GHRP-6

1 Identity

Synthetic C-terminally amidated hexapeptide with two D-centers. All six residues constitutionally proteinogenic. The prototype of the growth hormone-releasing peptide series. because no CAS registry number appears in the PubChem synonym record for CID 4345065 while a CAS number is widely quoted in commercial listings. both recorded as commonly published values rather than as verified ones. SKF-110679 and His-D-Trp-Ala-Trp-D-Phe-Lys-NH2; CAS 87616-84-0 for the free base and 145177-42-0 for the acetate. Not synonyms: GHRP-2, hexarelin and ipamorelin are separate records with separate masses.

Sequence

H-His-D-Trp-Ala-Trp-D-Phe-Lys-NH2. Six residues. All six are constitutionally proteinogenic, but two are D-configured — D-Trp2 and D-Phe5 — while 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 make the solid photolabile and oxidation-sensitive; the imidazole of His1 makes the salt pH-sensitive on reconstitution. GHRP-6 is the des-methyl congener of hexarelin, a separate record in this catalog: the two differ only by a methyl group on the indole of the position-2 tryptophan, 14.02 Da. Each is therefore a named specified impurity risk in the other, and the two are never processed 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

C46H56N12O6 (free base). Tri-acetate C52H68N12O12. Mono-acetate C48H60N12O8.

Average mass

873.032 Da for C46H56N12O6 on IUPAC 2021 abridged conventional atomic weights. On the older pre-2021 conventional set the same formula gives 873.01; the difference is the atomic-weight table, not the article. Tri-acetate 1053.19, published as FW 1053.2 by one institutional catalog; mono-acetate 933.08. PubChem CID 4345065 gives MW 873.0, which is the same number.

Monoisotopic mass

872.4446 Da neutral. [M+H]+ 873.4519; [M+2H]2+ 437.2296; [M-H]- 871.4373. Tri-acetate 1052.5080 neutral.

Salt / variant note

(1) Free base C46H56N12O6, 873.03 / 872.4446, CAS 87616-84-0. (2) tri-acetate C52H68N12O12, 1053.19 / 1052.5080 — the institutional article is a TRIS-acetate, not a mono-acetate, published as FW 1053.2 under CAS 145177-42-0, which means the free-base content of that powder is about 82.9 percent w/w before any water is counted; a certificate reporting "purity 98 percent" on a tri-acetate without stating net peptide content is describing something other than milligrams of peptide. (3) Mono-acetate C48H60N12O8, 933.08 / 932.4657. (4) Trifluoroacetate adducts, +114.02 average / +113.993 monoisotopic each. (5) GHRP-6 free acid C46H55N11O7, 874.02 / 873.4286, +0.98 Da — the commonest specified impurity. (6) hexarelin C47H58N12O6, 887.06 / 886.4602, exactly +14.016 Da — the des-methyl relationship runs both ways, and the commercial substitution runs toward the more expensive molecule: GHRP-6 sold as hexarelin. (7) Indole oxidation products: mono-oxide C46H56N12O7 889.03 / 888.4395, di-oxide C46H56N12O8 905.03 / 904.4344. (8) [D-Lys3]-GHRP-6, C49H63N13O6, 930.13 / 929.5024 — a distinct cataloged analog, sold as the trifluoroacetate, sitting on the same shelf under a nearly identical name. (9) Same-shelf family: GHRP-2 817.99 / 817.4275 (-55.0) and ipamorelin 711.87 / 711.3857 (-161.2). (10) the invisible variant: [L-Trp2]-GHRP-6, the position-2 epimer, is exactly isobaric to every decimal place and co-elutes on an achiral reversed-phase column. No mass measurement of any accuracy and no achiral chromatography will ever see it.

2 Class & testing panel

Form

Single article

Testing panel

P3 — panel definitionIdentity is fully definable on that panel and the reference standards it requires are procurable, but one of them has to be made to order. [L-Trp2]-GHRP-6, the position-2 epimer of this article, is exactly isobaric with it to every decimal place and co-elutes on an achiral reversed-phase column, so a custom [L-Trp2] epimer reference standard is a requirement of release rather than a refinement of it, and no mass measurement and no achiral chromatography substitutes for it. Two centers are D, and the same holds for an epimer at either of them

3 Primary sources & evidence

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

Published literature exists. The file is graded D, and D/C overall, on the basis that genuine human pharmacology exists while no human efficacy trial for any therapeutic outcome does. Human studies, by identifier: Frieboes RM et al., 1995, PMID 7617137, human study whose measured variables included neuroendocrine and sleep-architecture parameters; follow-up PMID 10336729, human study on nocturnal secretion patterns; Bellone J et al., 1995, PMID 7581965, human study in children with short stature using an oral route; Cabrales A et al., Eur J Pharm Sci 2013, 48(1-2):40-46, PMID 23099431, DOI 10.1016/j.ejps.2012.10.006, human pharmacokinetic study, n=9. Family review: PMID 42395176 (2026). Beyond that the file is in-vitro receptor pharmacology — GHS-R1a binding and signaling, and separately CD36 binding — together with a large rodent literature and preclinical work in animal and cell models, much of the latter from Cuban research programs. Indicative volume for the citation index: several hundred PubMed-indexed records, overwhelmingly preclinical, with fewer than twenty human studies and none identified after approximately 2005. No modern controlled human trial, no registration in any jurisdiction, no long-term human safety dataset, no immunogenicity data and no carcinogenicity data were identified. Regulatory signal recorded as a fact about the regulator's document rather than about the molecule: FDA's Category 2 entry cites immunogenicity risk, a potential effect on cortisol, and decreased insulin sensitivity. Historical note for the citation index: GHRP-6 predates the identification of ghrelin and the deorphanization of GHSR-1a, and that historical importance is routinely misread as clinical validation — it made the molecule a useful pharmacological probe, not a validated therapy.

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. Offered in 100 mg and 500 mg vials. Store at -20 degrees C plus or minus 5 degrees C, desiccated, tightly closed. Amber glass or foil overwrap is mandatory rather than precautionary: two indole side chains make this the most photolabile of the four secretagogues in the catalog. Hygroscopic as the acetate salt, and markedly so as the tri-acetate. Equilibrate the sealed container to ambient temperature before opening. Segregated from hexarelin at every point — separate shelf, separate weighing area, 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 substitution runs toward the more expensive article. 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, total related substances, the des-amide free acid, and aggregate content by SE-HPLC, the last because FDA's published Category 2 concern for this substance is immunogenicity via aggregation. Interim 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 a photostability challenge under ICH Q1B run once on the launch lot in the final container. 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.