Hexarelin

1 Identity

Synthetic C-terminally amidated hexapeptide with two D-centers, one of them a non-proteinogenic methylated tryptophan. Development codes trace to Mediolanum, Europeptides and later Ardana; development was discontinued and no marketing authorization exists anywhere. Not a synonym: GHRP-6 is the des-methyl analog, 14.02 Da lighter.

Sequence

H-His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2. Six residues. Two are D-configured — D-2-methyl-Trp2 and D-Phe5 — and the position-2 residue is additionally non-proteinogenic, carrying a methyl substituent at position 2 of the indole ring. His1, Ala3, Trp4 and Lys6 are L. Free N-terminal alpha-amine. The C-terminus is a primary carboxamide, not a free acid. No acetylation, no acylation, no lipidation, no PEGylation, no disulfide (there is no cysteine), no metal center, no glycosylation. Two indole side chains, one of them methylated, make the solid photolabile and oxidation-sensitive. Its two most consequential related substances are its position-2 epimer bearing L-2-methyl-Trp, and its des-methyl analog — which is GHRP-6, a separate record in this catalog, 14.02 Da lighter and far cheaper. Hexarelin therefore cannot be released on any method that does not resolve GHRP-6 from it, and the two are never run on the same fill line without a cleaning-verification swab reported to the lot record. Supplied as a lyophilized salt; acetate specified, trifluoroacetate the common alternative, identified and quantified per lot.

Molecular formula

C47H58N12O6 (free base). Mono-acetate C49H62N12O8. Mono-trifluoroacetate C49H59F3N12O8.

Average mass

887.059 Da for the free base C47H58N12O6 on IUPAC 2021 abridged conventional atomic weights; listings commonly print 887.06. On the older pre-2021 conventional set the same formula gives 887.04, and one institutional supplier's catalog prints FW 887.0 for the same article — one molecule, three tables, no disagreement. Mono-acetate 947.11; mono-trifluoroacetate 1001.08. One published figure is simply wrong and is set out here so it is not copied: an automated read of a public reference page returned 902.03 g/mol for this formula, which is arithmetically impossible for C47H58N12O6 and is exactly the kind of restated number this catalog refuses to carry.

Monoisotopic mass

886.4602 Da neutral. [M+H]+ 887.4675; [M+2H]2+ 444.2374; [M-H]- 885.4530. Mono-acetate 946.4814 neutral; mono-trifluoroacetate 1000.4531 neutral.

Salt / variant note

(1) Free base C47H58N12O6, 887.06 / 886.4602, CAS 140703-51-1. (2) GHRP-6, C46H56N12O6, 873.03 / 872.4446, exactly -14.016 Da — the des-methyl analog, a separate record in this catalog, cheaper, stocked far more widely, and the substitution to expect because the arithmetic is trivial and the commercial incentive runs this way. (3) Hexarelin free acid, des-amide, C47H57N11O7, 888.04 / 887.4442, +0.98 Da. (4) Mono-acetate C49H62N12O8, 947.11 / 946.4814; mono-trifluoroacetate C49H59F3N12O8, 1001.08 / 1000.4531; each further TFA adds 114.02 average and 113.993 monoisotopic. (5) Indole oxidation: mono-oxide C47H58N12O7 903.06 / 902.4551, di-oxide C47H58N12O8 919.06 / 918.4501. (6) Same-shelf family: GHRP-2 817.99 / 817.4275 (-69.1) and ipamorelin 711.87 / 711.3857 (-175.2). (7) two substitutions that survive every mass measurement ever made on this molecule. An article built from Fmoc-D-1-methyl-tryptophan — methylated on the indole nitrogen instead of at ring position 2 — has the identical formula C47H58N12O6 and an identical mass to every decimal place; and [L-2-methyl-Trp2]-hexarelin, the position-2 epimer, is likewise exactly isobaric and co-elutes on an achiral column. (8) A purity-grade variant that is genuinely two different articles at two institutional suppliers: one ships not less than 98 percent and the other not less than 90 percent by HPLC under the same name and the same CAS — an eight-point difference in specified purity that no arithmetic on the label will reveal.

2 Class & testing panel

Form

Single article

Testing panel

P3 — panel definition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

Published literature exists and consists of in vitro receptor pharmacology — GHS-R1a and, separately, CD36 — together with a substantial rodent literature spanning endocrine and cardiovascular model systems. Human data consist of small single-dose and short multiple-dose pharmacology studies from the 1990s, predominantly from Italian centers, typically 8 to 30 subjects. Clinical development was discontinued; there is no registration anywhere and no long-term controlled human trial was identified. Indicative volume for the citation index: roughly 200 to 300 PubMed-indexed records, the large majority preclinical, with human work concentrated in a fifteen-year window that closed around 2005. Two attribution rules travel with this article and are enforced on the citation index page. First, literature published under "GHRP-6" belongs to the des-methyl analog and is not evidence for this article; the two are different molecules and the catalog holds separate records for them. Second, historical importance in the discovery of the ghrelin system is a fact about the history of pharmacology and is routinely misread as clinical validation.

4 Storage & specification

Storage

White to off-white lyophilized powder in a screw-cap amber borosilicate vial with a PTFE-lined closure; a laboratory-chemical presentation, not a stoppered and crimped injection vial, with no sterility claim. Store at -20 degrees C plus or minus 5 degrees C, desiccated, tightly closed, in amber glass or foil overwrap — two indole side chains, one of them methylated, make the solid photolabile and oxidation-sensitive. Hygroscopic as the acetate salt. Equilibrate the sealed container to ambient temperature before opening so that atmospheric moisture does not condense onto the cake. Segregated from GHRP-6 at every point — separate shelf, separate weighing area, separate scoop, and no shared fill line without a cleaning-verification swab reported to the lot record — because the two differ by one methyl group and the commercial incentive runs toward substituting the cheaper article for this one. Reconstituted solution is aliquoted single-use and held at -80 degrees C; the imidazole makes the solution pH-sensitive, so the diluent and its pH are stated on the label rather than left to the user. Ships ambient with a labeled cumulative excursion allowance and a single-use temperature logger in every export carton.

Shelf life

Provisional 24 months at -20 degrees C plus or minus 5 degrees C protected from light, from the date of QA release, stated as provisional pending the company's own stability data. Stability-indicating attributes: the sum of indole-oxidation products at +16 and +32 Da, the position-2 epimer, the des-amide free acid, and total related substances. Real-time pulls at 3, 6, 9 and 12 months at the labeled condition plus 6 months accelerated at 40 degrees C and 75 percent relative humidity, with an ICH Q1B photostability challenge run once on the launch lot in the final container — on a molecule with two indoles that is a specification, not a formality. Extension beyond 24 months only on long-term data from three commercial lots. Printed retest date on every vial and first-expiry-first-out enforced against that date rather than against receipt date; material passing retest is re-dated for a further 12 months, material failing is destroyed and the destruction is recorded.