Ipamorelin

Ipamorelin is a synthetic pentapeptide (Aib-His-D-2Nal-D-Phe-Lys-NH₂) that acts as a selective agonist of the ghrelin / growth hormone secretagogue receptor (GHS-R1a). It was developed in the 1990s by Novo Nordisk as a clean growth-hormone-releasing peptide with minimal cross-reactivity at other GHS-related targets.

Peppudex card: see the mechanism + evidence-grade summary at [Peppudex / Ipamorelin](https://peppudex.com/peptides/ipa-cjc1295).

Overview

Ipamorelin selectively stimulates pulsatile growth hormone release from the anterior pituitary while sparing cortisol, prolactin, and aldosterone. This selectivity differentiates it from older GH-releasing peptides like GHRP-6 and Hexarelin, which also raise stress hormones. The peptide is commonly stacked with CJC-1295 (a GHRH analog) to amplify the GH pulse via dual-pathway activation.

Mechanism

• Binds ghrelin receptor GHS-R1a on pituitary somatotrophs
• Triggers Ca²⁺-mediated release of stored GH
• Does NOT cross-react with V1a vasopressin receptor, CRF receptor, or prolactin pathways
• Half-life approximately 2 hours, dose-pulse profile lasting ~3–4 hours

See: Growth_hormone, Ghrelin_receptor, CJC-1295.

Evidence

• Healthy volunteers · single subcutaneous dose produces a dose-dependent GH pulse with no significant effect on cortisol or prolactin (Raun et al., 1998, PMID 9849822)
• Postoperative ileus · phase II proof-of-concept trial (n=114, IV ipamorelin 0.03 mg/kg twice daily) showed numerical but not statistically significant reduction in time to first tolerated meal (median 25.3 h vs 32.6 h, p=0.15) vs placebo. Beck et al., 2014, Int J Colorectal Dis, PMID 25331030, NCT00672074. The Helsinn / Lilly sponsor program was subsequently discontinued.
• No completed phase III trials for any indication

Dosing literature

Community-reported research dose: 200–300 µg per administration, 1–3 times per day, subcutaneous, ideally on an empty stomach to avoid blunting the GH pulse with elevated blood glucose.

Common stack: ipamorelin 300 µg + CJC-1295 100 µg in the same injection, taken 2–3× daily for 8–12 weeks, then cycled off.

Storage

Lyophilized: 4 °C 24 months. Reconstituted: 2–8 °C, use within 28 days. See Reconstitution.

Regulatory status

• United States. Research use only. Not FDA-approved. Sponsored phase II program discontinued.
• WADA. Prohibited at all times under Section S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics), in the growth-hormone-secretagogue sub-category. ([2026 WADA Prohibited List](https://www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf))

See also

• CJC-1295 · standard stack partner
• Growth_hormone
• GHRP-6 · older, less selective GHS
• [Peppudex card · Ipamorelin](https://peppudex.com/peptides/ipa-cjc1295) · mechanism, evidence grades A-F, FAQs, peer-reviewed sources

References

• Raun K, Hansen BS, Johansen NL, et al. "Ipamorelin, the first selective growth hormone secretagogue." Eur J Endocrinol. 1998;139(5):552-61. PMID 9849822.
• Beck DE, et al. "Safety and efficacy of ipamorelin for the prevention of postoperative ileus: a multicenter randomized phase II trial." Int J Colorectal Dis. 2014;29(12):1527-34. PMID 25331030.
• Sinha DK, et al. "Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males." Transl Androl Urol. 2020;9(Suppl 2):S149-S159. PMID 32257854.