Ipamorelin
Also referenced as: NNC 26-0161, growth hormone secretagogue
A selective growth hormone secretagogue often paired with GHRH analogues in community protocols.
- Evidence grade
- DPreclinical Research
Preclinical Research
- Regulatory status
- Not FDA Approved
- Human data
- Limited
No registered clinical trials identified
- Last reviewed
- September 1, 2026
Overview
Ipamorelin is a pentapeptide ghrelin receptor agonist developed to stimulate GH release with less effect on cortisol, prolactin and appetite than earlier secretagogues.
Clinical development targeted postoperative ileus rather than body composition, and did not lead to approval.
Why It's Being Studied
- Selective GH release without broader hormonal disturbance.
- Gastrointestinal motility after surgery.
- Bone and body composition endpoints in animal models.
Mechanism of Action
It acts on the receptor for the hunger hormone ghrelin in the pituitary, triggering a pulse of growth hormone.
Ipamorelin is a selective agonist at the growth hormone secretagogue receptor (GHS-R1a), stimulating somatotroph GH release through phospholipase C and calcium signalling. Selectivity claims rest on preclinical data showing minimal ACTH and prolactin release relative to GHRP-6 and GHRP-2.
The growth hormone axis
Tap each stage to see what happens.
Background: Growth Hormone Research
Growth-hormone secretagogues do not contain growth hormone. They signal the pituitary to release the body's own GH, which then raises IGF-1, largely from the liver.
Because the natural feedback loop stays partly intact, GH release remains pulsatile. That distinguishes these compounds from injected HGH — but it does not make them risk-free, and most lack outcome trials.
Research Areas & Routes Studied
- Growth hormone secretion
- Gastrointestinal motility
- Bone
- Subcutaneous injection (research)
- Intravenous (clinical trials)
Evidence Summary
Preclinical characterisation is solid and a clinical programme in postoperative ileus was attempted, but no positive completed efficacy trials support current uses.
Higher tiers carry more weight. Filled tiers have evidence for Ipamorelin; tap to read it.
- Trials in postoperative ileus were conducted; the programme did not produce an approved indication.
2 cited sources spanning 1998–1998.
- Animal study1
- Regulatory document1
Human clinical evidence
- Trials in postoperative ileus were conducted; the programme did not produce an approved indication.
Animal studies
- Rodent studies characterised selective GH release and effects on bone and growth.
Anecdotal / community information
- Widely used in combination protocols for sleep and recovery claims that have no controlled human support.
Reported Adverse Events in Research
- Headache, flushing and injection-site reactions reported in research settings.
- GH secretagogues can raise glucose and IGF-1; long-term consequences are uncharacterised.
Limitations of Current Evidence
- No completed human efficacy evidence for body composition, recovery or sleep.
- Community combination protocols are not clinical standards.
How to Read This Research
- Did the study measure IGF-1 only, or real outcomes such as body composition or function?
- Which receptor does the compound act on — GHRH, ghrelin, or both?
- Were glucose and insulin sensitivity tracked?
- A rise in IGF-1 is a biomarker, not a benefit in itself.
- Tesamorelin's approval is for a specific indication; that evidence does not transfer to other secretagogues.
- GHRH
- Growth-hormone-releasing hormone, made by the hypothalamus.
- IGF-1
- Insulin-like growth factor 1, the main downstream mediator of GH.
- Secretagogue
- A substance that causes another substance to be secreted.
Compare With Other Compounds
| Ipamorelin | CJC-1295 | |
|---|---|---|
| Evidence grade | D — Preclinical Research | C — Early Human Research |
| Regulatory status | Not FDA Approved | Not FDA Approved |
| Human data | Limited | Limited |
| Clinical trials | None identified | None identified |
| Research routes | Subcutaneous injection (research), Intravenous (clinical trials) | Subcutaneous injection (clinical research) |
| Cited sources | 2 | 1 |
Frequently Asked Questions
Research References
- Animal study1998
Ipamorelin, the first selective growth hormone secretagogue
Raun K, et al. · European Journal of Endocrinology - Regulatory document
Registered ipamorelin trials