patient groups (including elderly subjects) dating from the mid-1990s, several of which are indexed in PubMed. Strength: this is genuine human clinical evidence, among the stronger evidence bases of any peptide in the GHRP family. Limitation: these studies used controlled, short-term or single-dose administration to characterize the pharmacologic GH response; they were not long-term efficacy or safety trials for a therapeutic indication, and hexarelin was never approved based on them.

Growth hormone deficiency treatment (registered but discontinued human trials)

What is being investigated: whether hexarelin could serve as a therapeutic GH secretagogue for patients with growth hormone deficiency. How the effect might occur: sustained GHSR-1a stimulation raising GH and downstream IGF-1 over time. Evidence: hexarelin reached Phase II clinical trials for this indication. Strength: represents real, if incomplete, human clinical development. Limitation: development was discontinued and the compound was never marketed for this or any indication.

Congestive heart failure (registered but discontinued human trials, mechanistic evidence)

What is being investigated: whether hexarelin’s proposed cardiac receptor activity could benefit patients with congestive heart failure, independent of its growth hormone effect. How the effect might occur: through a proposed distinct cardiac binding site affecting cardiac contractility, separate from the pituitary GHSR-1a pathway. Evidence: reached Phase II trials; the underlying cardiac mechanism is supported mainly by animal and mechanistic research. Strength: is being investigated is the appropriate framing for the cardiac mechanism itself, while the clinical program for heart failure reached Phase II before being discontinued. Limitation: this indication was never approved, and the distinct cardiac receptor mechanism remains incompletely characterized.

Muscle gain, fat loss, and recovery claims (community-reported, largely unestablished)

What is being investigated: whether repeated hexarelin use improves body composition, recovery, or athletic performance in healthy, non-deficient adults. How the effect might occur: theoretically via sustained GH/IGF-1 elevation. Evidence: these claims are reported anecdotally in bodybuilding and peptide communities; this session did not identify controlled human trials of hexarelin for body-composition or performance outcomes in healthy adults. Strength: has not been established. Limitation: no peer-reviewed trial supports these specific outcome claims.

What dosage information circulates?

Figures in this section summarize amounts and schedules reported in published research or circulating online. Their inclusion documents what is reported and does not establish that a regimen is verified, safe, effective, or appropriate.

Amounts studied in human research

Published human dose-response studies of hexarelin exist, including work examining its GH-releasing activity in healthy volunteers, a specific dose-response study of GH, cortisol, and prolactin release, and studies in elderly subjects examining blunted responses restored by co-administration with arginine or GHRH (for example, research associated with PubMed IDs 7957536, 8954038, and 7962341). This session was not able to directly retrieve the specific numeric microgram or microgram-per-kilogram doses used in each of these individual studies from the primary sources during this research pass, due to access restrictions on the original articles; readers who need the exact dosing used in a specific hexarelin human study should consult that paper directly by its PubMed identifier rather than relying on a number repeated on a vendor or blog site.

Amounts studied in animal research

Not consistently reported. Hexarelin has been used in various animal studies of GH-axis pharmacology and, separately, in cardiac-mechanism research, but a consolidated, independently verifiable set of hexarelin-specific animal dosing figures was not identified in this research pass.

Practitioner and community-reported protocols

Peptide vendor sites and bodybuilding/anti-aging forums commonly describe hexarelin doses of roughly 100 to 200 micrograms per injection, subcutaneously, one to three times per day, often noted as needing a lower or less frequent dose than GHRP-2 or GHRP-6 because of its greater relative potency. This range is widely repeated online, but its original source could not be verified as tracing to a specific published protocol. Community sources also consistently discuss a concern specific to hexarelin: rapid desensitization or “tachyphylaxis,” meaning its GH-releasing effect is widely reported to weaken with continuous daily use faster than with other GHRPs, leading many community protocols to recommend shorter cycles or built-in breaks — this pattern is also referenced in some published pharmacology discussions of hexarelin, though the exact cycling schedules discussed in bodybuilding communities themselves are self-derived and not clinically validated.

Side effects, risks, and limitations

Human pharmacology studies of hexarelin have documented dose-dependent increases in cortisol and prolactin alongside its GH-releasing effect, generally more pronounced than with some other GHRP-family peptides. Community reports commonly describe increased hunger, water retention, and a sense of reduced effectiveness with continued daily use (desensitization), consistent with the tachyphylaxis pattern discussed above. Long-term safety data from repeated, unsupervised self-administration in healthy adults has not been established in controlled human research, since hexarelin’s clinical development did not proceed to that stage. As with any unregulated peptide sold through research-chemical channels, additional risks apply independent of the molecule’s own pharmacology: unverified purity, unverified concentration, contamination, and unsterile compounding are recognized general risks with unregulated injectable peptides and have not been evaluated for any specific vendor supply of hexarelin.

Regulatory and developmental status

Hexarelin was developed by Mediolanum Farmaceutici and reached Phase II clinical trials for growth hormone deficiency and congestive heart failure but did not complete development and was never approved or marketed for any indication in any jurisdiction. It is not approved by the FDA, the EMA, or any comparable regulatory body, and is not legally sold in the United States as an approved drug or dietary supplement. Material sold as “hexarelin” through research-chemical vendors is unapproved and not regulated for human use.

Frequently asked questions

What is Hexarelin?

Hexarelin (examorelin) is a synthetic six-amino-acid peptide that strongly stimulates growth hormone release by activating the ghrelin receptor. It reached Phase II clinical trials for growth hormone deficiency and heart failure but was never approved or marketed.

How does Hexarelin work?

It activates the ghrelin receptor (GHSR-1a) at the pituitary gland, triggering a strong pulse of growth hormone release. Some research also suggests a separate, less well-understood effect on cardiac tissue, which is why it was studied for heart failure.

What dosage has been studied in humans?

Published human dose-response studies exist, but this session could not directly retrieve the specific numeric doses used in each study from the primary sources; consult the cited studies directly (for example, PubMed IDs 7957536, 8954038, and 7962341) for exact figures.

What dosage commonly circulates online?

Vendor and forum sources widely describe roughly 100 to 200 micrograms per subcutaneous injection, one to three times daily. This figure is widely repeated but its original source could not be verified.

Why is Hexarelin associated with “desensitization”?

Community reports and some pharmacology discussions describe hexarelin’s GH-releasing effect weakening with continuous daily use faster than other GHRP-family peptides, which is why many community protocols suggest shorter cycles or breaks; this pattern has not been formally quantified in a dedicated long-term human trial.

Has Hexarelin been studied in humans?

Yes. It has real published human dose-response pharmacology data and reached Phase II clinical trials for growth hormone deficiency and congestive heart failure, though development was discontinued.

What side effects have been reported?

Dose-dependent increases in cortisol and prolactin have been documented in pharmacology research. Community reports add increased hunger and water retention. Long-term safety from unsupervised use has not been established.

Is Hexarelin approved for use?

No. It was never approved for any indication and is sold only as an unregulated research chemical.

What remains unknown about Hexarelin?

The exact doses used in its foundational human trials were not independently retrieved in this research pass, the cardiac mechanism remains incompletely characterized, and the safety of repeated, long-term, unsupervised self-administration has not been established.

Bottom line

Hexarelin is one of the more clinically studied peptides in the GHRP family, with real published human dose-response data and a genuine (if discontinued) Phase II clinical history for growth hormone deficiency and heart failure. It was never approved or marketed, and the dosing figures circulating in bodybuilding and peptide communities today are widely repeated but not traceable to the original clinical protocols. Its reported tendency toward rapid desensitization with continuous use is a recurring theme across both community reports and some pharmacology discussion, but has not been formally established through dedicated long-term trials.