Ipamorelin (GH Secretagogue)

Ipamorelin is a selective pentapeptide ghrelin mimetic that binds the growth hormone secretagogue receptor type 1a (GHSR-1a) on pituitary somatotrophs with high affinity and specificity. Unlike first-generation GHRPs (GHRP-2, GHRP-6), Ipamorelin stimulates GH release without significantly elevating cortisol, prolactin, or ACTH — a selectivity profile documented by Raun et al. (1998, PMID: 9241518). Receptor binding activates Gq/11 protein signalling and IP3/DAG second messengers, raising intracellular calcium and triggering GH exocytosis. Ipamorelin does not affect appetite-regulating pathways with the same potency as GHRP-6, making it a cleaner research model for isolated GH secretagogue effects. It is typically studied alongside CJC-1295 (GHRH analog) to simultaneously stimulate both the ghrelin and GHRH receptor pathways, producing synergistic GH pulse amplification.

What is Ipamorelin?

Ipamorelin is a selective pentapeptide growth hormone secretagogue (GHS) that stimulates pituitary GH release by mimicking ghrelin at the GHSR-1a receptor — without the cortisol, prolactin, or ACTH elevation associated with earlier GHRPs, making it the cleanest GH secretagogue in the research literature and the most common partner peptide in CJC-1295/Ipamorelin combination stacks. First characterised by Raun and colleagues at Novo Nordisk in 1998 (PMID: 9241518), Ipamorelin was designed to deliver potent GH stimulation with a selectivity profile that makes it tractable for isolated study of GH-axis effects without confounding stress-hormone activation.

Mechanism of Action

Ipamorelin is a full agonist at the growth hormone secretagogue receptor 1a (GHSR-1a), a G-protein coupled receptor (GPCR) expressed on anterior pituitary somatotrophs. Binding activates Gq/11 protein signalling, generating IP3 and DAG second messengers that raise intracellular calcium, triggering exocytosis of stored GH granules and stimulating GH gene transcription.

Unlike GHRP-6 and GHRP-2, Ipamorelin's binding geometry at GHSR-1a achieves GH stimulation without significant cross-activation of adrenocorticotropic hormone (ACTH), cortisol, or prolactin release pathways. Raun et al. (1998) confirmed this selectivity in rats, pigs, and dogs, showing Ipamorelin doses producing maximal GH release caused negligible cortisol or ACTH elevation.

For research purposes, Ipamorelin is typically combined with a GHRH-analog (most commonly CJC-1295 without DAC) to simultaneously activate both receptor pathways on somatotrophs — the GHSR-1a (ghrelin pathway) and the GHRHR (GHRH pathway). This dual stimulation produces synergistic GH pulse amplification greater than either peptide alone.

Key mechanistic features:

• Selective GHSR-1a agonism — Potent GH release without cortisol/ACTH/prolactin elevation
• Gq/11 → Ca²⁺ signalling — Intracellular calcium rise triggers GH exocytosis
• Pulsatile GH release — Preserves physiological GH pulse pattern; feedback loop intact
• Synergy with GHRH analogs — CJC-1295 + Ipamorelin: dual-receptor amplification
• IGF-1 axis stimulation — Secondary hepatic IGF-1 upregulation through elevated GH

Key Research

Raun et al., 1998 (Eur. J. Endocrinol., PMID: 9241518) — Original characterisation of Ipamorelin's selectivity profile. Compared Ipamorelin to GHRP-6 and GHRP-2 across multiple species, confirming equivalent GH stimulation with dramatically lower cortisol and ACTH activation. Established Ipamorelin as the reference compound for selective GHS research.

Johansen et al. (Novo Nordisk series) — Multiple studies characterised Ipamorelin's dose-response, duration of action, and receptor specificity. Demonstrated that Ipamorelin did not trigger tachyphylaxis (receptor desensitisation) with repeated dosing in the same frequency as GHRP-6.

Research Applications

Researchers studying Ipamorelin typically investigate:

• GH pulse amplitude and frequency — GHSR-1a activation dose-response in somatotroph models
• Cortisol/ACTH selectivity — Comparative studies with GHRP-6 and GHRP-2
• CJC-1295 synergy — Dual-receptor GH amplification in stacked models
• Body composition — Lean mass preservation and adipose modulation in GH-deficient models
• Bone mineral density — GH-mediated osteoblast activity markers

Physical Properties

Frequently Asked Questions

What is Ipamorelin used for in research? Ipamorelin is used to study selective GH secretagogue effects, the ghrelin receptor pathway in GH regulation, and as a component of dual-receptor GH stimulation stacks (with CJC-1295). Its clean cortisol/ACTH selectivity makes it the preferred GHRP for research applications where isolated GH-axis effects are needed.

What are the best peptides for anti-aging GH research? Ipamorelin combined with CJC-1295 (no DAC) is the most commonly studied GH-axis anti-aging stack. Sermorelin is the alternative GHRH-axis tool. Ipamorelin + CJC-1295 is preferred when researchers want to activate both the ghrelin and GHRH receptor pathways simultaneously. Sermorelin is preferred for studies of isolated GHRH receptor biology.

How does Ipamorelin compare to GHRP-6? Both are GHSR-1a agonists producing equivalent GH stimulation, but Ipamorelin does not significantly elevate cortisol, ACTH, or prolactin — side effects documented with GHRP-6. For research applications where stress-axis confounding is a concern, Ipamorelin is the preferred compound.

Is Aevitas Ipamorelin research-grade? Yes. Aevitas Ipamorelin is supplied at ≥98% HPLC purity, verified by a third-party laboratory. Every batch ships with a numbered certificate of analysis. Research Use Only — not for human consumption.

Aevitas Ipamorelin — Research Grade

Aevitas supplies Ipamorelin as a lyophilized powder at ≥98% HPLC purity, independently verified by a third-party laboratory. Every batch ships with its certificate of analysis.

Research Use Only — Not for human consumption.

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