Also known as: NNC 26-0161, IPA
Half-life: ~2 hours
Ipamorelin is a synthetic pentapeptide growth hormone secretagogue that selectively stimulates the release of growth hormone from the pituitary gland. Unlike earlier GH secretagogues such as GHRP-6 and GHRP-2, Ipamorelin does not significantly increase cortisol, prolactin, or appetite, making it one of the cleanest and most selective GH-releasing peptides available. It acts primarily through the ghrelin receptor (GHS-R1a) but with a specificity profile that sets it apart from other ghrelin mimetics.
In preclinical and clinical studies, Ipamorelin has demonstrated dose-dependent GH release comparable to GHRP-6 but without the associated hunger stimulation and hormonal side effects. This selectivity is attributed to its specific binding characteristics at the GHS-R1a receptor, which favor GH release while minimizing off-target signaling. The peptide has also been studied in clinical trials for postoperative ileus (delayed bowel recovery after surgery), where it showed modest benefits in accelerating gut motility.
Ipamorelin is most commonly used in combination with CJC-1295 (Mod GRF 1-29), as the two peptides work through complementary pathways to synergistically amplify GH release. CJC-1295 mimics GHRH to stimulate GH synthesis and release, while Ipamorelin acts through the ghrelin pathway to trigger a pulse of GH secretion. This combination is considered by many in the peptide community to be the gold standard for peptide-based GH optimization.
Ipamorelin was developed by Novo Nordisk in the mid-1990s as part of their growth hormone secretagogue program. It was first characterized in 1998 by Raun et al. as the first selective GH secretagogue — meaning it stimulated GH release without significantly affecting cortisol, prolactin, or other hormones. This selectivity distinguished it from earlier secretagogues like GHRP-6 and GHRP-2. Novo Nordisk conducted Phase 2 clinical trials for postoperative ileus but ultimately discontinued clinical development. The peptide gained widespread popularity in the wellness and anti-aging community, particularly in combination with CJC-1295 (Mod GRF 1-29).
Ipamorelin is considered one of the best-tolerated growth hormone secretagogues. Its selectivity for GH release without significant elevation of cortisol or prolactin gives it a notably cleaner side-effect profile than GHRP-6 or GHRP-2. The most common side effects are mild head rush or flushing immediately after injection, which resolves within minutes, and transient water retention. Unlike GHRP-6, it causes minimal appetite stimulation. Long-term tolerability data from human clinical trials (though limited) has not revealed significant safety concerns.
Dose Range
100-300 mcg
Frequency
Two to three times daily (SubQ)
Duration
8-12 weeks
Dose Range
100-200 mcg
Frequency
Two to three times daily
Duration
8-12 weeks
Dosing information is for educational purposes only. Consult a healthcare professional before using any peptide.
Typical Vial Size
5 mg
Water Type
Bacteriostatic water (BAC water)
Mixing Volume
2 mL
Half-Life
~2 hours
Molecular Weight
711.9 Da
Store reconstituted vial refrigerated at 2-8°C. Use within 28 days. Best administered on an empty stomach, ideally before bed for synergy with natural GH pulse.
FDA Status
Not FDA approved for human use. Clinical development discontinued by Novo Nordisk.
Legal Status
Unregulated research chemical. Prohibited by WADA.
USA
Not approvedClinical development discontinued
EU
Not approvedNot authorized as medicinal product
UK
Not approvedClassified as research chemical
Australia
Not approvedTGA has not evaluated
Russia
Not approvedAvailable as research compound
Canada
Not approvedNot authorized for human use
Raun K, Hansen BS, Johansen NL, Thogersen H, Madsen K, Ankersen M, Andersen PH
European Journal of Endocrinology (1998)
First characterization of Ipamorelin as a selective GH secretagogue, demonstrating potent GH release without significant effects on ACTH, cortisol, prolactin, or FSH/LH.
View Study →Andersen NB, Malmlof K, Johansen PB, Andreassen TT, Frystyk J, Oxlund H
Growth Hormone & IGF Research (1999)
Demonstrated that Ipamorelin can counteract glucocorticoid-induced bone loss in rats, suggesting potential musculoskeletal benefits beyond GH release.
View Study →Gobburu JV, Agersoe H, Jusko WJ, Ynddal L
Pharmaceutical Research (1999)
Established the pharmacokinetic and pharmacodynamic profile of Ipamorelin in healthy volunteers, confirming dose-dependent GH release with a favorable safety profile.
View Study →Long-acting growth hormone releasing hormone analog for sustained GH and IGF-1 elevation.
FDA-approved GHRH analog for HIV-associated lipodystrophy with potent GH-releasing activity.
Fat-metabolizing fragment of human growth hormone without growth-promoting effects.
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