Ipamorelin
A selective growth hormone secretagogue that stimulates pulsatile GH release without driving up hunger hormones, cortisol, or prolactin.
Ipamorelin Biological Classification
A selective growth hormone secretagogue that stimulates pulsatile GH release without driving up hunger hormones, cortisol, or prolactin.
Selective GHS-R1a Binding
Binds ghrelin receptors with high affinity, prompting growth hormone secretion.
Spares Stress Hormones
Does not significantly stimulate ACTH, cortisol, or prolactin secretion.
What is Ipamorelin?
Ipamorelin is a synthetic five-amino-acid pentapeptide and selective agonist of the growth hormone secretagogue receptor (GHS-R1a, or ghrelin receptor).
Why are people interested in it?
Unlike older growth hormone secretagogues (such as GHRP-6 or GHRP-2) that cause intense hunger spikes and drive up stress hormones, ipamorelin is celebrated for its selectivity — stimulating growth hormone pulses without spiking cortisol, prolactin, or appetite.
Primary Research Categories
- Growth hormone secretagogues
How does it work in the body?
Ipamorelin binds specifically to the ghrelin receptor on the pituitary gland, mimicking the natural trigger for growth hormone release in a pulsatile pattern.
Receptor Selectivity
Selective Pituitary Ghrelin Receptor (GHS-R1a) Activation
What Ipamorelin Stimulates:
- ✔ Sharp, episodic growth hormone (GH) secretory spikes
- ✔ Preserved somatotropic pulsatility without receptor exhaustion
- ✔ Elevated circulating IGF-1 through natural liver pathways
What It Spares (Unlike GHRP-2/6):
- ✗ Minimal to no rise in ACTH or cortisol (stress hormone)
- ✗ Minimal to no rise in prolactin (glandular stimulation)
- ✗ Significantly milder appetite surge compared to GHRP-6
Selective GHS-R1a Binding
Binds ghrelin receptors with high affinity, prompting growth hormone secretion.
Spares Stress Hormones
Does not significantly stimulate ACTH, cortisol, or prolactin secretion.
What has actually been demonstrated in humans?
Evaluated in early Phase 1 and Phase 2 trials for postoperative bowel recovery (ileus), but development was terminated when it failed to show sufficient efficacy. No human clinical trials exist for body composition, athletic performance, or anti-aging.
Pharmaceutical Reality vs. Unregulated Research Chemicals
Ipamorelin is an unapproved investigational peptide. It was placed on FDA Category 2 compounding restriction lists due to safety and quality concerns.
What is still uncertain or unknown?
Clinical trials were discontinued in Phase 2. Controlled data examining chronic use for fat loss, muscle mass preservation, or longevity in healthy adults does not exist.
Clinical Perspectives & Expert Discussions
Explore all perspectivesWhat identifiable clinicians, researchers, and professional bodies have publicly discussed regarding Ipamorelin.
Dr. William A. Seeds, M.D.
Board-certified Orthopedic Surgeon; founder of Seeds Scientific Research & Performance (SSRP) Institute; Medical Director of Redox Medical Group; author of Peptide Protocols.
Dr. Seeds details the clinical distinction between continuous GHRH exposure and physiological pulsatile secretagogues. He argues that short-acting GHRH analogues (like Mod GRF 1-29 or sermorelin, paired with ipamorelin) are preferable for cellular health because they stimulate natural pituitary pulses while preserving negative feedback loops, whereas long-acting continuous stimulation (such as CJC-1295 DAC) risks pituitary receptor desensitization.
Dr. Edwin Lee, M.D., F.A.C.E.
Board-certified in Internal Medicine and Endocrinology, Diabetes and Metabolism; Fellow of the American College of Endocrinology; founder of the Clinical Peptide Society.
Dr. Lee emphasizes that any clinical exploration of growth hormone secretagogues must be accompanied by comprehensive baseline and ongoing laboratory evaluation, including serum IGF-1, fasting insulin, HbA1c, and cancer screening. He cautions that secretagogues are biologically active molecules that influence cellular proliferation and glucose counter-regulation.
Dosing Reference
Open Ipamorelin Dosing ReferenceNo approved product exists. Human data are limited to pharmacology studies of the compound itself; everything beyond those studies comes from lower source tiers.
Therapept separates official product labels, published clinical study interventions, animal research, clinical references, and community-reported ranges — never blended into one number.
Research at a Glance
Open the full evidence file (5 records)5 records in this file
- CLINICAL TRIAL1
- ANIMAL1
- REVIEW1
- REGULATORY2
Publication span: 1998–2026
What Has Actually Been Studied
- Safety and efficacy of approved and unapproved peptide therapies for musculoskeletal injuries and athletic performance (Sports Medicine, 2026) — Narrative review.
- WADA Prohibited List — S2.2.4 growth hormone secretagogues (WADA Prohibited List, 2026) — Anti-doping listing.
- FDA 503B Category 2 — ipamorelin acetate (added 29 September 2023) (FDA compounding communications, 2023) — Regulatory listing.
- Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers (Pharmaceutical Research, 1999) — Human pharmacokinetic / pharmacodynamic study.
Plus 1 more record in the evidence file.
What is Still Unknown
What we know
- Preclinical pharmacology (Raun 1998) characterised it as a selective GH secretagogue in the systems tested.
- A volunteer PK/PD study (Gobburu 1999) modelled GH release in humans. That is a hormone-axis experiment, not an approved indication.
- It is on FDA's active 503B Category 2 table (added 29 September 2023). GHRP-2 and Kisspeptin-10, also in this library, are on the same active table.
Editorial reading of the records below, labelled as Therapept analysis. How records are built
What remains uncertain
- Controlled human data on clinical disease endpoints.
- Whether commercial material containing unnatural amino acids is characterised to the standard FDA's Category 2 note flags as difficult.
Combinations and Stacks
- CJC-1295 + Ipamorelin
Discussed as a GHRH-analogue plus GH-secretagogue pairing intended to stimulate GH release through two pathways at once — the “synthetic GH axis” pairing.
Preparation and Handling
Lyophilized peptides ship as freeze-dried powders; whatever happens next involves diluents, concentrations and storage conditions that are compound- and product-specific.
United States Regulatory Status
FDA compounding Category 2
- No approved drug product exists in Drugs@FDA.
- Ipamorelin acetate is on FDA's active 503B Category 2 table, added 29 September 2023 — bulk drug substances that may present significant safety risks when used in compounding.
- FDA's published concerns include immunogenicity risk from aggregation and impurities, and the difficulty of characterising an API containing unnatural amino acids.
- A separate 503A nomination was withdrawn by the nominator.
WADA Anti-Doping Status
Named at S2.2.4 among growth hormone secretagogues. Prohibited at all times; non-Specified.
Technical Chemical SpecificationsClick to view CAS, sequence, and molecular formulas
- Molecular weight
- 711.9 g/mol
- Sequence length
- 29 chars
- CAS number
- 170851-70-4
- PubChem CID
- 9831659
- Compound class
- Growth hormone secretagogue; ghrelin receptor (GHS-R1a) agonist. Synthetic pentapeptide containing unnatural amino acids
- Sequence
- Aib-His-D-2-Nal-D-Phe-Lys-NH2
- Molecular formula
- C38H49N9O5
- Molecular weight
- 711.9 g/mol
- CAS number
- 170851-70-4
- PubChem CID
- 9831659
Sources
Last reviewed 3 September 2026 · Compiled by Therapept Editorial · How these records are built