Ipamorelin
A selective pentapeptide ghrelin receptor agonist studied for growth hormone release without affecting cortisol, prolactin, or appetite.
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What is Ipamorelin?
Ipamorelin is a synthetic pentapeptide developed in the late 1990s by Novo Nordisk as a selective growth hormone secretagogue. It belongs to the growth hormone-releasing peptide (GHRP) family, which acts on the ghrelin receptor (GHS-R1a) to stimulate growth hormone release from the pituitary. Ipamorelin’s defining feature is its selectivity, releasing growth hormone without meaningfully affecting cortisol, prolactin, adrenocorticotropic hormone (ACTH), or appetite. This distinguishes it from earlier-generation GHRPs such as GHRP-2 and GHRP-6, which have more pleiotropic effects.
Ipamorelin is notable in research as one of the most widely studied peptides in growth hormone research, particularly in combination protocols with GHRH analogs such as Modified GRF (1-29) / CJC-1295 no DAC. The selectivity profile makes it a preferred tool in research contexts where elevation of cortisol or prolactin would be confounding. It was initially developed for potential therapeutic applications in growth hormone deficiency and post-operative recovery, though clinical development was ultimately discontinued.
Mechanism of action
Ipamorelin’s mechanisms of action have been investigated across multiple pathways:
- Ghrelin receptor activation: The peptide binds and activates the growth hormone secretagogue receptor (GHS-R1a), the same receptor activated by endogenous ghrelin, triggering Gq/phospholipase C and Gs/cAMP signaling in pituitary somatotrophs.
- Selectivity for GH release: Unlike native ghrelin and earlier GHRPs, ipamorelin produces minimal effects on hypothalamic-pituitary-adrenal axis function, with doses sufficient for robust GH release not meaningfully elevating cortisol, prolactin, or ACTH in research studies.
- No meaningful effect on appetite: Despite acting on the same receptor that drives ghrelin’s orexigenic effects, ipamorelin does not significantly stimulate appetite at GH-releasing doses, distinguishing it from GHRP-6.
- Synergy with GHRH analogs: When co-administered with GHRH receptor agonists, research has documented synergistic GH release through dual receptor pathway activation.
- Functional somatostatin suppression: Ghrelin receptor activation reduces somatostatin tone, removing a brake on GH release and amplifying the response to concurrent GHRH receptor stimulation.
These pathways are characterized in both preclinical models and limited human research.
Research applications
Ipamorelin has been investigated across several research domains, with the most active areas including:
- Growth hormone research: Ipamorelin has been examined in research contexts requiring selective GH release without HPA axis activation. Phase 1 and Phase 2 studies in growth hormone deficiency demonstrated dose-dependent GH release with favorable tolerability profiles.
- Combination protocols with GHRH analogs: The most common research use of ipamorelin involves co-administration with Modified GRF (1-29) / CJC-1295 no DAC, exploiting synergistic effects between ghrelin receptor and GHRH receptor pathways on growth hormone release.
- Post-operative ileus research: Ipamorelin was advanced into Phase 2 trials for post-operative ileus based on the role of ghrelin signaling in gastrointestinal motility, with research examining effects on return of bowel function after abdominal surgery.
- Body composition and recovery research: Studies have examined effects on lean mass, fat mass, and recovery markers, generally finding modest effects consistent with elevated GH/IGF-1 signaling and smaller than those observed with exogenous growth hormone administration.
- Comparative GHRP research: Ipamorelin has served as a research reference for studying selective vs. non-selective ghrelin receptor agonism, contributing to broader understanding of the GHRP family’s pharmacology.
This compound is intended for laboratory research use only. It has not been approved for human therapeutic use by any regulatory agency.
Storage & reconstitution
In its lyophilized form, ipamorelin tolerates ambient temperatures during shipping but should be stored long-term at -20°C, protected from light. Properly stored lyophilized peptide remains stable for 24 months or longer.
Once reconstituted with bacteriostatic water for injection, ipamorelin solutions should be stored refrigerated at 2-8°C and used within 28 days. Avoid repeated freeze-thaw cycles, which can degrade peptide structure and reduce activity.
Visual inspection should be performed before each use. The reconstituted solution should be clear and colorless. Reject any solution that appears cloudy, discolored, or contains visible particulate matter.
For step-by-step reconstitution calculations, see our reconstitution calculator.
For laboratory research use only. The compound described on this page is intended exclusively for in vitro research and laboratory experimentation by qualified researchers and is not for human or veterinary use. It is not a drug, food, dietary supplement, or cosmetic, and has not been approved by the FDA, Health Canada, EMA, or any other regulatory authority for the diagnosis, treatment, cure, mitigation, or prevention of any disease or medical condition. The information provided on this page is for educational and reference purposes only and does not constitute medical advice. By accessing this content you confirm that you are a qualified researcher purchasing for legitimate laboratory purposes.