Ipamorelin
Selective growth hormone secretagogue that acts at the ghrelin receptor.
Also known as: NNC 26-0161
Ipamorelin is a synthetic pentapeptide that binds the ghrelin receptor and stimulates growth hormone release from the pituitary gland. It was developed by Novo Nordisk in the 1990s and early 2000s but was never commercialized as an approved drug. It remains available as a research peptide.
Key facts
- Class
- Growth hormone secretagogue (GHS) / ghrelin receptor agonist
- Structure
- Pentapeptide (five amino acids)
- Originator
- Novo Nordisk (development code NNC 26-0161)
- Regulatory status
- Never approved as a drug; research use only
- Receptor target
- Growth hormone secretagogue receptor (GHSR-1a), also known as the ghrelin receptor
What is ipamorelin?
Ipamorelin is a synthetic peptide developed as a selective growth hormone secretagogue. It was designed to stimulate release of growth hormone without significant effects on other pituitary hormones such as cortisol, prolactin, or luteinizing hormone, which distinguishes it from earlier GH secretagogues like GHRP-6 and hexarelin.
Novo Nordisk advanced ipamorelin into early clinical trials in the late 1990s and early 2000s, primarily investigating its use for post-surgical recovery and muscle wasting conditions. The program was eventually discontinued and ipamorelin was never brought to market as an approved medicine.
Mechanism of action
Ipamorelin binds to the growth hormone secretagogue receptor 1a (GHSR-1a), the same receptor activated by the endogenous hormone ghrelin. Activation of this receptor on pituitary somatotrophs triggers release of stored growth hormone into circulation. Growth hormone in turn stimulates production of insulin-like growth factor 1 (IGF-1) from the liver and peripheral tissues.
- •Binds the ghrelin receptor (GHSR-1a) on pituitary somatotrophs
- •Triggers release of stored growth hormone into circulation
- •Reported selectivity: minimal effects on cortisol, prolactin, aldosterone, and ACTH at typical research doses
- •Growth hormone release is pulsatile and subject to negative feedback
Research history
The initial characterization of ipamorelin was published by Raun and colleagues in the European Journal of Endocrinology in 1998. Subsequent preclinical and early clinical work evaluated its effects on growth hormone release in rodents, pigs, and humans. Published data indicate dose-dependent GH release with a relatively clean selectivity profile.
A clinical study of ipamorelin for postoperative ileus, published in 2013, examined its effects in patients recovering from abdominal surgery. The trial did not establish the efficacy needed to advance to phase 3, and ipamorelin was not pursued further by its originator.
Safety and regulatory context
Ipamorelin is not approved by the FDA or any other regulatory agency for any indication. The World Anti-Doping Agency prohibits growth hormone secretagogues, including ghrelin receptor agonists, under section S2 of its Prohibited List at all times.
Published safety data from early clinical trials did not identify major acute safety signals at the doses studied, but long-term data and real-world safety information are lacking. Material sold as research ipamorelin is intended strictly for laboratory use and is not cleared for human administration.
Research sourcing
Ipamorelin is listed by our research partner, GLP1 Research Lab, which supplies lyophilized peptides for laboratory use. Listings include product identifiers relevant to research documentation.
View Ipamorelin listing at GLP1 Research LabAffiliate partnership. Metabolic Playbook may earn a commission on purchases made through this link at no additional cost to the researcher.