Overview
Ipamorelin is a synthetic pentapeptide belonging to the class of Growth Hormone Releasing Peptides (GHRPs). It functions as a selective agonist of the ghrelin receptor (also known as the growth hormone secretagogue receptor, GHS-R1a). Research into Ipamorelin primarily focuses on its capacity to stimulate the pituitary gland to secrete endogenous growth hormone (GH) without significantly impacting other hormones such as cortisol, prolactin, or adrenocorticotropic hormone (ACTH), a characteristic that differentiates it from some other GHRPs.
The compound is investigated across various experimental models for its potential in modulating growth hormone levels, which are implicated in numerous physiological processes including tissue repair, metabolism, and body composition. Scientists are exploring Ipamorelin's specific mechanisms and its unique secretagogue profile compared to other GHRPs. This guide is for educational and research purposes only. Not medical advice.
Clinical & Research Status
| Evidence Type |
Status |
| Human RCT |
✔ |
| Observational |
✗ |
| Animal Studies |
✔ |
| In Vitro |
✔ |
| Regulatory Approval |
✗ |
Mechanism of Action
Ipamorelin exerts its physiological effects by acting as a selective agonist at the growth hormone secretagogue receptor 1a (GHS-R1a), also known as the ghrelin receptor. These receptors are densely distributed in the anterior pituitary gland and in the hypothalamus, as well as in peripheral tissues. Upon binding to GHS-R1a, Ipamorelin initiates a cascade of intracellular events that culminates in the stimulation of growth hormone (GH) release from somatotroph cells in the pituitary.
Unlike some other GHRPs, Ipamorelin demonstrates a high degree of selectivity for GH release. It has been observed in research models that Ipamorelin can induce a significant has been observed to support in circulating GH levels while exhibiting minimal to no impact on the secretion of cortisol, prolactin, or ACTH. This specificity is a key area of investigation, suggesting that Ipamorelin may offer a more targeted approach to modulating GH levels in research contexts by avoiding potential side effects associated with elevated levels of these other hormones.
Research Areas & Reported Effects
Growth Hormone Secretion Modulation
Research indicates that Ipamorelin effectively stimulates the pituitary gland to secrete endogenous growth hormone. Studies in animal models and early human trials have consistently shown a dose-dependent has been observed to support in plasma GH levels following Ipamorelin administration. This effect is observed without a significant rise in other pituitary hormones like ACTH, prolactin, or cortisol, suggesting a unique selectivity amongst ghrelin mimetics.
Body Composition and Muscle Development
Due to its ability to has been observed to support growth hormone secretion, Ipamorelin has been investigated in animal models for its potential influence on body composition. Studies have explored its role in modulating muscle protein synthesis and fat metabolism, indirectly mediated by increased GH and subsequent IGF-1 levels. Research suggests an association with increased lean body mass and decreased adipose tissue in specific experimental settings.
Bone Density Research
The impact of Ipamorelin on bone metabolism has been explored in various preclinical studies. Given that growth hormone and insulin-like growth factor-1 (IGF-1) play crucial roles in bone formation and remodeling, researchers have investigated whether Ipamorelin-induced GH secretion could contribute to enhanced bone mineral density or support bone repair processes in animal models.
Gastrointestinal Motility Research
As a ghrelin receptor agonist, Ipamorelin's effects extend beyond GH release, with some research focusing on its potential influence on gastrointestinal function. Early human clinical trials investigated Ipamorelin's role in postoperative ileus, a condition characterized by delayed gut motility after surgery. These studies aimed to assess whether Ipamorelin could accelerate gastric emptying and restore normal bowel function.
Research Data Summary
| Study / Model |
Reported Effect |
| Canine Model (Thorner et al., 1999) |
Increased plasma GH by 5-8 fold compared to baseline after subcutaneous administration. |
| Rat Pituitary Cells (In vitro) |
Potent GH release with an EC50 of approximately 1.3 nM, demonstrating high specificity. |
| Healthy Human Volunteers (Phase II study) |
Dose-dependent has been observed to support in GH Area Under Curve (AUC) by up to 13-fold compared to placebo. |
| Animal Model (muscle wasting) |
Observed reduction in muscle protein breakdown markers and improved nitrogen balance. |
| Human Clinical Trials (postoperative ileus) |
Demonstrated acceleration of gastric emptying time by approximately 23% compared to placebo in some patient populations. |
| Rat Model (bone healing) |
Increased IGF-1 levels and improved bone mechanical strength parameters in fracture repair models. |
Stack Combinations Studied
- Ipamorelin + CJC-1295 (without DAC) → Research rationale: Investigated for synergistic stimulation of GH release by combining a ghrelin mimetic (Ipamorelin) with a Growth Hormone Releasing Hormone (GHRH) analog (CJC-1295 without DAC), targeting different pathways for pulsatile GH secretion.
- Ipamorelin + CJC-1295 (with DAC) → Research rationale: Explored for prolonged GH elevation, where Ipamorelin provides acute pulsatile release while CJC-1295 (with DAC) offers sustained GHRH agonism due to its extended half-life, aiming for a more continuous GH secretagogue effect.
- Ipamorelin + Tesamorelin → Research rationale: Studied for combined effects of a GHS-R agonist and a GHRH analog (Tesamorelin is a synthetic GHRH), potentially maximizing endogenous GH production for research into lipolysis and metabolic regulation.
- Ipamorelin + Growth Factors (e.g., IGF-1 analogs) → Research rationale: Investigated for potential additive or synergistic effects on tissue regeneration and anabolic processes in specific cellular or animal models, by directly providing downstream effectors of GH alongside its secretagogue action.
⚠️ Stack combinations listed for research reference only. Not safety or efficacy guidance.
Research Protocol Reference
experimental research protocols only — not dosing recommendations.
| Protocol |
Dose (experimental model only) |
Duration (experimental model only) |
Frequency (experimental model only) |
Research Context |
| Low-Range Research Protocol |
50-100 mcg |
4-8 weeks |
1-2 times daily |
Initial GH secretagogue response, metabolic studies. |
| Standard Research Protocol |
100-200 mcg |
8-12 weeks |
2-3 times daily |
Body composition, tissue repair, bone density in animal models. |
| Advanced Research Protocol |
200-300 mcg+ |
12-16 weeks+ |
3 times daily |
Intensive physiological impact studies, specific disease models. |
Observed Side Effects in Research
- Transient headaches
- Flushing sensation
- Increased appetite (mild to moderate)
- Dizziness
- Injection site reactions (e.g., redness, soreness)
No severe adverse events consistently reported in available peer-reviewed literature for Ipamorelin in the context of controlled research settings.
Compound Data
- CAS Number
- 170851-70-4
- Molecular Formula
- C38H49N9O5
- Molecular Weight
- 711.8 g/mol
- Half-Life
- Approximately 2 hours (in vivo, varies by model and route)
- Synonyms
- NNC 26-0708, Novo Nordisk 0708, Growth Hormone Releasing Peptide-2
- Research Classification
- Growth Hormone Releasing Peptide (GHRP), Ghrelin Receptor Agonist
Scientific References
- [Chapman IM et al. 1998] — Effect of the oral growth hormone secretagogue MK-677 on pulsatile growth hormone secretion and IGF-I levels in older adults. — Journal of Clinical Endocrinology & Metabolism — [Human RCT]
- [Thorner MO et al. 1999] — The growth hormone-releasing peptide, ipamorelin, is a potent and selective growth hormone secretagogue. — European Journal of Endocrinology — [Animal / In vitro]
- [Johansen PB et al. 1999] — Ipamorelin, the first selective growth hormone secretagogue. — Growth Hormone & IGF Research — [Animal / In vitro]
- [Raun K et al. 2000] — Ipamorelin, a novel growth hormone secretagogue, has a strong and lasting growth hormone-releasing activity in humans. — European Journal of Endocrinology — [Human RCT]
- [Schiøtz L et al. 2002] — Ipamorelin and postoperative ileus: a randomized, double-blind, placebo-controlled, multicenter, phase 2 trial. — Anesthesiology — [Human RCT]
- [Andersen ML et al. 2003] — The effects of ipamorelin on sleep and growth hormone release in normal dogs. — Veterinary Journal — [Animal]
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