Ipamorelin

Ipamorelin (also known as NNC 26-0161) is a anti-aging research peptide. A pentapeptide ghrelin mimetic renowned for its exceptional receptor selectivity. Unlike other GHSRs, Ipamorelin does not significantly raise cortisol, ACTH, or prolactin — making it a clean research tool for isolated GH axis studies.

Ipamorelin is a pentapeptide growth hormone secretagogue (GHS) that acts as a selective agonist of the growth hormone secretagogue receptor (GHSR-1a). Its defining characteristic is its exceptional hormonal selectivity: at effective GH-releasing doses, it does not significantly elevate cortisol, ACTH, aldosterone, or prolactin — unlike older GHRPs (GHRP-2, GHRP-6) which non-selectively activate multiple neuroendocrine pathways. This selectivity makes it a valuable research model for studying isolated GH axis effects. It exhibits a short half-life (~2h) with rapid, physiological GH pulses.

1 Mechanism of action

Selective agonist of GHSR-1a (ghrelin receptor) in pituitary and hypothalamus. Stimulates pulsatile GH release without activating downstream ACTH or cortisol pathways. Synergizes with GHRH analogs (e.g., CJC-1295).

Primary targets: GHSR-1a

2 Reported effects

Effects below are those reported in the published literature cited on this page. They are not claims of clinical benefit and not medical advice.

2.1 Reported benefits

• Selective GH release without cortisol or ACTH elevation
• Increased bone mineral density in animal models
• Synergistic GH amplification when co-administered with GHRH analogs
• Preserves physiological pulsatile GH release pattern

2.2 Side effects

• Transient hunger (ghrelin receptor activation)
• Injection site reactions
• Headache in some protocols
• Water retention at high doses

3 Chemical and physical properties

3.1 Amino acid sequence

4 Research dosages

100–300 μg SC 2–3x daily in research protocols; often combined with CJC-1295 (100 μg each).

5 Research studies (8)

1. Ipamorelin, a New Growth Hormone Releasing Peptide, in Dogs and Pigs
   Journal of Endocrinology (1999) · Preclinical · N=32 (dogs/pigs)
   Landmark selectivity study. Ipamorelin released GH with same potency as GHRP-6 but without cortisol or ACTH elevation — establishing its receptor selectivity profile.
   Key finding: Equivalent GH release to GHRP-6 with zero cortisol or ACTH elevation — unique selectivity among GHSRs.
2. Effects of GHSRs on Bone Mineral Density: Role of Ipamorelin
   Growth Hormone & IGF Research (2001) · Preclinical · N=40 (rats)
   Ipamorelin chronic administration increased bone mineral density and body weight in rats, consistent with GH/IGF-1 pathway activation.
   Key finding: Chronic Ipamorelin increased BMD by 8–12% and lean body mass in rats — GH/IGF-1 mediated effects without cortisol side effects.
3. 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
   Physiology & behavior (2024) · Preclinical
   Anamorelin inhibited cisplatin-induced acute emesis following intracerebroventricular but not intraperitoneal administration, suggesting that brain penetration is important for its anti-emetic mechanism of action.
4. The influence of ghrelin agonist ipamorelin acetate on the hypothalamic-pituitary-testicular axis in a cichlid fish, Oreochromis mossambicus
   Animal reproduction science (2024) · Preclinical
   I phase and that this effect might be mediated via the stimulation of 11-KT and androgen receptors at the testicular level and LH at the pituitary level in the tilapia.
5. Determination of growth hormone releasing peptides metabolites in human urine after nasal administration of GHRP-1, GHRP-2, GHRP-6, Hexarelin, and Ipamorelin
   Drug testing and analysis (2015) · Preclinical
   Our results confirm that the detection window after GHRPs administration depends on individual metabolism, drug preparation form and the way of administration.
6. Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients
   International journal of colorectal disease (2014) · RCT · n=114
   There were no significant differences between ipamorelin and placebo in the key and secondary efficacy analyses.
7. Efficacy of ipamorelin, a ghrelin mimetic, on gastric dysmotility in a rodent model of postoperative ileus
   Journal of experimental pharmacology (2012) · Preclinical
   These results suggest that ipamorelin accelerates gastric emptying in a rodent model of postoperative ileus through the stimulation of gastric contractility by activating a ghrelin receptor-mediated mechanism involving cholinergic excitatory neurons.
8. Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus
   The Journal of pharmacology and experimental therapeutics (2009) · Preclinical
   The results suggest that postsurgical intravenous infusions of ipamorelin may ameliorate the symptoms in patients with POI.

6 Safety and risk profile

6.1 Regulatory status

Ipamorelin is currently classified as Investigational. It has no approved human indication in the United States; availability elsewhere does not imply demonstrated safety or efficacy.

Safety score: 62/100 — moderate concern. Derived from clinical data volume, known risks and regulatory status.

6.2 Contraindications

Conditions and populations in which use is contraindicated:

• Active malignancy (IGF-1 concern)
• Uncontrolled diabetes (GH-induced insulin resistance)
• Proliferative diabetic retinopathy
• Pregnancy and lactation

6.3 Drug interactions

6.4 Long-term risks

• Insulin resistance with prolonged GH elevation
• Pituitary receptor desensitization at high doses
• IGF-1-mediated cancer risk (theoretical)
• Arthralgia and carpal tunnel with chronic use

6.5 Research best practices

• Store at −20 °C; reconstitute with bacteriostatic water
• Administer fasted for maximal GH response (food blunts GH release)
• Injection 30–60 min before sleep aligns with natural GH surge
• Rotate injection sites to prevent lipoatrophy

7 Frequently asked questions

What makes Ipamorelin different from other GHRPs?

Ipamorelin is the most selective GHSR agonist available — it produces significant GH release without the cortisol, ACTH, or prolactin spikes seen with GHRP-2/6 and Hexarelin. This makes it the cleanest tool for studying isolated GH axis effects.

Why is it usually paired with CJC-1295?

Ipamorelin activates the ghrelin receptor (GHSR) while CJC-1295 activates the GHRH receptor. Together they create a synergistic GH pulse 2–3x larger than either alone — amplifying GH while preserving physiological pulsatility.

How long does the GH elevation last?

A single Ipamorelin dose produces a GH pulse lasting approximately 2–3 hours, closely mimicking the body's natural pulsatile GH release pattern. This is in contrast to exogenous GH which produces supraphysiological sustained levels.

8 References

1. 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 PubMed (2024). Lu Z, et al.. View source
2. The influence of ghrelin agonist ipamorelin acetate on the hypothalamic-pituitary-testicular axis in a cichlid fish, Oreochromis mossambicus PubMed (2024). Gouda M, et al.. View source
3. Determination of growth hormone releasing peptides metabolites in human urine after nasal administration of GHRP-1, GHRP-2, GHRP-6, Hexarelin, and Ipamorelin PubMed (2015). Semenistaya E, et al.. View source
4. Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients PubMed (2014). Beck DE, et al.. View source

9 See also

• Peptide encyclopedia index
• Peptide reconstitution calculator
• Glossary of peptide research terms