Growth Hormone
CAS
140703-51-1
Molecular Weight
887
Da
A synthetic hexapeptide that is a modified derivative of GHRP-6 in which tryptophan was substituted with the chemically more stable 2-methyl-tryptophan. Developed in the 1990s by Italian pharmaceutical company Europeptides. Plasma growth hormone concentrations increase dose-dependently after injection, peaking at about 30 minutes and decreasing to baseline within 240 minutes with a half-life of about 55 minutes. Distinct from other GH secretagogues in this catalog for two reasons, it is among the most potent GH releasers studied and it has a separate cardioprotective mechanism independent of GH release entirely. Research compound only with no regulatory approval.
Injectable
Intranasal Suitable
Uncertain
Research Compound
Community signal is sparse, Hexarelin has largely been displaced by Ipamorelin in practical use because of Ipamorelin's cleaner side effect profile. Reports that do exist note potent GH release but also cortisol and prolactin elevation, which the community treats as a meaningful drawback. Desensitization with repeated dosing is frequently flagged, leading experienced users to recommend short cycles or intermittent use. Cardiac function discussions appear occasionally in longevity-focused forums, referencing the animal cardioprotection data. The community consensus seems to be that Hexarelin is less preferable than alternatives unless specific GH potency is the priority.
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Hexarelin belongs to the growth hormone releasing peptide (GHRP) family, synthetic compounds designed to mimic ghrelin's GH-releasing activity with improved stability and potency. The key structural modification from its parent compound GHRP-6 is the methylation of tryptophan at the 2-position, which increases metabolic stability and receptor binding affinity. Hexarelin is an analog of growth hormone-releasing peptide 6 (GHRP-6) that potently stimulates growth hormone secretion in infant and adult rats. It was one of the first GHRPs to undergo human clinical trials, with early dose-finding studies establishing its pharmacokinetic profile. Development was ultimately discontinued for commercial reasons rather than safety concerns, leaving it in research compound status despite a reasonably well-characterized human evidence base relative to many compounds in the Growth Hormone category.
Hexarelin acts primarily through the growth hormone secretagogue receptor 1a (GHSR-1a), the ghrelin receptor, in the pituitary and hypothalamus. GHSR-1a activation triggers intracellular calcium release and PKC signaling that stimulates somatotroph cells to secrete GH in a pulsatile pattern. Three different mechanisms are postulated for Hexarelin stimulation of GH secretion: a direct action on the pituitary; an indirect action that involves release of GHRH; and an action through the release of a still unknown hypothalamic factor which elicits GH release acting synergistically.
What makes Hexarelin mechanistically distinct is its activity at CD36, a scavenger receptor expressed in cardiomyocytes, macrophages, and endothelial cells, that is entirely independent of GHSR-1a and GH secretion. Other studies reported that when GHSR-1a activation was identical, Hexarelin and ghrelin had similar cardiac effects, although the dosage of ghrelin was 10 times higher than that of hexarelin in molar terms, suggesting the CD36 pathway accounts for Hexarelin's disproportionate cardioprotective potency. This dual receptor activity is unique among the GH secretagogues in this catalog.
Hexarelin's primary studied application is growth hormone stimulation for body composition, recovery, and anti-aging, shared with Ipamorelin, CJC-1295, and Sermorelin in this catalog. Its advantage over Ipamorelin is greater raw potency; its disadvantage compared to CJC-1295/Ipamorelin combinations is the desensitization that occurs with chronic use, making cycling protocols necessary.
Cardiovascular protection is Hexarelin's most scientifically distinctive application. Studies show Hexarelin protects mouse cardiomyocytes from ischemia/reperfusion injury through regulation of intracellular calcium, and one dose of oral hexarelin protects chronic cardiac function after myocardial infarction. This cardioprotective activity through CD36 is observed even in growth hormone deficient models where GH release is absent, confirming it is mechanistically independent of the GH axis. Human cardiovascular data does not exist but the animal evidence base for cardiac applications is among the most robust for any GH secretagogue.
In the biohacking community Hexarelin is used primarily for GH optimization and body composition with the cardiac protection benefit considered a secondary advantage.
The most commonly noted concern is desensitization — unlike Ipamorelin which shows minimal tachyphylaxis, Hexarelin causes measurable reduction in GH response with continuous administration, necessitating cycling protocols. Hexarelin and GHRH are synergistic, a property which is lost after repeated administration. Cortisol and prolactin elevation have been reported at higher doses, a meaningful distinction from Ipamorelin's cleaner hormonal profile. Water retention and mild fatigue are commonly reported in community use. Not approved for human therapeutic use. Research compound only.
Available as a lyophilized sterile powder for reconstitution, typically supplied in vials of 2-5mg. Administered via subcutaneous injection. The short half-life of approximately 55 minutes makes dosing frequency an important consideration. Unlike Ipamorelin which is typically used daily, Hexarelin is more commonly used in shorter cycles given desensitization concerns. Research compound only.
No FDA or EMA approval for any indication. Development was discontinued commercially despite positive early human trial data. Not available through licensed compounding pharmacies. Research compound only. WADA prohibited under Section S2 as a GH releasing factor, relevant for competitive athletes.
https://pubmed.ncbi.nlm.nih.gov/7957536/
https://pubmed.ncbi.nlm.nih.gov/7910650/
https://pmc.ncbi.nlm.nih.gov/articles/PMC4178518/
https://pubmed.ncbi.nlm.nih.gov/24747279/
Ipamorelin, CJC-1295, Ibutamoren, Sermorelin
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