Ipamorelin

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Selective GHRP — stimulates natural growth-hormone release without cortisol or prolactin spikes.

A 5-residue synthetic pentapeptide characterised as a highly selective growth-hormone secretagogue receptor (GHS-R1a) agonist with minimal reported cross-reactivity at cortisol or prolactin pathways in preclinical models. For laboratory characterisation only.

Ipamorelin is the first GHRP with GHRH-like selectivity, binding GHSR-1a (ghrelin receptor) to stimulate pulsatile GH release with EC50 = 1.3 nmol/L and Emax = 85% comparable to GHRP-6, but without ACTH/cortisol elevation even at >200-fold above GH ED50. Lower plasma clearance (5-fold slower than GHRP-6) with ~50% nasal bioavailability.

In-vitro cAMP and Ca²⁺ mobilisation assays report full agonism at GHS-R1a. Selectivity over ACTH/cortisol axes is the defining feature reported in the discovery literature.

In-vitro / preclinical characterisation only — no clinical or therapeutic claim is expressed or implied. Research use only.

Ipamorelin is a synthetic pentapeptide (GH-secretagogue secretagogue). Ipamorelin is the first GHRP with GHRH-like selectivity, binding GHSR-1a (ghrelin receptor) to stimulate pulsatile GH release with EC50 = 1.3 nmol/L and Emax = 85% comparable to GHRP-6, but without ACTH/cortisol elevation even at >200-fold above GH ED50. Lower plasma clearance (5-fold slower than GHRP-6) with ~50% nasal bioavailability. It has a molecular formula C38H49N9O5, mass 711.85 Da. Its published amino-acid sequence is Aib-His-D-2-Nal-D-Phe-Lys-NH2. Common synonyms in the literature include NNC 26-0161, Peptide secretagogue, and GHRP.

Investigation of Ipamorelin to date is clinical-investigational, with the majority of citations concentrated in animal models and in-vitro assays rather than randomized controlled human trials. Published work referencing Ipamorelin spans Selectivity studies: Direct comparisons with GHRP-2, GHRP-6, and hexarelin demonstrated ipamorelin's unique selectivity. At GH-equivalent doses, ipamorelin showed no significant increase in cortisol or ACTH, while other GHRPs produced dose-dependent elevations. Prolactin effects were also minimal compared to GHRP-2, Dose-response research: Studies in swine and humans showed linear dose-response relationships for GH release up to plateau doses. The predictable pharmacology distinguishes ipamorelin from GHRPs with more complex dose-response curves, and Postoperative ileus trials: Phase 2 clinical trials evaluated ipamorelin for accelerating GI recovery after surgery. While the compound showed GH-independent effects on GI motility via GHS-R1a in the gut, development was discontinued and the compound did not receive approval. Proposed mechanisms in the literature include GHSR-1a agonism: selectively binds ghrelin receptor, confirmed via GHRP antagonist pharmacology (not GHRH pathway) and Pituitary somatotroph activation: directly stimulates GH-producing cells via Gq-protein/calcium signaling. None of this material describes therapeutic outcomes in humans, and No vendor listed here provides dosing guidance for Ipamorelin outside laboratory research.

For the full mechanistic profile, published references, and constraint notes on Ipamorelin, see the Ipamorelin research page. All references cited on that page are peer-reviewed primary literature.

Binding and functional-assay data for Ipamorelin, from peer-reviewed in-vitro pharmacology publications. Values are receptor activity parameters — not clinical outcomes.

Study designs referencing this compound in the published literature. Descriptions cover framework only — phase, participant count, duration, and citation — not outcomes. Click a card to review the source directly.

Two peptide research compounds published as growth-hormone-secretagogue-family molecules with distinct receptor targets. Reference chemistry only.