Educational ipamorelin guide: the selective ghrelin-receptor (GHS-R1a) GH secretagogue — mechanism, the published human data, the evidence and regulatory status, half-life and side effects. Research/educational use only, not medical advice.
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Educational use only — not medical advice. This guide summarizes information reported in published research and community practice for educational purposes. It is not medical advice and not a recommendation to use any compound. Any doses, schedules, or combinations shown are examples of what has been reported, not instructions for you. Many peptides described here are research compounds that are not FDA-approved for the uses discussed and may be investigational or restricted. Effects, risks, and legal status vary; individual needs and results vary. Consult a qualified, licensed healthcare professional before making any decision. Do not use this content to diagnose, treat, or dose yourself.
Ipamorelin at a glance
What it is
Ipamorelin — a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) and selective agonist of the ghrelin receptor (GHS-R1a), classed as a growth-hormone-releasing peptide (GHRP).
Identity
PubChem CID 9831659 · C38H49N9O5 · MW 711.9 · CAS 170851-70-4 · Novo Nordisk development code NNC-26-0161.
Human record
A PK/PD study in 40 healthy men (PMID 10496658) plus TWO completed Phase 2 efficacy trials, both by Helsinn for post-operative ileus: NCT00672074 (n=117) and NCT01280344 (n=320).
Dose used in humans
Intravenous, 0.03 mg/kg twice daily on post-operative days 1–7 (NCT00672074, published as Beck et al. 2014).
Selectivity
Demonstrated in swine: no ACTH or cortisol rise even at doses over 200-fold above the GH ED50, where GHRP-6 and GHRP-2 both raised them (PMID 9849822).
Plasma half-life
Terminal half-life 2 hours in healthy men after a 15-minute intravenous infusion (PMID 10496658). No subcutaneous human figure has been published.
Regulatory status
Not FDA-approved; development discontinued; WADA-prohibited; research/educational use only.
Educational reference. This page does not publish dose ranges or reconstitution arithmetic.
What it is / mechanism
Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) that selectively agonizes the ghrelin receptor (GHS-R1a) on pituitary somatotrophs, producing a pulsatile release of growth hormone. It was identified at Novo Nordisk within a series of compounds lacking the central Ala-Trp dipeptide of GHRP-1, and the pharmacological profiling that established its receptor was done with GHRP and GHRH antagonists — it behaves like a GHRP, not like a GHRH analog, which is the whole basis of pairing it with one. In primary rat pituitary cells it released GH with an EC50 of 1.3 ± 0.4 nmol/L and an Emax of 85 ± 5%, against GHRP-6 at 2.2 ± 0.3 nmol/L and 100% — comparable potency, slightly lower ceiling.
Researched effects
The defining result is selectivity, and it is worth quoting at the level of detail the original paper reports rather than as an adjective. In conscious swine, none of the secretagogues tested affected FSH, LH, prolactin or TSH. GHRP-6 and GHRP-2 both raised ACTH and cortisol. Ipamorelin did not — not at the effective dose, and not at doses more than 200-fold above its own ED50 for GH release. That is a strong, specific, replicated-in-design finding, and it is what 'the selective GHRP' actually means. Two things follow that most pages leave out. First, it was measured in pigs and rats, not in people. Second, selectivity is a statement about what else the compound does NOT do — it is not evidence that the GH release produces any downstream outcome. Body-composition, recovery and anti-ageing effects discussed in community reports have not been demonstrated in a controlled human trial; the two human trials that exist measured gastrointestinal recovery after bowel surgery, and the first of them missed its primary endpoint.
Evidence & regulatory status
There are TWO completed human Phase 2 trials, not one. Both were run by Helsinn Therapeutics (U.S.) in post-operative ileus: NCT00672074 (n=117, completed) and NCT01280344 (n=320, completed). Earlier versions of this page described 'the one completed human randomized trial', which is wrong, and the larger of the two is the one that was missing. Both records are public on ClinicalTrials.gov.
The published trial gives a real human dose, and it does not resemble the community one. Beck DE, Sweeney WB, McCarter MD and the Ipamorelin 201 Study Group, Int J Colorectal Dis 2014;29(12):1527-34 (PMID 25331030) reports NCT00672074 as a multicentre, double-blind, placebo-controlled Phase 2 study in adults undergoing small and large bowel resection. The intervention was intravenous infusion of 0.03 mg/kg ipamorelin versus placebo, twice daily, from post-operative day 1 to day 7 or discharge. For an 80 kg patient that is about 2.4 mg per infusion — roughly 4.8 mg a day, intravenously, in hospital.
So the gap between the trial and the practice is a route and an order of magnitude. Community reports describe microgram amounts given subcutaneously; the trials infused milligram-per-kilogram amounts intravenously into surgical inpatients for a different purpose. Neither trial studied body composition, sleep or recovery in healthy adults, and no trial has.
There is also a human pharmacokinetic and pharmacodynamic study, which most pages omit entirely: Gobburu JV, Agersø H, Jusko WJ, Ynddal L, Pharm Res 1999;16(9):1412-6 (PMID 10496658). Forty healthy men across five intravenous infusion rates; dose-proportional kinetics, terminal half-life 2 hours, clearance 0.078 L/h/kg, Vss 0.22 L/kg, and a single GH release episode peaking at 0.67 hours with an SC50 of 214 nmol/L. So ipamorelin's human record is three studies, not one: this, plus the two Phase 2 efficacy trials above.
The selectivity data is animal and it is specific: Raun K. et al., 'Ipamorelin, the first selective growth hormone secretagogue', Eur J Endocrinol 1998;139(5):552-61 (PMID 9849822). Rat pituitary EC50 1.3 ± 0.4 nmol/L; anaesthetised rats ED50 80 ± 42 nmol/kg; conscious swine ED50 2.3 ± 0.03 nmol/kg with Emax 65 ± 0.2 ng GH/mL. No ACTH or cortisol response in swine at over 200× the GH ED50.
Regulatory: developed as NNC-26-0161 at Novo Nordisk, later taken into post-operative-ileus trials by Helsinn, and discontinued. Never FDA-approved for any use. WADA-prohibited in competitive sport, with no therapeutic-use exemption available.
Sold and discussed for research and educational use only. There is no long-term human safety dataset — the trials dosed for at most seven days.
Research timeline
Dated milestones taken from the primary records: the molecule's discovery, its first registered human study, the trials that shaped the evidence and the regulatory decisions. Each entry links to the record it comes from.
Novo Nordisk researchers describe ipamorelin as "the first selective growth hormone secretagogue": a five-amino-acid peptide that released growth hormone in rats and pigs about as strongly as GHRP-6, but in pigs, unlike GHRP-6 and GHRP-2, did not raise ACTH or cortisol. PMID 9849822
A dose-escalation study in healthy men: single intravenous infusions are given at five dose levels (eight men per level); each produced one episode of growth-hormone release, and the measured terminal half-life of ipamorelin was about 2 hours. PMID 10496658
A second, larger Phase 2 trial of ipamorelin after bowel resection (320 patients, Helsinn) is completed; as of 4 Oct 2026 its registry record carries no posted results. NCT01280344
A Phase 2 placebo-controlled trial in 114 bowel-surgery patients, sponsored by Helsinn and run from 2008, reports that intravenous ipamorelin did not shorten the time to a first tolerated solid meal or improve any secondary measure of postoperative ileus. PMID 25331030
FDA places ipamorelin acetate in Category 2 of its outsourcing-facility (503B) list, substances that raise significant safety risks, citing immunogenicity, its unnatural amino acids and serious adverse events, including death, reported when it was given intravenously for gut motility. FDA · compounding safety risks, Apr 22, 2026
FDA's Pharmacy Compounding Advisory Committee votes against adding ipamorelin (free base and acetate) to the pharmacy-compounding (503A) list, 0 in favour, 12 against and 1 abstention for each form, citing a lack of safety and efficacy data for growth hormone deficiency and postoperative ileus. FDA · PCAC minutes, Oct 29, 2024
Records checked Oct 4, 2026
Claims at a glance
The claims most often made about this compound, each with the strongest kind of evidence we found for it. The grade says what was studied, not whether the claim is true; the line beside it says what that study showed.
Raises growth hormoneHuman, non-randomised. In 40 healthy men given an intravenous infusion, a single growth-hormone pulse peaking at about 40 minutes, then falling to negligible levels. PMID 10496658
Does not raise cortisol, unlike older GHRPsAnimal studies only. Shown in pigs in the discovery paper (1998): no ACTH or cortisol release beyond the comparator; not measured in people. PMID 9849822
Burns fat and improves body compositionAnimal studies only. The only direct fat measurement, in mice, found relative body fat went up, not down; not measured in people. PMID 11162489
Raises IGF-1Animal studies only. The one measurement found, in adult rats over 15 days, showed no change in total IGF-1. PMID 10373343
Improves sleepNo study found. A PubMed search on 5 Oct 2026 returned one narrative review and no study that measured sleep in any species. PubMed search, Oct 5, 2026
Is well toleratedHuman, randomised trial. In a placebo-controlled trial in 114 hospital patients after bowel surgery, side effects were no more common than on placebo, over about a week. PMID 25331030
The reasoning behind each grade, study by study, is in this guide's Benefit & Outcome Review.
Grades checked Oct 5, 2026
A printable reference sheet with the compound's key facts, storage guidance and a vial record comes with All-Access Lifetime.
Half-life & pharmacokinetics
Two hours — and unusually for this library, that figure is a human measurement with an address. Gobburu, Agersø, Jusko and Ynddal (Pharm Res 1999;16(9):1412-6, PMID 10496658) ran a dose-escalation study in healthy male volunteers: five infusion rates (4.21, 14.02, 42.13, 84.27 and 140.45 nmol/kg, each over 15 minutes), eight men per dose level, forty in total, with both ipamorelin and growth hormone measured. The pharmacokinetics were dose-proportional, with a short terminal half-life of 2 hours, clearance of 0.078 L/h/kg and a steady-state volume of distribution of 0.22 L/kg. The growth-hormone response was a single episode peaking at 0.67 hours and declining exponentially at every dose, with half-maximal stimulation at 214 nmol/L. Two caveats travel with the number and are usually dropped. It is a TERMINAL half-life, which is not the same as the duration of effect — the GH pulse peaks and is gone well inside it. And it was measured after intravenous infusion; no subcutaneous human half-life for ipamorelin has been published, so the figure describes a route almost nobody uses. The community inference that a short half-life is why protocols describe one to three doses a day is reasonable, and the GH time course supports it better than the half-life does.
Reported side effects & toxicology
The best-supported safety statement about ipamorelin is a negative one, and it is animal data: in swine it did not raise ACTH or cortisol at doses more than 200-fold above its GH-releasing ED50, where GHRP-6 and GHRP-2 both did, and no secretagogue tested moved FSH, LH, prolactin or TSH (PMID 9849822). That is the basis for the 'best-tolerated GHRP' reputation, and it is a real finding rather than a marketing line — but it was measured in pigs. On the human side, two Phase 2 trials collected safety data over at most seven days of intravenous dosing in post-surgical patients, which is not a dataset about months of subcutaneous use in healthy adults. Community-reported effects are mild — facial flushing or warmth, mild headache, injection-site reactions — with less appetite stimulation than GHRP-6. As with any GH-axis compound, sustained use is reported to bring water retention, joint aches, tingling and reduced insulin sensitivity, and caution around malignancy and pregnancy is described in the literature.
Storage & handling
Lyophilized (unmixed): store cold and dark; long-term typically frozen.
Reconstituted: refrigerate (~2–8°C); commonly reported usable window ~2–3 weeks; swirl gently, do not shake; do not freeze once mixed.
References
Primary sources cited on this page: Gobburu JV, Agersø H, Jusko WJ, Ynddal L, 'Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers', Pharm Res 1999;16(9):1412-6 (PMID 10496658); Raun K. et al., 'Ipamorelin, the first selective growth hormone secretagogue', Eur J Endocrinol 1998;139(5):552-61 (PMID 9849822); Beck DE, Sweeney WB, McCarter MD and the Ipamorelin 201 Study Group, Int J Colorectal Dis 2014;29(12):1527-34 (PMID 25331030); ClinicalTrials.gov NCT00672074 and NCT01280344 (Helsinn Therapeutics (U.S.), Inc); Hansen TK et al., J Med Chem 1998;41(19):3705-14 (PMID 9733496) for the discovery series; PubChem CID 9831659; the WADA Prohibited List. Verify current regulatory status, as it continues to evolve.
Evidence File
The Ipamorelin Evidence File: Two Completed Phase 2 Trials, One of Them Published
Ipamorelin's public record is small enough to be enumerated completely, and this module enumerates it: every ClinicalTrials.gov record returned under the drug name, the salt name and the Novo Nordisk development code, and every PubMed record filed under the word ipamorelin, inspected one at a time. It sets out what each human study measured, in whom, by which route and at what dose; converts the trial doses into units that can be compared with the figures circulating in community protocols; traces five widely repeated numbers back to the specific document each came from; and states every absence alongside the exact searches that established it.
2 completed Phase 2 trials, 437 patients enrolled between them
Both Phase 2 trials infused ipamorelin, and neither used the community route
5 circulating figures traced back to their origin documents
1.2 to 9.0 mg per intravenous trial infusion
Everything the registry returns under the name ipamorelin
ST-IPAM-201: the trial that gets cited, and the numbers it actually produced
HT-IPAM-202: the 320-patient dose-finding trial that is not on the free guide
The human volunteer study the free guide does not cite
From nanomoles per kilogram to milligrams: what the human doses actually were
Five circulating figures, traced to the documents they came from
One live 2026 registry record, and why it supports nothing
What has not been measured, and the searches that establish it
8 more sections in the Evidence File for Ipamorelin
Unlock the Evidence File, Sourcing File and Benefit & Outcome Review for Ipamorelin for $14 — or every compound in the library, plus the printable reference sheets, for $99.
The sections above this one stay free to read without an account.
Sourcing File
Sourcing Ipamorelin: The Identity Line, the Acetate Arithmetic and Four Named Adulterants
A generic warning that peptides can be counterfeit is worth very little. This module replaces it with numbers specific to ipamorelin: the identity values a certificate has to match, cross-checked between PubChem and the FDA substance registry; the acetate arithmetic that decides how much peptide a labelled milligram actually contains, checked against three separately registered salt forms; the exact mass shift of the one adulterant that forensic laboratories have named for this molecule, alongside the near-mass species that sit close enough to the parent to be missed; and the one failure mode built into ipamorelin's own structure that no mass-spectrometry line on any certificate can detect.
3 acetate stoichiometries registered; a 5 mg label spans 4.61 to 3.99 mg
Gly-ipamorelin, plus 57.02 Da, named in two forensic laboratories' material
2 D-amino acids that no identity-by-MS line can verify
[M+H]+ 712.39; a peak at 769.41 or 754.40 is a different molecule
The identity numbers, cross-checked between two registries
Three registered acetate salts, and what each does to a labelled milligram
What an ipamorelin certificate should carry, field by field
Gly-ipamorelin: an adulterant with a name, a formula and a mass
The two failure modes that sit close to the parent mass
The blind spot: two D-amino acids and an identical mass
A constructed certificate, read line by line
7 more sections in the Sourcing File for Ipamorelin
Unlock the Evidence File, Sourcing File and Benefit & Outcome Review for Ipamorelin for $14 — or every compound in the library, plus the printable reference sheets, for $99.
The sections above this one stay free to read without an account.
Benefit & Outcome Review
Ipamorelin Claim by Claim: Twelve Marketed Outcomes, Graded Against What Was Measured
Ipamorelin is sold on a list of outcomes that the free guide can only describe as community-reported. This module takes each of those outcomes in turn and asks four questions of the underlying paper: what was measured, in which species, against which comparator, and for how long. Every claim is then assigned an evidence tier, from a controlled human study through animal and cell work down to claims with no measurement behind them at all. Several of the supporting studies turn out to say something other than what is attributed to them, and one of them points in the opposite direction.
2 of 12 graded claims have any human measurement behind them
Longest documented human exposure: roughly one to two weeks
The only direct fat measurement gained relative fat, in mice
The only IGF-1 measurement found no change, in rats
The grading scale, and where the marketed claims come from
The claim that survives: one quantified human growth hormone pulse
Selectivity and potency: one claim half right, one claim wrong
Body composition: nothing in humans, and the one direct measurement went the other way
IGF-1, muscle and bone: three animal claims, three qualifications
Appetite, and the awkward fact of the cachexia programme
Sleep, recovery and the CJC-1295 pairing: three claims with no measurement
Tolerability, duration, and a correction the free guide needs
8 more sections in the Benefit & Outcome Review for Ipamorelin
Unlock the Evidence File, Sourcing File and Benefit & Outcome Review for Ipamorelin for $14 — or every compound in the library, plus the printable reference sheets, for $99.
Quick answers about guide scope, access, and educational use context.
Has ipamorelin been tested in humans?
Yes — twice, and more than most peptides sold alongside it. Helsinn Therapeutics completed two Phase 2 trials in post-operative ileus: NCT00672074 with 117 patients and NCT01280344 with 320. Pages describing 'the one human trial' have missed the larger of the two.
What dose did the human trials use?
Intravenous infusion of 0.03 mg/kg twice daily, from post-operative day 1 to day 7 or discharge (Beck et al., Int J Colorectal Dis 2014, PMID 25331030). For an 80 kg patient that is roughly 2.4 mg per infusion. It is a different route and a far larger amount than the subcutaneous figures reported in community use.
What is the ipamorelin half-life?
A terminal half-life of 2 hours, measured in healthy men after a 15-minute intravenous infusion (Gobburu et al., Pharm Res 1999, PMID 10496658), alongside clearance of 0.078 L/h/kg and a steady-state volume of distribution of 0.22 L/kg. It is a real human number, which is rare here — but it is intravenous, and no subcutaneous human half-life has been published. The growth-hormone pulse itself peaks at about 0.67 hours and is gone long before the peptide is.
How is ipamorelin different from other GHRPs?
Selectivity, and it was measured rather than asserted. In conscious swine, GHRP-6 and GHRP-2 raised ACTH and cortisol; ipamorelin did not, even at more than 200 times the dose that releases GH, and no secretagogue tested affected FSH, LH, prolactin or TSH (Raun et al., Eur J Endocrinol 1998, PMID 9849822).
Is ipamorelin FDA-approved?
No. It was developed at Novo Nordisk as NNC-26-0161, taken into two Phase 2 trials by Helsinn for post-operative ileus, and discontinued. The published trial did not meet its primary endpoint.
Why is ipamorelin commonly paired with CJC-1295?
They act on different receptors — ipamorelin on the ghrelin receptor, CJC-1295 on the GHRH receptor. Ipamorelin's receptor was confirmed by profiling against GHRP and GHRH antagonists, so the pairing rests on established pharmacology rather than on inference.
Does ipamorelin increase appetite?
Less than older GHRPs such as GHRP-6, according to both its selectivity profile and community reports. The controlled comparison behind that reputation is the swine work on ACTH and cortisol, not an appetite study in humans.
Does ipamorelin help body composition or recovery?
No trial has tested it. Both human trials measured recovery of gastrointestinal function after bowel resection. Body-composition, sleep and recovery claims are community reports, not trial outcomes.
Is ipamorelin banned in sport?
Yes — it is WADA-prohibited, with no therapeutic-use exemption available in competitive sport.
What are ipamorelin's identity numbers?
PubChem CID 9831659, molecular formula C38H49N9O5, molecular weight 711.9, CAS 170851-70-4, sequence Aib-His-D-2-Nal-D-Phe-Lys-NH2, development code NNC-26-0161. A certificate that disagrees with the formula or the mass is describing something else.
Compliance and trust notes
Educational content only; no personalized health or outcome claims.
No personalized use recommendation outputs.
Use this material for general learning and research-context literacy.
A certificate of analysis (COA) is a laboratory’s report on one sample of one batch. The single most useful thing to know about it is that purity and identity are two separate results that fail in different ways. A high purity figure says the sample was mostly one substance; it does not say that substance was Ipamorelin. Identity — normally a mass-spectrometry result matching the expected molecular weight — is what establishes what the material actually is, and a certificate reporting purity alone has not answered that question.
Two further limits are worth holding onto. Mass per vial is its own test: a vial can be 99% pure and still contain less material than the label claims. And sterility, endotoxin, heavy metals and residual solvent screening are separately commissioned tests, usually priced individually — so a “third-party tested” badge asserts none of them unless the certificate names them. Check that the batch or lot number on the document matches the vial in front of you; an unmatched certificate describes someone else’s material.
Medibact does not test, endorse or resell peptides, and publishes no rating of any laboratory. How to read a peptide certificate of analysis walks through the document section by section, and what each COA field establishes covers the field-by-field detail and the laboratories that publish their methods.
You’ll need bacteriostatic water
The diluent for reconstituting Ipamorelin
Reconstitution is volume arithmetic — it assumes a lyophilized vial is dissolved in bacteriostatic water, which is sterile water preserved with 0.9% benzyl alcohol. The preservative is what allows a vial to be entered more than once; plain sterile water carries none and is single-entry by design. Medibact supplies USP-grade Bacteriostatic Water for Injection in a 30 mL multi-dose vial, produced in an FDA-registered U.S. facility and shipped from the United States, for research use only. One 30 mL vial covers 30 reconstitutions at 1 mL each, 15 at 2 mL, or 10 at 3 mL — division only, not a dosing recommendation.
Educational use only — not medical advice. This guide summarizes information reported in published research and community practice for educational purposes. It is not medical advice and not a recommendation to use any compound. Any doses, schedules, or combinations shown are examples of what has been reported, not instructions for you. Many peptides described here are research compounds that are not FDA-approved for the uses discussed and may be investigational or restricted. Effects, risks, and legal status vary; individual needs and results vary. Consult a qualified, licensed healthcare professional before making any decision. Do not use this content to diagnose, treat, or dose yourself.
