Description
PrymaLab · Research Use Only
Hexarelin Peptide 5mg
Two receptors · which is one more than the rest of the class
Hexarelin peptide has a property no other compound in this class shares. It binds a second receptor, CD36, which sits outside the pituitary entirely, and that means a hexarelin experiment can produce effects that have nothing to do with growth hormone at all.
Specification Table
| Property | Value |
|---|---|
| Compound | Hexarelin |
| Alternative name | Examorelin |
| Class | Growth hormone releasing peptide, hexapeptide |
| Residue count | 6 |
| Molecular weight, calculated | Approximately 887.0 g/mol for the free base |
| Molecular formula | C47H58N12O6 |
| CAS | 140703-51-1 |
| Primary receptor | GHS-R1a |
| Second receptor | CD36, a scavenger receptor expressed in cardiac tissue and elsewhere |
| Structural relationship to GHRP-6 | One added methyl group on the position 2 tryptophan |
| Carboxy terminus | Amidated |
| Development status | Reached phase II clinical evaluation and was never marketed in any jurisdiction |
| Appearance | White lyophilized powder |
| Purity | Per lot-specific certificate of analysis |
| Storage, lyophilized | 2-8°C short term, -20°C for extended storage, protected from light and moisture |
What Second Receptor Does Hexarelin Peptide Bind?
CD36 is a scavenger receptor, and its presence in this story was not predicted by anyone designing growth hormone secretagogues.
Its ordinary business is binding modified lipoproteins, long-chain fatty acids and thrombospondin. It is expressed in cardiac tissue, in macrophages and in adipocytes, and it has nothing to do with the pituitary.
Published work in the early 2000s established that hexarelin peptide binds it, and that binding accounts for cardiac effects observed in preparations where growth hormone release could not explain them.
That is the finding that matters. The reason it matters is methodological rather than pharmacological, and it changes how any experiment using this compound has to be built.
Every other secretagogue in this catalogue produces its effects through one receptor. An experiment using one of them can attribute an observation to that pathway with reasonable confidence.
An experiment using hexarelin peptide cannot, because two pathways are open and the compound is engaging both.
Attributing a hexarelin result to growth hormone signalling therefore requires either a system that does not express CD36 or a control that blocks it, and neither is a small addition to a study design.
That is a genuine cost, and it is also the reason the compound exists as a distinct research tool rather than as a slightly different version of GHRP-6.
What Did One Methyl Group Change?
Hexarelin peptide differs from GHRP-6 by a single methyl group on the position 2 residue, which is about as small a structural edit as medicinal chemistry produces.
The parent compound carries a D-tryptophan there. This one carries a 2-methyl-D-tryptophan, so the indole ring gains one carbon and three hydrogens.
Fourteen daltons on an 873 dalton molecule is under two percent of the mass and it changed the pharmacology more than that proportion suggests.
Potency at the pituitary rose. The methyl group sits on a ring that occupies a hydrophobic pocket. Adding bulk there improved the fit.
Resistance to degradation rose as well, because the substituted indole is a poorer substrate for the enzymes that would otherwise attack it.
The CD36 affinity came with the edit rather than being designed in, which is the usual way second targets are discovered.
For a certificate this has one direct consequence. The mass difference between hexarelin and GHRP-6 is fourteen daltons, so a mass check distinguishes them only if the instrument was set up to resolve that gap and someone compared against the right calculated figure.
A supplier quoting 873 rather than 887 has either shipped the wrong compound or calculated against the wrong sequence. Both are worth catching early.
One caution about how that comparison is usually drawn. Potency figures for the two compounds come from different studies in different preparations more often than from a single head-to-head experiment.
Where a ratio is quoted without naming the system it was measured in, it is a summary of the literature rather than a measurement.
Why Did It Stop at Phase II?
Hexarelin peptide reached phase II clinical evaluation and was never marketed anywhere, and the reason that is worth stating is what it implies about the available evidence.
A compound that stops at phase II usually has a published record from phase I and phase II work, which is considerably better than the record behind most compounds in this catalogue.
Human data on secretion responses exists. Data on longer exposure does not, because the studies that would have generated it were never run.
That asymmetry is the useful thing to carry into a study design. Short-exposure findings in the published record are real measurements taken under stated conditions. Anything about sustained exposure is extrapolation.
Development stopping is not by itself evidence of a problem. Programmes end for commercial reasons, for portfolio reasons, and because a sponsor changes hands, at least as often as they end for scientific ones.
What can be said accurately is that no regulator anywhere completed a review of this compound and that no approved formulation exists.
Anyone citing the phase II work should read it rather than a summary of it, because the endpoints those studies measured are narrower than the way they are usually described.
The same caution applies to the CD36 literature. It is small, specific, and frequently overstated once it has passed through a secondary source or two.
What Should a Hexarelin Certificate Show?
Seven fields, and two of them exist because of how close this molecule is to its parent.
The full construct written out, with the position 2 residue identified as 2-methyl-D-tryptophan rather than as tryptophan. That single specification distinguishes the article from GHRP-6.
Observed mass set against the calculated figure, with that figure printed rather than implied. Roughly 887 identifies this compound and roughly 873 identifies its parent.
Purity by reverse-phase HPLC with the chromatogram supplied, since deletion sequences and oxidised species both elute near the main peak and a percentage hides them.
Whether the carboxy terminus is amidated, which changes both mass and receptor activity and is a routine synthesis failure.
Counterion identity alongside net peptide content. A basic lysine on an 887 dalton backbone carries a trifluoroacetate share that commonly reaches twenty percent.
Lot number and synthesis date.
Whether light was excluded through packing and storage, because this sequence carries two indole rings and both are photosensitive.
A certificate that identifies the methylated residue explicitly is doing something most do not, and it is the field worth asking for if it is missing.
How Should a CD36 Control Be Designed?
A compound with two targets needs an experiment that can tell them apart, and there are three practical ways to build one.
The first is choosing a system that does not express CD36. Expression varies substantially between cell lines and tissues, so a preparation can be selected rather than corrected.
That has to be verified rather than assumed. Expression data for a given line in the published record may not match what the line in a particular freezer is doing.
The second is blocking. Antibodies against CD36 are available and well characterised, and running the experiment with and without one separates the contributions directly.
The third is parallel comparison. Run hexarelin peptide alongside a compound that binds GHS-R1a and not CD36, at concentrations giving matched receptor occupancy.
Anything the selective compound reproduces is a GHS-R1a effect. Anything it does not is a candidate for the second pathway.
That third approach is the cheapest of the three and the weakest, because matched occupancy is an assumption rather than a measurement in most systems.
It is still considerably better than the usual alternative, which is running hexarelin peptide alone and attributing whatever appears to growth hormone signalling.
The choice between the three depends on what is already available in the laboratory rather than on any of them being correct in the abstract.
What is not defensible is skipping the question, because a two-receptor compound in a one-receptor analysis produces a confident answer to a question nobody asked.
How Should the Vial Be Handled?
Handling matches the rest of the short secretagogues, with the light requirement carrying more weight than usual.
Sealed lyophilized powder is stable at 2 to 8 degrees Celsius for short periods and at minus 20 for extended storage, kept dark throughout.
Allow the vial to reach ambient temperature before the seal is broken, because the powder takes up atmospheric moisture readily and cold glass accelerates it.
Add diluent down the vial wall and swirl. Shaking drives peptide to the air-liquid interface, which is where aggregation begins.
Aliquot immediately on first reconstitution rather than at the end of a session, since material that has already sat at ambient temperature is the material most likely to be kept.
Keep solutions dark. The two indole rings oxidise faster in solution than in the dry state, and an illuminated bench is the realistic route to a degraded preparation.
Use low-binding consumables at working dilutions, since adsorption removes a measurable fraction into ordinary plastics.
Record lot, net peptide content, diluent volume and date. A hexarelin preparation carries an extra field worth noting alongside those four, which is whether the system under study expresses CD36.
A closing note on why the CD36 question belongs in the storage record at all.
Anyone repeating this work later, in a different preparation, needs to know which receptors were available in the system the original result came from.
Recording the cell line or tissue alongside the material details makes that reconstruction possible, and omitting it makes a hexarelin result difficult to interpret even by the laboratory that generated it.
That is a two-word entry in a notebook. It is also the difference between a result somebody can build on and one that has to be repeated from scratch.
Published Literature
Selected references on the second receptor, on human evaluation of this compound and on the receptor family.
- Bodart V, Febbraio M, Demers A, McNicoll N, Pohankova P, Perreault A, et al. Circulation Research. 2002;90(8):844-849. DOI: 10.1161/01.RES.0000016164.02525.B4
- Demers A, McNicoll N, Febbraio M, Servant M, Marleau S, Silverstein R, et al. Biochemical Journal. 2004;382(Pt 2):417-424. DOI: 10.1042/BJ20040036
- Imbimbo BP, Mant T, Edwards M, Amin D, Dalton N, Boutignon F, et al. European Journal of Clinical Pharmacology. 1994;46(5):421-425. DOI: 10.1007/BF00191904
- Howard AD, Feighner SD, Cully DF, Arena JP, Liberator PA, Rosenblum CI, et al. Science. 1996;273(5277):974-977. DOI: 10.1126/science.273.5277.974
Frequently Asked Questions
What is hexarelin peptide?
A six-residue synthetic growth hormone releasing peptide, also called examorelin, calculated at approximately 887 daltons for the free base and carrying CAS 140703-51-1.
What makes it different from the other secretagogues?
It binds two receptors rather than one. Alongside GHS-R1a it binds CD36, a scavenger receptor expressed in cardiac tissue, in macrophages and in adipocytes.
What is CD36 normally doing?
Binding modified lipoproteins, long-chain fatty acids and thrombospondin. It has no role in the pituitary, which is why its involvement here was not predicted.
Why does the second receptor matter experimentally?
Because two pathways are open at once. An observation cannot be attributed to growth hormone signalling without either a system that does not express CD36 or a control that blocks it.
How does it differ structurally from GHRP-6?
By one methyl group on the position 2 residue. The parent carries D-tryptophan, this carries 2-methyl-D-tryptophan, a difference of fourteen daltons.
What did that edit change?
Potency at the pituitary rose because the added bulk improved the fit in a hydrophobic pocket, and resistance to degradation rose because the substituted indole is a poorer enzyme substrate.
Was the CD36 affinity designed in?
No. It came with the edit and was found afterwards, which is the usual way second targets are discovered rather than planned.
How do I tell the two compounds apart on a certificate?
By mass and by sequence. Roughly 887 daltons is hexarelin, roughly 873 is GHRP-6, and the position 2 residue should be written as 2-methyl-D-tryptophan explicitly.
Did it reach clinical evaluation?
Yes, phase II, and it was never marketed in any jurisdiction. That means published human data exists for short exposure and does not exist for sustained exposure.
Does stopping at phase II mean something went wrong?
Not by itself. Programmes end for commercial and portfolio reasons at least as often as scientific ones. What can be said is that no regulator completed a review and no approved formulation exists.
Why does light exclusion matter here?
The sequence carries two indole rings and both are photosensitive. Oxidation proceeds faster in solution than in the dry state, so working dilutions need protection as much as the vial does.
What extra field should a hexarelin record carry?
Whether the system under study expresses CD36. That single fact determines whether a result can be attributed to the pituitary pathway at all.
Compliance Statement
Hexarelin peptide is sold exclusively for laboratory research use. It is not a drug, food, or cosmetic product, and it is not a dietary product of any kind. It is not approved by the FDA or any comparable authority for human or veterinary use, it reached phase II clinical evaluation and was never marketed in any jurisdiction so no regulator has completed a review of it, published human data covers short exposure only, and no compound in this range is offered for any human or veterinary purpose. This product is not intended to diagnose, treat, cure, or prevent any disease. It must not be given to humans or animals. Purchase is restricted to qualified researchers and institutions operating within applicable laws. All handling is the responsibility of the purchasing laboratory.
Other formats of Hexarelin
Hexarelin is also stocked as Hexarelin 5mg Nasal Spray and Hexarelin 2mg. Each listing states its own quantity and concentration, and the pen and vial comparison explains what changes between formats.
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