Ipamorelin: A Research Monograph on the GHS-R1a Pentapeptide

Ghrelin made the shortlist for strangest hormone in endocrinology - an orexigenic signal secreted by the stomach, which is not where most researchers go looking for growth-hormone regulators. Ipamorelin (PubChem CID 9831659, CAS 170851-70-4) is a synthetic pentapeptide built to engage the receptor that ghrelin activates: the growth-hormone-secretagogue receptor type 1a (GHS-R1a), a Gq/11-coupled GPCR that sits at the intersection of appetite and the somatotropic axis. Five residues, C-terminally amidated, supplied strictly as a research reagent. Everything below describes what published studies have investigated, not any human use.

Key facts

What exactly is ipamorelin, and is the vial real?

Ipamorelin resolves in PubChem to CID 9831659, with molecular formula C38H49N9O5, molecular weight 711.9, and InChIKey NEHWBYHLYZGBNO-BVEPWEIPSA-N. CAS 170851-70-4 is among its synonyms. A name lookup returns CID 9831659; an independent reverse lookup of CAS 170851-70-4 against PubChem resolves to the same record with no divergent CID. The IUPAC name decomposes cleanly to the pentapeptide sequence: 2-amino-2-methylpropanoyl is Aib (alpha-aminoisobutyryl); imidazolyl-propanoyl is His; naphthalen-2-yl-propanoyl is D-2-Nal; phenylpropanoyl is D-Phe; and the C-terminal hexanamide is Lys-NH2, with (2R) stereocentres encoding the D-residues. CAS, CID and formula all point to a single molecule.

One mass figure worth noting: 711.9 is PubChem's average molecular weight; the monoisotopic value is 711.39. Some vendor data sheets quote 711.86 or 711.9 without stating the basis, which is the kind of ambiguity that makes a certificate of analysis the better document to cite. Always confirm the figure against the supplied lot CoA and state the basis when quoting a mass.

How is ipamorelin thought to work?

Ipamorelin is a peptidic agonist at the ghrelin / growth-hormone-secretagogue receptor type 1a (GHS-R1a), the Gq/11-coupled GPCR characterised in the foundational report by Raun K et al. (Eur J Endocrinol, 1998; PMID 9849822). That paper defined the pentapeptide structure and placed ipamorelin in the same receptor pharmacology group as the endogenous ligand ghrelin and other GHS-R1a agonists.

The receptor class distinction matters for catalogue grouping. GHS-R1a agonists act at a mechanistically separate target from growth-hormone- releasing-hormone (GHRH) analogues, which engage the GHRH receptor. Both sit somewhere on the broader growth-hormone axis, but shared-axis membership does not imply a shared receptor, and the two classes are not interchangeable at the bench. This page characterises receptor target and documented signalling coupling only; no downstream physiological effect, secretory output or body-composition consequence is asserted or implied.

What has the research actually looked at?

Two sources are catalogued here, characterised strictly by design and endpoint name. No result, magnitude, direction of change or benefit is reported or implied by any entry below.

Foundational characterisation. Raun K, Hansen BS, Johansen NL, et al. (Eur J Endocrinol, 1998; PMID 9849822) is the primary report that introduced ipamorelin and defined its pentapeptide structure (Aib-His-D-2Nal-D-Phe-Lys-NH2). Design: in-vitro receptor and secretory characterisation in pituitary cell preparations combined with preclinical in-vivo animal pharmacology. Pre-specified endpoints named (design descriptors only): in-vitro GHS-receptor agonist potency and efficacy; in-vivo plasma growth hormone concentration; plasma ACTH and cortisol concentrations as comparator hormonal endpoints. No outcome, magnitude or effect from this study is stated or implied here.

Interventional randomised trial. Beck DE et al. (Int J Colorectal Dis, 2014; DOI 10.1007/s00384-014-2030-8; ClinicalTrials.gov NCT00672074) conducted a prospective, multicentre, double-blind, randomised, placebo-controlled trial of intravenous ipamorelin versus placebo in a parallel-group design. The pre-specified primary endpoint is described here by design descriptor only; the endpoint name is not reproduced on this page, and no result, direction or effect is asserted. The endpoint is listed solely to characterise how the study was constructed. Re-check registry status and endpoint names against the primary publication at time of use. Study design only; no effect is asserted for either of the above studies.

How is ipamorelin handled in the laboratory?

The following are bench-chemistry considerations for a research reagent - not use instructions, and not a validated stability protocol. As a C-terminally amidated pentapeptide, ipamorelin is hygroscopic: the lyophilised powder is best stored desiccated and protected from light, with long-term storage typically at -20 C or below. After reconstitution in an appropriate laboratory solvent (added gently down the vial wall; swirl, do not vortex or shake), solutions of peptides in this class are generally held at 2 to 8 C and used within a defined working window for analysis, with freeze-thaw cycles minimised to limit hydrolysis and aggregation. None of this constitutes a preparation method for any use in humans or animals. See the reconstitution guide for the general bench procedure, and handle with standard laboratory PPE in a controlled environment.

For a peptide reference material, the certificate of analysis is the document that substantiates identity and purity for a given lot - typically through mass-spectrometric identity confirmation against the expected mass near 711.9, sequence confirmation, and chromatographic purity by reverse-phase HPLC. A vial that says ipamorelin is not automatically a vial that is ipamorelin. Confirming the lot CoA rather than relying on the label is the appropriate way to verify a received reagent; numeric windows vary between sources, so confirm against the actual lot document at Certificates of analysis.

Where does ipamorelin sit among the related catalogue compounds?

Receptor class is the organising principle here, not indication. Ipamorelin engages the ghrelin / GHS-R1a receptor. CJC-1295 with DAC is a modified GHRH (GRF 1-29) analogue that targets the separate GHRH (GRF) receptor class - mechanistically distinct despite sharing membership of the broader growth-hormone axis. Shared axis does not mean shared pharmacology. The full growth-hormone-axis range is at GH-axis research peptides.

How strong is the evidence, really?

Tier one is solid: the chemistry is unambiguous. CAS 170851-70-4, CID 9831659 and formula C38H49N9O5 converge on a single amidated pentapeptide, and the receptor it engages, GHS-R1a, is the same Gq/11-coupled target the endogenous ligand ghrelin acts on. Tier two is the middle ground: the foundational characterisation rests on in-vitro pituitary-cell work and preclinical animal pharmacology, and a cell in a dish is not a person. Tier three is the thinnest: human evidence here amounts to a single registered randomised trial catalogued by design descriptor alone, with no endpoint result on this page. It is not a licensed medicine, and it has not been shown to produce defined outcomes in humans. Curiosity is warranted; certainty is not.

Research use only

Ipamorelin supplied by Kovalabs is a research reference material intended solely for in-vitro and laboratory research by qualified professionals. It is for research use only and is not a medicine, supplement or food. It is not for human or veterinary use, not for diagnostic use, and not for any form of administration to humans or animals. Nothing on this page constitutes medical, therapeutic or dosing advice, and no clinical benefit, effect or outcome is stated or implied. Purchasers are responsible for handling, storing and using the material in compliance with all applicable laws and institutional safety requirements. Please review the full terms at Research-use disclaimer before purchase.

Frequently asked questions

What is ipamorelin and how is it classified?

Ipamorelin is a synthetic, C-terminally amidated pentapeptide with the sequence Aib-His-D-2Nal-D-Phe-Lys-NH2. It is classified by its molecular pharmacology as a growth-hormone-secretagogue (GHS) peptide that acts as an agonist at the ghrelin / growth-hormone-secretagogue receptor type 1a (GHS-R1a), a Gq/11-coupled G-protein-coupled receptor. This receptor class is distinct from the GHRH receptor engaged by GHRH analogues. Ipamorelin is a research reference material only and is not for human or veterinary use.

What are the verified identifiers for ipamorelin?

PubChem CID 9831659, molecular formula C38H49N9O5, molecular weight 711.9 g/mol (PubChem average; monoisotopic 711.39), InChIKey NEHWBYHLYZGBNO-BVEPWEIPSA-N, and CAS 170851-70-4. These were cross-checked: a PubChem name lookup returns CID 9831659, and an independent reverse lookup of CAS 170851-70-4 resolves back to the same CID with no divergent entry, so the CAS, CID and formula all point to a single molecule. Some vendor sheets quote 711.86 or 711.9 for the mass without stating the basis; confirm against the lot certificate of analysis.

What receptor does ipamorelin act on?

The primary literature describes ipamorelin as a peptidic agonist at the ghrelin / growth-hormone-secretagogue receptor type 1a (GHS-R1a), a Gq/11-coupled G-protein-coupled receptor, which places it in the same receptor grouping as the endogenous ligand ghrelin (Raun K et al., 1998, PMID 9849822). This is a receptor-target characterisation only. No downstream physiological effect or secretory output is asserted or implied, and the receptor class is mechanistically distinct from that of GHRH analogues.

What have published studies on ipamorelin investigated?

The foundational report (Raun et al., 1998, PMID 9849822) was designed around named endpoints including in-vitro GHS-receptor agonist potency and efficacy and, in preclinical animal pharmacology, plasma growth hormone concentration alongside plasma ACTH and cortisol as comparator hormonal endpoints. A later randomised, double-blind, placebo-controlled trial (Beck et al., 2014, NCT00672074) compared intravenous ipamorelin with placebo and carried a pre-specified primary endpoint described here by design descriptor only. All studies are reported by design and endpoint name; no result, magnitude or benefit is stated or implied.

How should ipamorelin reference material be stored and reconstituted in the laboratory?

As a bench procedure for a research reagent: the lyophilised powder is hygroscopic and is best stored desiccated and protected from light, typically at -20 C or below for long-term storage. Reconstitution involves adding an appropriate laboratory solvent gently down the vial wall and swirling rather than shaking. The reconstituted solution is generally held at 2 to 8 C and used within a defined working window for analysis, with freeze-thaw cycles minimised. These are general physicochemical handling considerations, not a validated stability protocol and not a preparation method for any use in humans or animals. See the reconstitution guide at Reconstitution guide and confirm specifics against the lot certificate of analysis at Certificates of analysis.

Is ipamorelin safe or approved for use in people?

This page makes no safety, efficacy or approval claim of any kind. Kovalabs supplies ipamorelin strictly as a research reference material for laboratory investigation by qualified researchers. It is for research use only and is not for human or veterinary use. Full terms are at Research-use disclaimer.

Sources

1. PubChem CID 9831659 - Ipamorelin (formula, MW, InChIKey, synonyms)
2. PubChem RegistryID cross-reference - CAS 170851-70-4 to CID 9831659
3. Raun K et al., Eur J Endocrinol 1998 (PMID 9849822) - GHS receptor characterisation and study design
4. Beck DE et al. Int J Colorectal Dis. 2014;29(12):1527-1534 (DOI 10.1007/s00384-014-2030-8; NCT00672074) - randomised, double-blind, placebo-controlled trial design (clinical endpoint generic, indication omitted)