Hexarelin Acetate 5mg (with Bacteriostatic Water)

Hexarelin (sometimes written Examorelin in older literature) is a synthetic growth-hormone-releasing hexapeptide developed in the 1990s as part of a structured medicinal-chemistry effort to optimize the original growth-hormone-releasing peptide GHRP-6 for improved potency. The molecule is a six-amino-acid sequence — His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH₂ — that, despite its small size, is one of the more potent compounds in the GHRP (growth-hormone-releasing-peptide) class characterized in the published endocrine-research literature.

The interest in Hexarelin has run on two parallel tracks. The first track is endocrine research on growth-hormone secretion: like the other GHRPs and like the later peptidomimetic ghrelin-receptor agonists, Hexarelin stimulates pituitary growth-hormone release in research models, and it was characterized extensively in clinical-research studies in the 1990s as part of an evaluation of its potential as a growth-hormone secretagogue. The second track is cardiovascular research: characterizations of Hexarelin's effects in heart-tissue models led to a substantial research conversation about non-pituitary actions of GHRP-class compounds, with proposed cardioprotective effects mediated through CD36 and other receptors distinct from the canonical ghrelin receptor.

This page is an educational reference for readers who want to understand what Hexarelin is, where it sits in the broader GHRP family, what the published research describes about its mechanism and effects in laboratory and clinical-research settings, and how it compares to the related compounds in its class. It is not a medical guide, does not describe any therapy or personal-use protocol, and makes no claims about effects in people who acquire the compound for research purposes. Hexarelin supplied as a research peptide is intended for laboratory and analytical work only.

Hexarelin is a synthetic linear hexapeptide with the sequence His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH₂ and a molecular mass of approximately 887 daltons in the free-base form (the commercial acetate salt adds the counterion mass). The peptide incorporates several deliberate design modifications relative to a canonical L-amino-acid sequence: D-amino acids at positions 2 and 5 (the D-2-methyl-tryptophan and D-phenylalanine residues), a C-terminal amide rather than the standard free carboxylate, and the unusual D-2-methyl-tryptophan residue that gives the molecule much of its characteristic potency in receptor-binding assays. These modifications collectively give Hexarelin a substantially improved metabolic stability and binding affinity profile relative to the earlier prototype GHRP-6, while keeping the molecule as a six-amino-acid peptide compatible with standard synthesis approaches.

The compound was developed within the broader research program that characterized the GHRP class — a series of small synthetic peptides initially identified by Cyril Bowers and colleagues in the late 1970s and 1980s as compounds that stimulated growth-hormone release through what was then a mechanism distinct from the recently characterized growth-hormone-releasing hormone (GHRH). Bowers' GHRP-6 prototype provided the conceptual basis, and the subsequent optimization work — with contributions from multiple medicinal-chemistry groups — produced Hexarelin as one of the most potent and well-characterized members of the family.

The discovery of the natural ghrelin peptide in 1999 by Kojima and colleagues, and the subsequent identification of the ghrelin receptor (GHS-R1a) as the molecular target of the GHRP class, retrospectively resolved the mechanistic mystery of how compounds like Hexarelin worked. Hexarelin is a potent agonist of the GHS-R1a receptor — the same receptor naturally activated by ghrelin — and stimulates downstream growth-hormone release from the pituitary through that pathway. Subsequent characterization of additional non-GHS-R1a binding sites for Hexarelin — including CD36, a scavenger receptor expressed in heart and other tissues — has supported the proposed non-pituitary effects of the compound and contributed to the cardiovascular-research conversation that has developed around it.

It is worth being specific about what Hexarelin is not. It is not a GHRH analog; it operates through the GHS-R1a/ghrelin-receptor pathway rather than through the GHRH receptor that Sermorelin and CJC-1295 target. It is not natural ghrelin, which is a 28-amino-acid acylated peptide with much broader biology including substantial appetite and metabolic effects; Hexarelin is a small synthetic peptide that retains the growth-hormone-stimulating activity of the larger natural ligand while exhibiting a distinct profile of secondary effects. And it is not an approved medicine — despite substantial clinical-research evaluation in the 1990s and 2000s, it was not advanced through to regulatory approval as a growth-hormone secretagogue in any major jurisdiction.

Hexarelin's history is part of the broader story of the GHRP class. The story begins with Cyril Bowers and colleagues at Tulane University in the late 1970s. Bowers' group was conducting structure-activity work on opioid peptides when they noticed that certain peptide modifications produced compounds that, instead of opioid-like activity, stimulated growth-hormone release from cultured pituitary cells. The original active prototype, GHRP-6, was characterized in the early 1980s and provided the conceptual foundation for the entire GHRP class. The mechanism through which GHRP-6 worked was not initially clear; the compound stimulated growth-hormone release but did not bind to the GHRH receptor, suggesting an entirely separate signaling pathway that had not yet been molecularly identified.

Through the 1980s and 1990s, multiple medicinal-chemistry groups built on the GHRP-6 scaffold to develop more potent and metabolically stable analogs. The work at the Italian pharmaceutical company Mediolanum produced Hexarelin in the early 1990s as one of the most potent members of the family characterized to that point. The compound entered substantial clinical-research evaluation through the 1990s, with characterization across endocrine, pediatric-growth, and cardiovascular contexts. The published clinical-research literature on Hexarelin from this period is unusually substantive for a research peptide and includes work on its growth-hormone-stimulating effects in healthy subjects and in various clinical-research populations.

The 1999 discovery of natural ghrelin by Masayasu Kojima and colleagues at the Kurume University School of Medicine resolved the long-standing mechanistic mystery of the GHRP class. Kojima's group identified the natural ligand of the previously orphan GHS-R receptor and named it ghrelin (from a proto-Indo-European root meaning "to grow"). The identification confirmed that Hexarelin and the other GHRPs were operating through the ghrelin-receptor pathway, providing the molecular framework that the structure-activity work of the previous two decades had been implicitly building toward.

Through the 2000s, additional characterization of Hexarelin focused on its non-pituitary effects, particularly in cardiovascular research. The identification of CD36 as a binding site for Hexarelin in heart tissue, and the characterization of proposed cardioprotective effects in ischemia-reperfusion and other heart-stress research models, expanded the research conversation around the compound beyond its original endocrine framing. Despite the substantive clinical-research history and the interesting cardiovascular-research findings, Hexarelin was not advanced through to regulatory approval as a medicine, and the compound has remained in the research-peptide and academic-research space rather than the approved-pharmaceutical space.

Important milestones include Bowers' original GHRP-6 work in the late 1970s and early 1980s, the development of Hexarelin at Mediolanum in the early 1990s, the substantial 1990s clinical-research evaluation of the compound, the 1999 Kojima identification of ghrelin and the resolution of the GHRP-receptor question, and the subsequent 2000s characterization of CD36-mediated cardiovascular effects.

The science of Hexarelin is anchored in three connected areas: the ghrelin-receptor pharmacology that mediates its growth-hormone-stimulating effects, the structural design that gives it its potency and stability, and the non-pituitary effects characterized in cardiovascular and other research contexts.

• Hexarelin is a synthetic six-amino-acid growth-hormone-releasing peptide with the sequence His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH₂.
• It is a potent agonist of the ghrelin receptor (GHS-R1a) and stimulates pulsatile pituitary growth-hormone release in research models.
• Developed in the early 1990s as part of the broader GHRP-family optimization program initiated by Bowers' GHRP-6.
• Substantial 1990s-2000s clinical-research literature characterized its endocrine effects in healthy subjects and in various clinical-research populations.
• Distinctive cardiovascular-research conversation centers on CD36-mediated non-pituitary effects characterized in heart-tissue models.

Structurally, Hexarelin is a linear hexapeptide with the sequence His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH₂ and a molecular mass of approximately 887 daltons in the free-base form. The commercial acetate salt — the form supplied for research use — adds the acetate counterion mass (one or more equivalents depending on the lysine and histidine basic side chains).

The histidine at position 1 provides the N-terminal anchor and contributes the imidazole side chain that interacts with the GHS-R1a binding pocket. Position 2 is the D-2-methyl-tryptophan, the most unusual residue in the sequence and the one most responsible for the molecule's distinctive potency — the methyl group at the 2-position of the tryptophan indole and the D-configuration both contribute to optimized receptor contact. Position 3 is an L-alanine, a small spacer residue. Position 4 is an L-tryptophan, contributing additional hydrophobic and aromatic interactions with the receptor. Position 5 is a D-phenylalanine, contributing further receptor binding affinity and metabolic stability. Position 6 is L-lysine with a C-terminal amide cap, providing the basic C-terminal residue and the amide-modification stability.

The combination of D-amino acid substitutions, the unusual D-2-methyl-tryptophan, and the C-terminal amide collectively give Hexarelin a substantially improved binding affinity and metabolic stability profile relative to the GHRP-6 prototype, which has the sequence His-D-Trp-Ala-Trp-D-Phe-Lys-NH₂ without the 2-methyl modification on the tryptophan at position 2.

Hexarelin is studied in laboratory and clinical-research contexts that span endocrinology, cardiovascular research, and broader characterization of ghrelin-receptor pharmacology.

In endocrine research on the somatotropic axis, Hexarelin has been used extensively as a research tool to characterize growth-hormone-secretory dynamics, pituitary somatotrope responsiveness, and the interaction of GHRP-family compounds with simultaneously administered GHRH analogs. The strong and reproducible growth-hormone release induced by Hexarelin makes it a useful pharmacological tool for these endocrine-research applications. Comparative pharmacology studies have used Hexarelin alongside other GHRPs (GHRP-6, GHRP-2, Ipamorelin) and alongside the later peptidomimetic ghrelin-receptor agonists to characterize structure-activity relationships across the broader ghrelin-receptor agonist landscape.

In pediatric-endocrinology research, the 1990s and 2000s clinical-research literature characterized Hexarelin's growth-hormone-releasing effects in children with various growth disorders, contributing to the broader characterization of the somatotropic axis in those populations.

In cardiovascular research, Hexarelin has been used in heart-tissue cell culture, isolated-heart preparations, and animal models of cardiac ischemia and ischemia-reperfusion injury to characterize the proposed CD36-mediated cardioprotective effects. The cardiovascular-research literature distinguishes Hexarelin from some other GHRP-class compounds whose research focus has remained more narrowly on the endocrine axis.

In broader ghrelin-receptor pharmacology research, Hexarelin serves as a high-potency reference agonist for GHS-R1a in receptor-binding assays, in functional cellular assays measuring downstream signaling, and in comparative studies with other ghrelin-receptor ligands. The well-characterized binding profile and the high potency make Hexarelin a useful tool in the research-pharmacology context.

Across all of these contexts, the research applications are laboratory and analytical in nature in the research-peptide supply context. Some of the historical Hexarelin research was conducted in human clinical-research settings under institutional and regulatory oversight; the research peptide supplied for laboratory use does not include any clinical-research context and is intended for laboratory and analytical work only.

Hexarelin sits within the broader landscape of growth-hormone-secretagogue research compounds, with related but distinguishable comparators across the GHRP family, the GHRH-analog family, and the later peptidomimetic ghrelin-receptor agonists.

Hexarelin is a synthetic growth-hormone-releasing hexapeptide developed in the early 1990s as an optimized member of the GHRP family initiated by Bowers' GHRP-6. It is a potent agonist of the ghrelin receptor (GHS-R1a) and stimulates pulsatile pituitary growth-hormone release in research models. The structural design — particularly the unusual D-2-methyl-tryptophan at position 2 and the D-phenylalanine at position 5 — gives the molecule a binding affinity and metabolic stability profile that distinguishes it as one of the most potent members of its class.

The published research footprint of Hexarelin is substantial and spans two parallel research conversations. The first is the endocrine-research literature on growth-hormone secretion, with clinical-research characterization of its effects in healthy adults and in various clinical-research populations through the 1990s and 2000s. The second is the cardiovascular-research literature on proposed non-pituitary effects mediated through the CD36 scavenger receptor, with characterization in heart-tissue models including ischemia-reperfusion injury studies. The two research tracks together give Hexarelin one of the broader research profiles among the GHRP-class compounds.

The 1999 identification of natural ghrelin by Kojima and colleagues retrospectively resolved the long-standing mechanistic question of how Hexarelin and the broader GHRP class operate, providing the molecular framework — the GHS-R1a receptor — that the structure-activity work of the previous two decades had been implicitly building toward.

Hexarelin was not advanced through to regulatory approval as a medicine in any major international jurisdiction despite its substantive clinical-research history. It remains in the research-peptide and academic-research space and is supplied as a research peptide for laboratory and analytical use only. As a peptide-hormone-class compound, Hexarelin is prohibited under the WADA prohibited list in and out of competition, and that regulatory status is part of the relevant context for any educational discussion of the compound.

For students, researchers, and curious readers approaching Hexarelin for the first time, the most accurate framing is of a well-characterized synthetic ghrelin-receptor agonist with a substantial endocrine-research literature, a distinctive cardiovascular-research conversation, and a clear place in the broader story of GHRP-class compound development and the eventual identification of the natural ghrelin/GHS-R1a system.