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Ipamorelin

Also identified as NNC 26-0161

Growth-hormone secretagogue (GHRP-type receptor agonist)

Sequence: Aib-His-D-2-Nal-D-Phe-Lys-NH2

Molecular weight
711.9
Molecular formula
C38H49N9O5
CAS
170851-70-4
Published studies reviewed
3

FOR RESEARCH USE ONLY. NOT FOR HUMAN OR VETERINARY USE. NOT FOR HUMAN CONSUMPTION.

Compounds described on this site are supplied solely for laboratory research. They are not offered for human or veterinary use or for clinical use, and they are not intended to diagnose, mitigate, cure or prevent any disease.

Ipamorelin is the synthetic pentapeptide Aib-His-D-2-Nal-D-Phe-Lys-NH2, a growth-hormone secretagogue reported to act at the GHRP-type receptor rather than the GHRH receptor. Three publications are reviewed: the 1998 pharmacology in rat pituitary cells, rats and swine, a 1999 pharmacokinetic study in healthy men, and a 2014 randomised study in adults recovering from bowel surgery. Its selectivity findings come entirely from cells and animals, and the randomised human study did not meet its primary endpoint.

At a glance

Also identified as
NNC 26-0161
Class
Growth-hormone secretagogue (GHRP-type receptor agonist)
Target or mechanism
Agonist — GHRP-type (growth-hormone secretagogue) receptor
Evidence types represented
in vitro, animal, human
Published studies reviewed
3
Last reviewed
2026-09-26

Overview

Ipamorelin is a synthetic pentapeptide, Aib-His-D-2-Nal-D-Phe-Lys-NH2, described in the literature as a growth-hormone secretagogue acting at the GHRP-type receptor rather than at the GHRH receptor.

The publication that characterised it, in 1998, is laboratory and animal work: growth hormone released from primary rat pituitary cells, then from anaesthetised rats, then from conscious swine. Its most-cited finding is one of selectivity — in swine, ipamorelin raised growth hormone without raising ACTH or cortisol beyond what was seen after GHRH stimulation, even at amounts more than 200-fold above the amount producing half-maximal growth hormone release. That finding is real, and it is entirely preclinical.

The human record collected here is two publications. A 1999 study in healthy men measured how ipamorelin and growth hormone moved through the blood across five ascending amounts: a half-life of about 2 hours, and a single growth-hormone peak at roughly 40 minutes that then fell away. It recorded concentrations, not outcomes. The other is a randomised study published in 2014, in adults recovering from bowel resection surgery, whose primary endpoint — the time to a first tolerated standardised solid meal — was not met.

Both are on this page, filed at the tier each belongs to. Nothing here is a statement about the research material PepGenex supplies.

Mechanism under investigation

Ipamorelin
Agonist
  • GHRP-type (growth-hormone secretagogue) receptor

Pharmacological profiling with GHRP and GHRH antagonists, reported in the 1998 publication, placed the compound's growth-hormone-releasing activity at a GHRP-like receptor rather than at the GHRH receptor. That work was done in cells and animals.

Scope of the published work

Areas investigated
  • Growth hormone release
  • Selectivity against ACTH and cortisol release
  • Postoperative bowel recovery
  • Pharmacokinetics
Models used
  • Primary rat pituitary cells
  • Anaesthetised rats
  • Conscious swine
  • Randomised human study
  • Human pharmacokinetic study

The selectivity and potency findings on this page are cell and animal work and do not transfer to people. The one randomised human study recorded here did not meet its primary endpoint. Nothing here is a statement about the research material PepGenex supplies.

Limitations

Evidence represented on this page: in vitro, animal and human. The page reviews 3 published studies, and each figure is reported for the study that published it; results are not pooled across studies.

Common questions

What is Ipamorelin?

Ipamorelin is a synthetic pentapeptide, Aib-His-D-2-Nal-D-Phe-Lys-NH2, described in the literature as a growth-hormone secretagogue acting at the GHRP-type receptor rather than at the GHRH receptor.

How does Ipamorelin work, according to the published research?

Pharmacological profiling with GHRP and GHRH antagonists, reported in the 1998 publication, placed the compound's growth-hormone-releasing activity at a GHRP-like receptor rather than at the GHRH receptor. That work was done in cells and animals.

What has published research on Ipamorelin found, and what are its limits?

This page records 3 publications, reporting laboratory (in vitro) work in 1, animal work in 1, human work in 2. Each is listed with its identifier under References.

Human studies represented: Gobburu et al., 1999, PMID 10496658; Beck et al., 2014, PMID 25331030.

Evidence represented on this page: in vitro, animal and human.

The page reviews 3 published studies, and each figure is reported for the study that published it; results are not pooled across studies.

The selectivity and potency findings on this page are cell and animal work and do not transfer to people. The one randomised human study recorded here did not meet its primary endpoint. Nothing here is a statement about the research material PepGenex supplies.

Is Ipamorelin approved by the U.S. FDA?

This page cites no FDA approval record for Ipamorelin; PepGenex Science states a U.S. regulatory status only where a sourced record exists.

PepGenex research materials are not FDA approved and are not for human or veterinary use.

What risks have published studies of Ipamorelin reported?

1 published human study on this page reports adverse events or safety measurements. Each is listed with its publication in the adverse-events section of this page.

Trial events do not establish a complete safety profile.

What adverse events have been reported in published studies of Ipamorelin?

Adverse events and safety measurements as reported by the published human studies on this page. Each entry is attributed to its publication.

Beck et al., 2014, PMID 25331030

Design and population
Multicentre, double-blind, placebo-controlled proof-of-concept study in adults undergoing small or large bowel resection. 117 were enrolled and 114 formed the safety and modified intention-to-treat populations; ipamorelin or placebo was given from the first day after surgery for up to seven days.
Events reported
Adverse events arising during the study were recorded in 87.5% of the ipamorelin arm and 94.8% of the placebo arm. The publication describes ipamorelin, as given in this study, as well tolerated.

Trial events do not establish a complete safety profile.

Published research

Grouped by the kind of study. Select one to narrow what is shown below.

Preclinical (animal)(1)

Laboratory (in vitro)Preclinical (animal)

Ipamorelin, the first selective growth hormone secretagogue

Raun K, Hansen BS, Johansen NL, et al., European Journal of Endocrinology, 1998;139(5):552-561

published

  • In primary rat pituitary cells, ipamorelin released growth hormone with potency and efficacy similar to GHRP-6 (EC50 1.3 ± 0.4 nmol/l and Emax 85 ± 5%, against 2.2 ± 0.3 nmol/l and 100% for GHRP-6).
  • Profiling with GHRP and GHRH antagonists indicated that ipamorelin, like GHRP-6, stimulates growth hormone release by way of a GHRP-like receptor rather than the GHRH receptor.
  • In pentobarbital-anaesthetised rats, ipamorelin released growth hormone with potency and efficacy comparable to GHRP-6 (ED50 80 ± 42 nmol/kg and Emax 1545 ± 250 ng GH/ml, against 115 ± 36 nmol/kg and 1167 ± 120 ng GH/ml for GHRP-6).
  • In conscious swine, ipamorelin released growth hormone with an ED50 of 2.3 ± 0.03 nmol/kg and an Emax of 65 ± 0.2 ng GH/ml plasma.
  • In swine, none of the growth-hormone secretagogues tested altered FSH, LH, prolactin or TSH concentrations. GHRP-6 and GHRP-2 raised ACTH and cortisol; ipamorelin did not raise either beyond the concentrations seen after GHRH stimulation, including at amounts more than 200-fold above its ED50 for growth hormone release.
Context

This is cell and animal pharmacology. It is the work that characterised the compound and it is careful work, but every number in it was measured in rat cells, in rats or in swine. A selectivity result in swine is a statement about swine; it does not become a statement about a person by being cited often.

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Human study (phase not stated)(1)

Human study (phase not stated)

Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers

Gobburu JV, Agersø H, Jusko WJ, Ynddal L, Pharmaceutical Research, 1999;16(9):1412-1416

published

An ascending-amount study in healthy male volunteers across five amount levels, with eight men at each level. Plasma concentrations of ipamorelin and of growth hormone were measured and described with a population pharmacokinetic–pharmacodynamic model. The abstract does not state the total number of men, does not describe a placebo group, and reports no safety data.

  • The pharmacokinetic parameters were proportional to the amount given, with a short terminal half-life of 2 hours, a clearance of 0.078 L/h/kg and a volume of distribution at steady state of 0.22 L/kg.
  • At every amount level, growth hormone rose as a single episode that peaked at 0.67 hours and then declined exponentially to negligible concentrations. In the model, the plasma ipamorelin concentration giving half-maximal growth hormone stimulation (SC50) was 214 nmol/L and the maximal growth hormone production rate 694 mIU/L/h. Variability between individuals was larger for these response parameters than for the pharmacokinetic ones.
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Human phase 2(1)

Human phase 2n = 117

Beck et al., 2014 (title withheld on this site; see the publication record)

Beck DE, Sweeney WB, McCarter MD; Ipamorelin 201 Study Group, International Journal of Colorectal Disease, 2014;29(12):1527-1534

published

Multicentre, double-blind, placebo-controlled proof-of-concept study in adults undergoing small or large bowel resection. 117 were enrolled and 114 formed the safety and modified intention-to-treat populations; ipamorelin or placebo was given from the first day after surgery for up to seven days.

  • On the key endpoint, median time to a first tolerated standardised solid meal was 25.3 hours in the ipamorelin arm and 32.6 hours in the placebo arm (p = 0.15). The difference was not statistically significant.
  • The publication reports no significant differences between ipamorelin and placebo in the key or the secondary efficacy analyses.
  • Adverse events arising during the study were recorded in 87.5% of the ipamorelin arm and 94.8% of the placebo arm. The publication describes ipamorelin, as given in this study, as well tolerated.
  • The publication states its own limits: the study was small and enrolled people with a broad range of underlying conditions.
What this study establishes

This is the randomised human study, and its key endpoint was not met: the 7.3-hour difference in median time to a first tolerated meal carried a p-value of 0.15, which is the publication's own way of saying the study could not tell that difference from chance. Nothing in the secondary analyses reached significance either.

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Compared with related compounds

Classification, structure, recorded targets, evidence types and FDA status only, each read from the two compounds' own pages. These comparisons do not compare study results.

Ipamorelin and Sermorelin

Growth-hormone secretagogues recorded at different receptors: the GHRP-type receptor, and the growth-hormone-releasing hormone receptor.

IpamorelinSermorelin
ClassificationGrowth-hormone secretagogue (GHRP-type receptor agonist)Growth-hormone-releasing hormone analogue, GHRH (1-29)
StructureSequence Aib-His-D-2-Nal-D-Phe-Lys-NH2; formula C38H49N9O5Sequence Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-NH2; formula C149H246N44O42S
Targets recordedAgonist: GHRP-type (growth-hormone secretagogue) receptorAgonist: Growth-hormone-releasing hormone receptor
Evidence types representedin vitro, animal, humanin vitro, human
Status with the U.S. FDANot shown (no Drugs@FDA application record verified for this page)Drugs@FDA lists two approved applications for sermorelin acetate, and the products under both are listed as discontinued. Source: Drugs@FDA, Applications NDA 019863 and NDA 020443.

Ipamorelin and CJC-1295

Growth-hormone secretagogues recorded at different receptors: the GHRP-type receptor, and the growth-hormone-releasing hormone receptor.

IpamorelinCJC-1295
ClassificationGrowth-hormone secretagogue (GHRP-type receptor agonist)Growth-hormone-releasing hormone analogue
StructureSequence Aib-His-D-2-Nal-D-Phe-Lys-NH2; formula C38H49N9O5Formula C165H269N47O46
Targets recordedAgonist: GHRP-type (growth-hormone secretagogue) receptorAgonist: Growth-hormone-releasing hormone receptor
Evidence types representedin vitro, animal, humanin vitro, animal, human
Status with the U.S. FDANot shown (no Drugs@FDA application record verified for this page)Not shown (no Drugs@FDA application record verified for this page)

Ipamorelin and Tesamorelin

Growth-hormone secretagogues recorded at different receptors: the GHRP-type receptor, and the growth-hormone-releasing hormone receptor.

IpamorelinTesamorelin
ClassificationGrowth-hormone secretagogue (GHRP-type receptor agonist)Growth-hormone-releasing hormone analogue
StructureSequence Aib-His-D-2-Nal-D-Phe-Lys-NH2; formula C38H49N9O5Formula C221H366N72O67S
Targets recordedAgonist: GHRP-type (growth-hormone secretagogue) receptorAgonist: Growth-hormone-releasing hormone receptor
Evidence types representedin vitro, animal, humanhuman
Status with the U.S. FDANot shown (no Drugs@FDA application record verified for this page)An FDA approved drug product containing tesamorelin exists. Source: Drugs@FDA, Application BLA 022505.

References

Published studies reviewed (3)

  1. Ipamorelin, the first selective growth hormone secretagogue — Raun K, Hansen BS, Johansen NL, et al., European Journal of Endocrinology, 1998;139(5):552-561
    DOI 10.1530/eje.0.1390552 · PMID 9849822
  2. Beck et al., 2014 (title withheld on this site; see the publication record) — Beck DE, Sweeney WB, McCarter MD; Ipamorelin 201 Study Group, International Journal of Colorectal Disease, 2014;29(12):1527-1534
    DOI 10.1007/s00384-014-2030-8 · PMID 25331030 · NCT00672074
  3. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers — Gobburu JV, Agersø H, Jusko WJ, Ynddal L, Pharmaceutical Research, 1999;16(9):1412-1416
    DOI 10.1023/a:1018955126402 · PMID 10496658

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