Ipamorelin: the basics
What is it?
A synthetic peptide that activates the ghrelin receptor, one of the signals involved in growth-hormone release.
FDA briefing ↗What do people claim it helps with?
More muscle, less fat, better sleep and recovery. These claims have not been established by dependable treatment trials.
What has research actually shown?
Research examines growth-hormone release and gut movement after surgery. That does not demonstrate a useful fitness, sleep or anti-aging treatment.
FDA briefing ↗Has this been demonstrated in people?
Laboratory and animal work plus limited human studies in specific settings. A hospital gut-motility study cannot establish benefits in healthy users.
FDA briefing ↗What side effects, risks and unknowns should I understand?
Long-term safety is unclear. Serious events occurred in an intravenous hospital study; occurrence does not establish that ipamorelin caused them.
FDA briefing 1 ↗FDA safety information 2 ↗Is it an approved medicine?
No FDA-approved medicine contains this peptide. Availability online or through a clinic does not mean it has been approved.
FDA briefing 1 ↗FDA safety information 2 ↗Approval here means U.S. FDA approval and applies to a particular product, formulation and use. This is a starting overview, not a complete side-effect list. Sources checked 10 October 2026; independent scientific review pending.
How is it used or studied?
Studied using specific research preparations. There is no FDA-approved treatment formulation; an online vial, capsule or spray is not necessarily the product used in a study.
Different routes and formulations can have different effects. A study of one product does not validate every product with the same peptide name.
A common misunderstanding
A combination with CJC-1295 needs its own evidence; results for either ingredient alone do not prove the combination works.
What should I ask a clinician?
- What diagnosis or goal are we trying to address, and what established options are available?
- Was the expected benefit shown in people like me, using this exact product?
- How could my medicines, health conditions or pregnancy plans affect the risks?
- What monitoring is needed, and what would tell us the treatment is helping or should be stopped?
What do the research words mean?
- Peptide
- A short chain of amino acids, the building blocks of proteins.
- Preclinical
- Research in cells, tissues or animals before dependable treatment evidence in people.
- Controlled trial
- A study comparing a treatment with another treatment or a placebo to help separate its effects from other explanations.
- Biomarker
- A measurement, such as a hormone level. A change does not necessarily mean someone feels better or lives longer.
Ipamorelin Evidence & Clinical Profile
Human Study Limits
Ipamorelin has been investigated in clinical contexts. Patient outcomes must be evaluated against study size, design, and control cohorts.
Laboratory & In Vivo Assays
Cellular and animal disease models examine receptor binding affinities and signaling cascades, which require human confirmation.
What is Ipamorelin?
Ipamorelin Pentapeptide Secretagogue is A synthetic pentapeptide ghrelin-receptor (GH secretagogue receptor) agonist. In animal studies it released growth hormone without raising ACTH or cortisol, but a Phase 2 trial found no significant benefit for postoperative ileus. Aliases include: NNC 26-0161, Aib-His-D-2-Nal-D-Phe-Lys-NH2.
- Sequence (one-letter)
- Aib-H-D-2Nal-D-F-K-NH2
- Molecular formula
- C38H49N9O5
- Molecular weight
- 711.9 g/mol
- CAS Number
- 170851-70-4
- UNII Code
- Y9M3S784Z6
- PubChem CID
- 9831659
Identifiers checked against PubChem and FDA's Global Substance Registration System on 13 October 2026. FDA substance record ↗ · PubChem record ↗ See all names and codes in the peptide name index.
Clinical Trials & Human Cohorts
Human research can examine tolerability, symptoms or patient outcomes. The design and comparator determine what each result can establish.
Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients [1]
What was reported
Ipamorelin was well tolerated, but median time to first tolerated solid meal (25.3 vs 32.6 hours) did not differ significantly from placebo (p=0.15).
What limits the conclusion
Small proof-of-concept study enrolling patients with a broad range of underlying conditions; no significant differences in key or secondary efficacy analyses.
Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers [3]
What was reported
Ipamorelin produced a single episode of GH release, peaking at about 0.67 hours, at all dose levels; terminal half-life was about 2 hours.
What limits the conclusion
Single-infusion pharmacology study in healthy men; no clinical outcomes, and other pituitary hormones are not reported in the abstract.
How the compound may work
Mechanisms describe how Ipamorelin may affect biological processes. Laboratory findings and patient outcomes answer different questions.
GHRP-Receptor Agonism
Released GH from primary rat pituitary cells with potency and efficacy similar to GHRP-6; antagonist studies showed it acts through a GHRP-like receptor. [2]
Absence of Off-Target Endocrine Stimuli
Unlike GHRP-6 and GHRP-2, ipamorelin did not raise ACTH or cortisol beyond GHRH-stimulated levels, even at doses over 200-fold the GH ED50; FSH, LH, PRL and TSH were unaffected. [2]
Areas Being Studied
These research topics reflect active areas of scientific exploration, distinct from unverified commercial marketing claims.
Compare the study designs.
| Study | Design / sample | Outcome type | Key limitation |
|---|---|---|---|
| Phase 2 Postoperative Ileus · 2014 [1] | Phase 2 multicenter double-blind placebo-controlled RCT n = 114 |
Clinical endpoint evaluation | Small proof-of-concept study enrolling patients with a broad range of underlying conditions; no significant differences in key or secondary efficacy analyses. |
| Human PK/PD Study · 1999 [3] | Dose-escalation infusion study n = 8 per dose level (5 levels) |
Clinical endpoint evaluation | Single-infusion pharmacology study in healthy men; no clinical outcomes, and other pituitary hormones are not reported in the abstract. |
Regulatory Status & Clinical Safety
Regulatory Classification
Unapproved drug; WADA Category S2 prohibited substance.
Safety Realities & Impurities
Safety depends on the molecule, formulation, route and evidence. A laboratory purity measurement alone cannot establish safety for human use.
Clinical Trials Registry Records
Official registry records from ClinicalTrials.gov. Study registration does not imply government endorsement or guaranteed efficacy.
Safety and Efficacy of Ipamorelin for Management of Post-Operative Ileus [1]
- Planned enrollment
- 117 (patients)
- Posted results
- Pending in registry
- Sponsor
- Helsinn Therapeutics (U.S.), Inc
- Last updated
- 2017
WADA & Anti-Doping Regulations
WADA Section S2: Prohibited Substance
The World Anti-Doping Agency (WADA) classifies Ipamorelin under Section S2 of the Prohibited List. Prohibited at all times (in- and out-of-competition). Last verified: October 2026.
Research Timeline
-
1998
Selective Secretagogue Described
Ipamorelin characterized in rats and swine as the first selective GH secretagogue. [2]
-
2014
Phase 2 Ileus Trial
Published proof-of-concept trial finds no significant efficacy difference from placebo. [1]
-
2026
WADA S2 Prohibition
Prohibited in and out of competition. [4]
What Researchers Still Don't Know
Long-term safety profiles
Multi-year observational data in broader heterogeneous cohorts remains uncharacterized.
Optimal dose-response thresholds
Comparative trials optimizing minimal effective exposure versus adverse event rates.
Formulation bioavailability
Differences between oral, subcutaneous, and modified peptide delivery vehicles.
References
Primary sources verified against PubMed / NLM and regulatory databases.
- Clinical RCT
-
Preclinical Pharmacology
Ipamorelin, the first selective growth hormone secretagogue ↗ (external website)
- Clinical Pharmacology
- Regulatory