Quick answer: Hexarelin is a synthetic hexapeptide, His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2, derived from GHRP-6 and studied as a growth hormone secretagogue acting on the ghrelin receptor GHS-R1a. It is also reported to bind CD36, which sets it apart in the preclinical literature. It is a laboratory research compound only. This explainer covers the name, structure, research themes, how it differs from ipamorelin, and what to check on a certificate of analysis.
Where the name Hexarelin comes from
Hexarelin is a nonproprietary-style name, not a sequence code. The “hexa-” prefix reflects its length, six residues, and the “-relin” ending marks a compound studied for growth hormone (GH) release in assays. In catalogs it appears as “hexarelin,” “hexarelin acetate,” or occasionally by its older research designation, examorelin.
The sequence is His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2, with a molecular weight of roughly 887 g/mol. It was developed in the 1990s by Italian researchers as a modified analog of GHRP-6, an earlier synthetic hexapeptide. The key change is the D-2-methyltryptophan at position two, which makes the molecule more resistant to peptidases than its parent. Like other members of the family, the C-terminus is amidated. The chemistry is summarized in the Hexarelin research overview.
A growth hormone secretagogue, not a growth hormone
Hexarelin is not growth hormone and contains no part of its sequence. It belongs to the growth hormone secretagogue (GHS) class: compounds that act on the growth hormone secretagogue receptor 1a (GHS-R1a), the receptor later shown to be activated by the natural hormone ghrelin. Synthetic secretagogues were studied for years before ghrelin was identified in 1999, so the early literature describes a receptor with no known natural ligand.
What makes hexarelin a distinct topic from its relatives is a second binding site. Work published in the early 2000s reported that hexarelin and related peptides also bind CD36, a scavenger receptor found in heart and vascular tissue, and that this binding was separate from GHS-R1a. That finding opened a line of preclinical research on cardiac tissue models that does not apply to every secretagogue, and it is one reason hexarelin is often discussed on its own rather than as a copy of GHRP-6.
It also helps to keep the two receptor routes apart. GHS-R1a agonists such as hexarelin and ipamorelin act on the ghrelin receptor. GHRH analogs such as sermorelin and CJC-1295 act on the GHRH receptor. A direct comparison with its smaller cousin is in Hexarelin vs. Ipamorelin.
What the preclinical literature examines
Everything in this section is preclinical or mechanistic, drawn from cell, tissue and animal work. None of it is a statement about use in people, and nothing here describes a benefit.
Receptor pharmacology. Reviews of the secretagogue class describe how hexarelin and related peptides were characterized in pituitary cell cultures and in rodents, with dose-related GH release in those systems. These reviews are the best starting point for the history of the family.
The CD36 question. The cardiac-tissue literature reports a binding site for hexarelin on CD36 in heart membranes, distinct from GHS-R1a. Researchers have used this to ask whether some of the compound’s effects in isolated tissue and animal models are independent of GH release. The picture is still discussed, and primary papers should be read directly.
Desensitization. A recurring theme in the secretagogue literature is that the GH response to continued exposure can decline in experimental systems, a phenomenon called desensitization or tachyphylaxis. It is a design consideration for researchers who plan longer experiments and is one of the practical differences discussed between hexarelin and more selective compounds.
Other hormone axes. Compared with ipamorelin, hexarelin is generally described in the older literature as having a broader footprint on ACTH and cortisol readouts in the models tested. That is a laboratory observation, not a safety conclusion.
A caution on interpretation: much of the hexarelin literature is from the 1990s and early 2000s, parts of it come from a small number of groups, and online summaries often overstate it. Read the primary sources.
Hexarelin and related compounds at a glance
The table lists descriptors only. It does not rank compounds or imply performance.
| Compound | Class | Length | Receptor |
|---|---|---|---|
| Hexarelin | Ghrelin-receptor agonist (GHS) | 6 residues | GHS-R1a (also reported at CD36) |
| GHRP-6 | Ghrelin-receptor agonist (GHS) | 6 residues | GHS-R1a |
| Ipamorelin | Ghrelin-receptor agonist (GHS) | 5 residues | GHS-R1a |
| Sermorelin | GHRH analog | 29 residues | GHRH receptor |
| CJC-1295 | GHRH analog | 30 residues | GHRH receptor |
For the pentapeptide alternative, see the Ipamorelin explainer.
Handling the lyophilized powder
Hexarelin is supplied as a freeze-dried powder. The general rules for lyophilized peptides apply: keep sealed vials cold, dry and out of light, avoid repeated warming and cooling, and record the date a vial is first opened. Let a cold vial reach room temperature before the stopper is pierced so condensation does not form on the cake. The sequence contains two tryptophan residues, which are among the amino acids most sensitive to light and oxidation, so protection from light and from prolonged air exposure deserves a little extra attention.
A simple log (lot number, date opened, storage location) prevents most confusion. Broader supplier-side considerations are in the guide to choosing a peptide supplier.
What to check on a Hexarelin certificate of analysis
A modified hexapeptide with two tryptophans and unnatural residues can accumulate oxidized or deletion by-products, so documentation matters more than a headline percentage.
HPLC purity with the chromatogram. Look for the full trace and see whether minor peaks are integrated. Understanding HPLC purity explains the numbers.
Identity confirmation. As general buying guidance, ask which method confirms a molecular weight near 887 g/mol and read it in the report. A method that only repeats the HPLC retention time tells you less than one that reads mass directly.
Lot reference and date that match the vial in your hands, plus the name of the testing laboratory.
Fill amount and whether it describes total powder or net peptide content.
Walk through each section with how to read a COA and Hexarelin purity testing. For sourcing questions see where to buy Hexarelin, and for our listing see the Hexarelin product page. Published certificates are on the COA page.
Common misunderstandings
“Hexarelin is growth hormone.” It is a small synthetic peptide that acts on receptors and contains no part of the GH sequence.
“Hexarelin is the same as GHRP-6.” It is a modified analog with a different residue at position two and a separately reported CD36 interaction.
“Older means better characterized.” The literature is older, not necessarily larger or independently replicated.
“Animal data predicts human outcomes.” It does not, and this article makes no such claim.
Frequently asked questions
What is Hexarelin?
A synthetic hexapeptide, His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2, derived from GHRP-6 and studied as a growth hormone secretagogue acting on GHS-R1a.
What does the name Hexarelin mean?
“Hexa-” refers to its six residues and “-relin” marks compounds studied for growth hormone release. It is not a sequence code.
What is Hexarelin’s molecular weight?
Roughly 887 g/mol.
Is Hexarelin the same as growth hormone?
No. It is a small peptide that acts on receptors and contains no part of the growth hormone sequence.
How is Hexarelin different from GHRP-6?
It is a modified analog with D-2-methyltryptophan at position two, which makes it more resistant to peptidases, and it has a separately reported CD36 binding site.
What is the CD36 finding?
Early-2000s work reported that hexarelin binds CD36 in heart membranes, separate from GHS-R1a, which led to preclinical cardiac tissue research.
Is Hexarelin approved in the United States?
No. V8 Peptides sells it for laboratory research use only, not for human or animal consumption.
What kind of studies mention Hexarelin?
Pituitary cell culture, rodent pharmacology, receptor-binding work and cardiac tissue models. All preclinical.
What should I look for on a Hexarelin COA?
An HPLC chromatogram, an identity method that confirms the expected mass, a lot reference matching your vial, a test date and a named laboratory.
How is lyophilized Hexarelin stored?
Sealed, cold, dry and protected from light, with temperature cycling avoided and the opening date recorded.
All V8 Peptides products are sold for laboratory research use only. They are not drugs, foods, or cosmetics and are not intended for human or animal consumption.
References
- Smith RG, et al. Peptidomimetic regulation of growth hormone secretion. Endocrine Reviews. 1997;18(5):621-645.
- Bodart V, et al. Identification and characterization of a new growth hormone-releasing peptide receptor in the heart. Circulation Research. 2002;90(8):844-849.
- Kojima M, et al. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature. 1999;402:656-660.