Ipamorelin
Also known as: ipamorelin acetate, NNC 26-0161, nnc260161
Selective GH secretagogue and ghrelin mimetic studied for growth hormone release with minimal side effects.
Quick Reference
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Overview
Peptide selective agonist of the ghrelin/growth hormone secretagogue receptor
Ipamorelin (INN; development code NNC 26-0161) is a peptide selective agonist of the ghrelin/growth hormone secretagogue receptor (GHS) and a growth hormone secretagogue. It is a pentapeptide with the amino acid sequence Aib-His-D-2-Nal-D-Phe-Lys-NH2 that was derived from GHRP-1.
Mechanism of Action
Binds ghrelin receptor (GHS-R1a), selectively stimulates pulsatile GH release without elevating ACTH or cortisol.
What is Ipamorelin?
Ipamorelin is a five-amino-acid peptide studied as a growth hormone secretagogue. In published research, it selectively signaled the ghrelin receptor to prompt growth hormone release while showing far less spillover onto stress and reproductive hormones than older compounds in its class. That selectivity is why researchers keep reaching for it in laboratory studies. It is not FDA approved.
How It Works - Simply Explained
Ipamorelin mimics part of the ghrelin signal at the growth hormone secretagogue receptor in the pituitary gland. When researchers apply it in studies, the pituitary releases growth hormone in pulses that resemble the body's natural rhythm more closely than the flat elevation older drugs caused. The exciting part for scientists is what it does not do: unlike earlier secretagogues, it showed minimal effect on ACTH, cortisol, and prolactin in published tests.
What Studies Have Found
Introduced as the first selective growth hormone secretagogue
In the landmark characterization study, researchers described ipamorelin as the first growth hormone secretagogue designed for selectivity. In animal models, it triggered robust growth hormone release while barely nudging the other pituitary hormones that older compounds in the GHRP family disturbed. That selectivity finding is the reason ipamorelin became a laboratory favorite.
Raun et al., 1998, European Journal of Endocrinology
Minimal cortisol and prolactin spillover
One of the most cited findings is what did not happen: at doses that strongly stimulated growth hormone, ipamorelin produced little to no meaningful rise in ACTH, cortisol, or prolactin. Older secretagogues like GHRP-6 raised those hormones noticeably, which muddied research results. Ipamorelin's cleaner profile lets scientists study growth hormone signaling with less interference.
Raun et al., 1998, European Journal of Endocrinology
Synergy with GHRH: the one-two punch
Researchers found that combining ipamorelin with growth hormone-releasing hormone produced a bigger growth hormone pulse than either compound alone. The two act through different receptors that converge on the same pituitary cells, and the amplified response confirmed the pathways work together. This synergy is why the two are so often studied as a pair.
Bowers et al., early 2000s, growth hormone secretagogue literature
A cleaner tool for long research programs
Follow-up preclinical work reinforced ipamorelin's reputation for specificity across species tested. Because it avoids the appetite-stimulating and prolactin-raising baggage of earlier secretagogues, researchers consider it one of the most precise instruments available for studying pulsatile growth hormone release in the lab.
Ghrelin receptor agonist review literature, 2000s, Endocrine Reviews
Last updated 2026-10-06. New findings are added as published research appears.
Frequently Asked Questions
What is ipamorelin?
Ipamorelin is a synthetic pentapeptide studied as a selective growth hormone secretagogue. It signals the ghrelin receptor to prompt growth hormone release. Researchers value it for its selectivity: it stimulates growth hormone with minimal effect on cortisol, ACTH, or prolactin. It is for laboratory research only and is not FDA approved.
How is ipamorelin different from GHRP-6 or GHRP-2?
GHRP-6 and GHRP-2 are older secretagogues that also raise cortisol, prolactin, and appetite-related signals. Ipamorelin was specifically characterized as the first selective option: strong growth hormone release with far less spillover onto those other hormones, giving researchers cleaner experimental results.
Is ipamorelin FDA approved?
No. Ipamorelin is an investigational research compound. It has not been approved by the FDA for any use, and products sold online are for in-vitro laboratory research only, not for human consumption.
Why do researchers pair ipamorelin with CJC-1295?
Published research showed the two amplify each other: ipamorelin acts through the ghrelin receptor while CJC-1295 acts through the GHRH receptor, and together they produced larger growth hormone pulses than either alone. Studying them as a pair is a well-established research pattern.
Does ipamorelin raise cortisol?
In the published characterization studies, ipamorelin showed minimal effect on ACTH and cortisol at doses that strongly stimulated growth hormone. That selectivity, especially compared with older secretagogues, is one of its most cited properties.
What did animal studies find?
Animal studies reported dose-dependent growth hormone release with high specificity for the ghrelin receptor pathway. Researchers observed preserved pulsatile secretion patterns and a favorable selectivity profile versus earlier compounds in the same class.
Can I use ipamorelin personally?
No. Ipamorelin from research suppliers is for laboratory research only. It is not for human consumption, has not been evaluated by the FDA, and is not a medicine. This page describes published research only.
What Researchers Are Saying
Community Reports - Not Medical Advice
The following is aggregated from public forums, Reddit, and research communities. These are anecdotal reports from researchers only - not verified clinical data and not a recommendation of any kind.
Ipamorelin (also known as ipamorelin acetate, NNC 26-0161) is studied within the growth hormone axis and body composition research community. Selective GH secretagogue and ghrelin mimetic studied for growth hormone release with minimal side effects.
Last updated October 28, 2026
Research status: active. Ipamorelin appears across growth hormone axis and body composition research forums and academic literature. Researchers note this compound falls in the growth hormone category.
Last updated October 28, 2026
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