GHRP-2

1 Identity

Synthetic C-terminally amidated hexapeptide containing one non-proteinogenic residue and three D-centers. The active moiety of a foreign-registered diagnostic medicine. and CAS 158861-67-7 for the free base.

Sequence

H-D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2, where 2-Nal is beta-(2-naphthyl)alanine, a non-proteinogenic residue. Six residues. Three centers are D — D-Ala1, D-2-Nal2 and D-Phe5 — and three are L: Ala3, Trp4 and Lys6. 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. It is not human growth hormone, contains no somatropin sequence and shares no residues with it. Supplied as a lyophilized salt: acetate is specified, and trifluoroacetate carried over from preparative RP-HPLC is the common alternative, identified and quantified per lot rather than assumed away.

Molecular formula

C45H55N9O6 (free base). Mono-trifluoroacetate C47H56F3N9O8. Dihydrochloride C45H57Cl2N9O6.

Average mass

817.992 Da for C45H55N9O6 on IUPAC 2021 abridged conventional atomic weights. On the older pre-2021 conventional set the same formula gives 817.97, and both figures appear in supplier literature for the same molecule — the difference is the atomic-weight table, not the article, and average mass is never the acceptance test. Mono-trifluoroacetate 932.02, published as FW 932.0 by one institutional catalog. Dihydrochloride 890.91.

Monoisotopic mass

817.4275 Da neutral. [M+H]+ 818.4348; [M+2H]2+ 409.7210; [M-H]- 816.4203. Mono-trifluoroacetate 931.4204 neutral. Dihydrochloride 889.3809 neutral.

Salt / variant note

(1) Free base C45H55N9O6, 817.99 / 817.4275, CAS 158861-67-7. (2) mono-trifluoroacetate C47H56F3N9O8, 932.02 / 931.4204 — the form one institutional catalog actually sold, published there as FW 932.0, so a quoted "932" is a salt mass and not a heavier peptide. (3) pralmorelin dihydrochloride, CAS 158827-34-0, C45H57Cl2N9O6, 890.91 / 889.3809 — the form on which the Japanese registration rests. (4) GHRP-2 free acid, des-amide, C45H54N8O7, 818.98 / 818.4115, +0.98 Da — the commonest specified impurity and the commonest quiet substitution, because a certificate reporting a nominal "818" cannot tell it from the amide. (5) Same-shelf family substitutions at the same sellers: GHRP-6 C46H56N12O6 873.03 / 872.4446 (+55.0), hexarelin C47H58N12O6 887.06 / 886.4602 (+69.1), ipamorelin C38H49N9O5 711.87 / 711.3857 (-106.1). (6) Deletion sequences off the sterically demanding 2-Nal coupling: des-Lys6 C39H43N7O5 689.82 / 689.3326, des-Ala1 C42H50N8O5 746.91 / 746.3904. (7) two substitutions no arithmetic can reach. Beta-(1-naphthyl)alanine is an exact constitutional isomer of the 2-naphthyl building block and gives an identical formula and an identical mass to every decimal place; and an all-L article, or one epimerized at any single one of the three D-centers, is exactly isobaric and co-elutes on an achiral reversed-phase column. Neither is visible to accurate mass and neither is visible to RP-HPLC area percent. (8) Tryptophan oxidation products at +16 and +32 Da, 833.99 and 849.99 average.

2 Class & testing panel

Form

Single article

Testing panel

P3 — panel definitionTwo things the panel has to reach on this article cannot be reached by mass at all. Three of the six centers are D, and an all-L article, or one epimerized at any single one of those three centers, is exactly isobaric with the specified article and co-elutes on an achiral reversed-phase column, so configuration has to be established by a method that discriminates configuration and is never inferred from accurate mass or from RP-HPLC area percent. And beta-(1-naphthyl)alanine is an exact constitutional isomer of the 2-naphthyl building block, identical in formula and identical in mass to every decimal place

3 Primary sources & evidence

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

Published literature exists. Human data exist for this molecule because it was developed and registered as a single-dose diagnostic agent, and the file is graded B for that indication only and B/C overall. Human diagnostic-validation studies, by identifier: Chihara K et al., Eur J Endocrinol 2007, PMID 17609397, DOI 10.1530/eje-07-0066, n=135, a single 100 microgram intravenous dose with two hours of sampling; Kinoshita et al., PMID 23079545, human comparative diagnostic study; Kageyama et al., PMID 18493103, human study; PMID 31776295, human observational study in non-functioning pituitary adenoma; Laferrere B et al., PMID 15699539, human study, n=7; Van den Berghe et al., PMID 12030918, human study in critical illness. Review: PMID 42395176 (2026), which states that GHRP-2 has an established clinical diagnostic role in Japan while broader therapeutic use remains limited and is not supported by widespread regulatory approval. Japanese clinical literature describes the GHRP-2 test alongside glucagon and arginine as recommended alternatives to the insulin tolerance test (PMID 23079545). Beyond that the file is predominantly in-vitro receptor pharmacology, GHS-R1a binding and signaling assays, and rodent work. Indicative volume for the citation index: of the order of 200 to 300 PubMed-indexed records, of which a small number are human interventional and nearly all of those are acute single-dose diagnostic-protocol studies from Japanese and European centers in the 1990s and 2000s. No long-term controlled human trial was identified and no registered therapeutic efficacy trial; the human dataset that exists is single-dose and does not extend to any other pattern of exposure.

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, protected from light in amber glass or foil overwrap — the tryptophan indole and the naphthalene ring make the solid photolabile. Hygroscopic as the acetate salt. Equilibrate the sealed container to ambient temperature before opening so that atmospheric moisture does not condense onto the cake. Reconstituted solution is aliquoted single-use and held at -80 degrees C; FDA's published concern for this substance is aggregation, so freeze-thaw cycling is prohibited on the label rather than merely discouraged. Ships ambient with a labeled cumulative excursion allowance and a single-use temperature logger in every export carton.

Shelf life

The interval is provisional at 24 months at -20 degrees C plus or minus 5 degrees C protected from light from the date of QA release, pending the company's own stability data. Interim pulls at 3, 6, 9 and 12 months real time plus 6 months accelerated at 40 degrees C and 75 percent relative humidity. Stability-indicating attributes: tryptophan-oxidation products at +16 and +32 Da, total related substances, the des-amide free acid, and aggregate content by SE-HPLC, the last of these because aggregation is the concern FDA published by name against this substance. Extension beyond 24 months only on long-term data from three commercial lots. Printed retest date on every vial, first-expiry-first-out enforced against that date.