Ipamorelin
Published research and evidence base
Ipamorelin is a synthetic pentapeptide growth hormone secretagogue that acts as a selective agonist at the growth hormone secretagogue receptor 1a (GHS-R1a, the ghrelin receptor). It was first characterised in 1998 as the first secretagogue in its class to release growth hormone with potency comparable to GHRP-6 while not significantly elevating ACTH or cortisol above levels seen after GHRH stimulation. Preclinical work has examined longitudinal bone growth, bone mineral content, gastrointestinal motility, nociception and cisplatin-induced weight loss, and human pharmacokinetic-pharmacodynamic modelling has been published. Clinical development advanced to a randomised placebo-controlled phase 2 trial in postoperative ileus after bowel resection, which did not meet its primary endpoint; recent literature consists largely of narrative reviews on unapproved performance-enhancing and therapeutic peptides.
- Studies cited
- 15
- Published 2023+
- 9
- Newest paper
- 2026
- Last reviewed
- Aug 2026
Recurring themes in the literature
- GH secretagogue
- ghrelin receptor
- GHS-R1a agonist
- selective GH release without ACTH/cortisol rise
- postoperative ileus
- gastric motility
- longitudinal bone growth
- GH-IGF-1 axis
- anti-doping detection
- unapproved peptide therapy
Compound identifiers
- CAS
- 170851-70-4
- PubChem
- 9831659
What Ipamorelin is, chemically.
- Molecular formula
- C38H49N9O5
- Molecular weight
- 711.9 g/mol
- CAS number
- 170851-70-4
- PubChem CID
- 9831659
NNC-26-0161
These figures come from the PubChem record for this compound and describe the free base. Lyophilised peptide is normally supplied as an acetate or trifluoroacetate salt and carries residual water, so the mass of powder in a vial is not the same quantity as the molecular weight above would suggest. Chromatographic purity on a certificate of analysis does not resolve that difference either — how to read a certificate of analysis explains why.
15 published studies.
Ordered by strength of study design, then by recency. Every entry links to its source record so the finding can be checked against the paper rather than taken on our word.
- 01Human clinical2014
Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients
Beck DE, Sweeney WB, McCarter MD; Ipamorelin 201 Study Group · International Journal of Colorectal Disease · randomised, placebo-controlled phase 2 proof-of-concept trial, n=114 bowel resection patients
Ipamorelin was reported as well tolerated in patients recovering from bowel resection. It did not produce a statistically significant difference from placebo in time to first tolerated meal.
- 02Human clinical1999
Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers
Gobburu JV, et al. · Pharmaceutical Research · dose-escalation study in healthy human volunteers
The analysis characterised dose-proportional kinetics and an elimination half-life of approximately two hours. Pharmacodynamic modelling described episodic growth hormone release across the dose range studied.
- 03Animal in vivo2024
The growth hormone secretagogue receptor 1a agonists, anamorelin and ipamorelin, inhibit cisplatin-induced weight loss in ferrets: Anamorelin also exhibits anti-emetic effects via a central mechanism
Lu Z, et al. · Physiology & Behavior · ferret model of cisplatin-induced emesis and weight loss
Both GHS-R1a agonists inhibited cisplatin-induced weight loss during the delayed phase. Anti-emetic activity was observed with anamorelin following intracerebroventricular administration, indicating a central site of action that was not reproduced by ipamorelin.
- 04Animal in vivo2024
The influence of ghrelin agonist ipamorelin acetate on the hypothalamic-pituitary-testicular axis in a cichlid fish, Oreochromis mossambicus
Gouda M, Ganesh CB · Animal Reproduction Science · 21-day dosing (5-30 µg) in the cichlid fish Oreochromis mossambicus
Ipamorelin acetate produced dose-dependent increases in germ cell development and androgen receptor expression. Luteinizing hormone and 11-ketotestosterone levels were elevated, consistent with action along the hypothalamic-pituitary-testicular axis.
- 05Animal in vivo2012
Efficacy of ipamorelin, a ghrelin mimetic, on gastric dysmotility in a rodent model of postoperative ileus
Greenwood-Van Meerveld B, et al. · Journal of Experimental Pharmacology · rodent model of surgically induced gastric dysmotility
Ipamorelin improved measures of delayed gastric emptying in a rodent postoperative ileus model. The findings were used to support evaluation of the compound for postoperative gastrointestinal dysmotility.
- 06Animal in vivo2009
Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus
Venkova K, et al. · Journal of Pharmacology and Experimental Therapeutics · rat model of postoperative ileus following abdominal surgery
Single-dose ipamorelin shortened the time to first bowel movement after surgery. Repeated dosing increased faecal output and food intake relative to control.
- 07Animal in vivo1999
Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats
Johansen PB, et al. · Growth Hormone & IGF Research · 15-day subcutaneous dosing in rats, multiple dose groups
Ipamorelin dose-dependently increased longitudinal bone growth and body weight gain over 15 days. Circulating IGF-I and markers of bone resorption were not significantly altered.
- 08Animal in vivo1998
Ipamorelin, the first selective growth hormone secretagogue
Raun K, et al. · European Journal of Endocrinology · in vitro pituitary assays plus in vivo studies in rats and swine
Ipamorelin, a pentapeptide, released growth hormone with potency comparable to GHRP-6. Unlike other secretagogues examined, it did not release ACTH or cortisol at levels significantly different from those observed after GHRH stimulation, even at high doses.
- 09Review2026
Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance
Mendias CL, Awan TM · Sports Medicine · narrative review of approved and unapproved peptide therapies
The review noted that many unapproved peptides, including growth hormone secretagogues, showed favourable outcomes in animal models while rigorous human safety data remained scarce. The authors set out a framework addressing efficacy uncertainty, product quality and placebo effects.
- 10Review2026
The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration
Dominikowski A, et al. · Frontiers in Endocrinology · narrative review of GH-IGF-1 axis peptides including ipamorelin
The authors stratified GH-axis peptides by evidence tier and proposed a clinical assessment algorithm for patients self-administering them. Uncertainties around efficacy and potential mitogenic risk were highlighted.
- 11Review2026
Injectable Peptides in Sports Medicine: A Structured Narrative Review of Evidence, Safety, and Antidoping Implications
Villegas Meza AD, et al. · JBJS Reviews · structured narrative review of injectable peptides used in sports medicine
The review concluded that most regenerative and growth hormone peptides remained investigational with uncertain safety profiles. Use was recommended to be limited to approved agents or formal research protocols.
- 12Review2026
Peptide Supplements and Their Therapeutic Applications in Sports Medicine
Tewari K, et al. · The American Journal of Sports Medicine · review of peptide supplements marketed for musculoskeletal recovery and performance
The authors stated that claimed benefits of emerging peptide supplements remained unsubstantiated by current human trials despite promising animal findings. Cardiovascular and metabolic safety concerns were noted.
- 13Review2026
Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians
Mayfield CK, et al. · The American Journal of Sports Medicine · primer-style review covering commonly encountered injectable peptides
The review reported that human orthopaedic outcome data remained largely absent despite preclinical signals. The authors concluded that further safety and efficacy research was required before definitive recommendations could be made.
- 14Review2026
Therapeutic Peptides in Aesthetic, Metabolic and Endocrine Conditions: Effects, Safety, Clinical Applications, and Future Perspectives
Renke G, Chinellato L · International Journal of Molecular Sciences · review of therapeutic peptides across aesthetic, metabolic and endocrine indications
The review surveyed peptides used in metabolic and endocrine settings, including growth hormone secretagogues. The authors concluded that further study was needed before most newer peptides could be considered safe for human use.
- 15Review2026
Therapeutic peptides in gerontology: mechanisms and applications for healthy aging
Mavrych V, Shypilova I, Bolgova O · Frontiers in Aging · review of nine peptides with proposed applications in ageing biology
Ipamorelin was discussed among growth hormone modulators examined in the context of healthspan. The authors reported that investigational peptides in this group lacked long-term data and required rigorous clinical validation.
What this evidence does not establish.
No randomised controlled trial has demonstrated a clinical benefit of ipamorelin on any efficacy endpoint; the largest human trial, in postoperative ileus, did not separate from placebo, and development for that indication did not proceed. Long-term human safety, effects on body composition, bone or musculoskeletal recovery, and outcomes in non-surgical populations remain unstudied, and the recent literature consists almost entirely of narrative reviews rather than new primary data.
Common questions about the research.
- What is Ipamorelin?
Ipamorelin is a synthetic pentapeptide agonist of the growth hormone secretagogue receptor (GHS-R1a). It was characterised in 1998 as the first selective growth hormone secretagogue — selective in the sense that GH release occurred without the ACTH and cortisol response reported for earlier peptides of the same class.
- How does it differ from CJC-1295?
The two act on different receptors. Ipamorelin is a ghrelin-receptor (GHS-R1a) agonist; CJC-1295 is an analogue of growth hormone-releasing hormone acting at the GHRH receptor. Published human work reports that the two pathways stimulate GH release synergistically, which is the rationale behind the combined vials that appear in the research literature.
- How long does it stay in circulation?
Human volunteer data describe a terminal half-life of approximately two hours, a clearance of 0.078 L/h/kg, and a volume of distribution at steady state of 0.22 L/kg, with dose-proportional pharmacokinetics across the range studied.
Available from our catalog
For research purposes only. Not for human consumption, diagnosis, treatment, or prevention of any condition. Nothing on this page is medical advice, and no study summarised here should be read as a recommendation.