Ipamorelin
Selective GH-releasing peptide. The usual partner to CJC-1295.
- Primary research area
- GH secretagogue
- Last updated
- Apr 21, 2026
- Reviewed by
- Peptide Examiner editorial team
What it is
Ipamorelin is a synthetic pentapeptide ghrelin-receptor agonist (growth hormone secretagogue) developed in the late 1990s. It selectively stimulates growth hormone release without the substantial prolactin or cortisol elevation seen with earlier ghrelin agonists, which made it an attractive development candidate. It was never brought to FDA approval and is not a marketed drug. It is commonly stacked with CJC-1295 in biohacker GH-axis protocols.
Mechanism of action
Ipamorelin is a growth hormone secretagogue receptor (GHSR) agonist — it mimics ghrelin's effects at the pituitary GH-releasing cells without substantial off-target activity at receptors that would trigger hunger, cortisol release, or prolactin release. Combined with a GHRH analog (like CJC-1295 or sermorelin), it produces synergistic GH release because the two peptides act via complementary receptor systems.
Research history
Phase 2 development by Novo Nordisk in the late 1990s and 2000s for gastrointestinal indications (post-operative ileus, gastroparesis). Development was discontinued without reaching Phase 3 approval. Since then, human clinical research has been minimal; most discussion of ipamorelin in peer-reviewed literature draws on the older Novo Nordisk-era studies and mechanistic work on GHSR agonism.
Current trial status
No active FDA-track clinical development. Research-use-only sales via peptide vendors.
Regulatory status
Not FDA approved. FDA Category 2 (September 2023). Feb 2026 HHS proposed removal. US compounding pharmacies cannot currently prepare it. WADA-prohibited in competitive sport. Full regulatory timeline →
Controversies and open questions
The 'CJC-1295 + ipamorelin' biohacker stack is popular but lacks controlled human trials supporting the benefit claims (muscle gain, fat loss, recovery, sleep quality). Chronic elevation of GH/IGF-1 in healthy adults has the theoretical cancer-risk concerns of the category. Ipamorelin's selectivity advantage over older GH secretagogues is a real pharmacological strength, but selectivity doesn't substitute for outcomes data.
Further reading
Frequently asked
Is ipamorelin legal to compound?
No. FDA Category 2 (September 2023) prohibits US compounding. The February 2026 HHS proposal may change this pending FDA review. Research-peptide vendors sell it 'for research use only' with the usual RUO caveats.
Why is it often paired with CJC-1295?
Complementary receptors. Ipamorelin hits the ghrelin receptor (GHSR-1a); CJC-1295 hits the GHRH receptor. The combined pulse of GH is larger than either alone. It's a mechanistically rational stack — the evidence for benefit at biohacker-typical doses is still thin.
How is it different from MK-677?
Same target receptor (GHSR-1a) but different molecule class. Ipamorelin is a peptide (injection, short half-life). MK-677 is a non-peptide small molecule (oral, long half-life). MK-677 also has appetite-stimulating effects that ipamorelin lacks.
Was it ever FDA approved?
No. Novo Nordisk advanced it through Phase 2 for GI indications in the 1990s-2000s but discontinued before Phase 3. It has no marketing authorization anywhere.