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Compound monograph

Ipamorelin

Ipamorelin is a synthetic pentapeptide with a C-terminal amide, characterized in its original report as a growth hormone secretagogue acting through a GHRP-like receptor rather than the GHRH receptor.

Published: 2026-09-04Last updated: 2026-10-14Literature/identifier verification: 2026-08-23
Also known asNNC 26-0161
Growth hormone secretagogues

01

Identity & nomenclature

Ipamorelin is a synthetic pentapeptide with a C-terminal amide, characterized in its original report as a growth hormone secretagogue acting through a GHRP-like receptor rather than the GHRH receptor.

Identified within a series of compounds lacking the central Ala-Trp dipeptide of growth hormone-releasing peptide-1. PubChem lists NNC 26-0161 as a development identifier.

Declared aliases and development codes: NNC 26-0161.

02

Molecular properties

Molecular formulaC38H49N9O5
Molecular mass711.9 Da
CAS Registry Number170851-70-4
PubChem CID9831659
UNIIY9M3S784Z6
Three-letter sequenceAib–His–D-2-Nal–D-Phe–Lys
Terminal groupsFree N-terminus; C-terminal amide

Pentapeptide Aib-His-D-2-Nal-D-Phe-Lys-NH2. Contains alpha-aminoisobutyric acid, D-2-naphthylalanine, and D-phenylalanine, so a standard one-letter representation does not apply. The sequence is stated identically in the PubChem synonym record and in the original characterization paper.

03

Structural characteristics

Pharmacological profiling using GHRP and GHRH antagonists reported that ipamorelin acts via a GHRP-like receptor. The original report describes it as the first GHRP-receptor agonist whose selectivity for growth hormone release resembled that of GHRH, noting that plasma ACTH and cortisol were not raised significantly relative to GHRH stimulation even at doses more than 200-fold above the ED50 for growth hormone release, in contrast to GHRP-6 and GHRP-2. Structure-activity work on related analogs examined lysine mimetics combined with naphthyl- or biphenylalanine substitutions in the core.

  • Alpha-aminoisobutyric acid (Aib) at position 1
  • D-2-naphthylalanine at position 3
  • D-phenylalanine at position 4

Terminal features: Free N-terminus, C-terminal amide.

04

Molecular targets & mechanisms

Growth hormone secretagogue receptor

GHS-R1a · Ghrelin receptor · GHSR

A G-protein-coupled receptor distinct from the GHRH receptor. Antagonist profiling reported that ipamorelin releases growth hormone through a GHRP-like receptor rather than through the GHRH receptor, establishing the two pathways as separate.

05

Analytical considerations

Three of the five residues are non-proteinogenic, and the C-terminus is amidated. Identity methods must resolve the D-configuration residues and the amide, which a sequence-only assay assuming L-amino acids will not distinguish.

What the studies reported

Each finding describes one cited study in its stated model. These observations are specific to that study and do not establish effects in other settings.

Cell and tissue studies

  • Primary rat pituitary cells

    Raun et al. measured ipamorelin-induced GH release with a reported potency of 1.3 +/- 0.4 nmol/L in primary rat pituitary cells.

    Reference [1]

  • Primary rat pituitary cells

    Raun et al. reported antagonist-profiling results consistent with ipamorelin-induced GH release through a GHRP-like receptor in primary rat pituitary cells.

    Reference [1]

  • Human urine in a liquid-chromatography mass-spectrometry assay

    Thomas et al. reported extraction and liquid-chromatographic mass-spectrometric detection of ipamorelin among the peptides analyzed in human urine.

    Reference [6]

Animal studies

  • Conscious swine

    Raun et al. observed no change in FSH, LH, PRL or TSH plasma levels among the tested GH secretagogues, including ipamorelin, in swine.

    Reference [1]

06

Verified bibliography

Cited studies by type

The 6 papers this record cites, counted by the kind of work each reports. A count is the size of this record's selection, not of the research that exists, and says nothing about results, safety, effectiveness or approval.

A paper can report more than one kind of work. Each count opens those papers in the bibliography. Compare every record on the Evidence Map.

  1. Reference 1

    Ipamorelin, the first selective growth hormone secretagogue.

    Raun K, Hansen BS, Johansen NL, Thøgersen H, Madsen K, Ankersen M, Andersen PH

    European journal of endocrinology · 1998-11 · Journal Article

    current
    PMID 9849822DOI 10.1530/eje.0.1390552IpamorelinGHRP-6GHS-R1a

  2. Reference 2

    Highly potent growth hormone secretagogues: hybrids of NN703 and ipamorelin.

    Hansen TK, Ankersen M, Raun K, Hansen BS

    Bioorganic & medicinal chemistry letters · 2001-07-23 · Journal Article

    current
    PMID 11459660DOI 10.1016/s0960-894x(01)00345-6IpamorelinGHS-R1a

  3. Reference 3

    Ghrelin and glucose homeostasis.

    Delhanty PJ, van der Lely AJ

    Peptides · 2011-03-21 · Review

    current
    PMID 21396419DOI 10.1016/j.peptides.2011.03.001IpamorelinGHS-R1a

  4. Reference 4

    Growth hormone secretagogue receptor family members and ligands.

    Smith RG, Leonard R, Bailey AR, Palyha O, Feighner S, Tan C, Mckee KK, Pong SS, Griffin P, Howard A

    Endocrine · 2001-02 · Review

    current
    PMID 11322507DOI 10.1385/ENDO:14:1:009GHRP-6IpamorelinGHS-R1a

  5. Reference 5

    Structure of an antagonist-bound ghrelin receptor reveals possible ghrelin recognition mode.

    Shiimura Y, Horita S, Hamamoto A, Asada H, Hirata K, Tanaka M, Mori K, Uemura T, Kobayashi T, Iwata S, Kojima M

    Nature communications · 2020-08-19 · Journal Article

    current
    PMID 32814772PMC7438500DOI 10.1038/s41467-020-17554-1IpamorelinGHRP-6GHS-R1a

  6. Reference 6

    Determination of growth hormone releasing peptides (GHRP) and their major metabolites in human urine for doping controls by means of liquid chromatography mass spectrometry.

    Thomas A, Höppner S, Geyer H, Schänzer W, Petrou M, Kwiatkowska D, Pokrywka A, Thevis M

    Analytical and bioanalytical chemistry · 2011-02-06 · Journal Article

    current
    PMID 21298258DOI 10.1007/s00216-011-4702-3Pralmorelin (GHRP-2)Examorelin (Hexarelin)GHRP-6Ipamorelin

Study models of these references

What kind of experiment each cited paper reports, taken from its abstract unless marked. Not a summary of results.

ReferenceStudy models
Raun K et al. 1998Study models reported: in vitro; animal (rat, swine) · from the abstract
Hansen TK et al. 2001Study models reported: in vitro; animal (pig) · from the abstract
Delhanty PJ et al. 2011Review article
Smith RG et al. 2001Review article
Shiimura Y et al. 2020Study models reported: in vitro · from the abstract
Thomas A et al. 2011Study models reported: in vitro · from the abstract

Compare

Catalog listing

Record history

Published 2026-09-04.

  • : Sequence and structure
  • : References
  • : References

Each entry names the parts of this record that changed on that date. Changes to links between records and to catalogue links are not listed. This history covers the tracked record fields; study findings are not listed here.

Cite this record: Purely Peptides Research Library. Ipamorelin. Published 2026-09-04; updated 2026-10-14. https://purelypeptides.org/research/compounds/ipamorelin/

10

Methodology & citation verification

Reference identity is checked against official PubMed metadata. Local deterministic receipts bind each normalized title and canonical metadata record to its verification date. Scientific values remain absent when an authoritative source has not been verified.

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