Ipamorelin — Peptide Protocol Wiki reference

At present, there is no documented, reproducible clinical efficacy for ipamorelin in therapeutic indications based on the available evidence.

Overall, this Phase 2‑sized study was underpowered for definitive efficacy, used multiple endpoints, and yielded a negative primary result.

Development status and other potential applications Reviews summarize that despite favorable preclinical efficacy in POI, clinical endpoints were not met in Phase II trials, and development for GI indications was halted.

No robust clinical efficacy data were identified for other proposed uses (e.g., body composition, GH-related indications) within the retrieved evidence; available summaries emphasize limited human data and lack of regulatory approval.

Ipamorelin: Selective GH Secretagogue Guide | Peptide Protocol Wiki Skip to main content 🧬 Peptide Protocol Wiki Peptides Side Effects New Learn Directory Tools Blog News About ⌘K ⌘K 🌱 New to Peptides?

Start the 7-step beginner guide Peptides Side Effects New Directory Learn Tools Blog News About Ipamorelin 📋 Overview 🧬 Molecule 🔄 Similar ⚠️ Side Effects 💉 Dosing 🔬 Research 🚨 Risks 👥 Community 📊 Community Data Home Peptides Ipamorelin Growth Hormone Anti-Aging & Longevity phase2 Ipamorelin Also known as: IPA, NNC 26-0161 Compare with 5 peptide s Research compiled by Peptide Protocol Wiki 📅 Updated February 1, 2026 Citations Verified TL;DR Ipamorelin is a synthetic pentapeptide growth hormone secretagogue that selectively stimulates GH release via the ghrelin (GHS-R1a) receptor.

receptor isoform biology and constitutive activity modulating responses.

It is notable for its selectivity, producing GH release without significantly elevating cortisol, ACTH, or prolactin at effective doses in clinical studies.

Browse all growth hormone peptides → Table of Contents 📌 TL;DR • Selective GH release with minimal cortisol and prolactin elevation • Dose-dependent GH secretion demonstrated in human studies • Favorable safety profile in Phase I/II clinical trials • Synergistic effects when combined with GHRH analogs like sermorelin Community-Reported Side Effects Anecdotal ?

wth hormone secretion for anti-aging, recovery, and body composition 💉 Dosing Amount 200-300 mcg per injection Frequency 1-3 times daily (commonly twice daily: morning and before bed) Duration 8-12 weeks, then 2-4 weeks off 💊 Administration Route SC Schedule 1-3 times daily (commonly twice daily: morning and before bed) Timing On empty stomach; morning fasted, post-workout, and/or 30-60 min before bed 📅 Cycle Duration 8-12 weeks, then 2-4 weeks off Rest Period 4 weeks off between cycles Repeatable Yes Preparation & Storage Diluent: Bacteriostatic water ⚗️ Suggested Bloodwork ( 6 tests) IGF-1 When: Baseline Why: Baseline growth hormone activity Fasting glucose and HbA1c When: Baseline Why: GH peptides can affect glucose metabolism CBC with differential When: Baseline Why: Baseline blood cell counts IGF-1 When: 4-6 weeks Why: Confirm GH elevation Fasting glucose When: 4 weeks Why: Monitor glucose handling IGF-1 When: Ongoing Why: Levels above age-adjusted reference range ⚠️ Levels above age-adjusted reference range 💡 Key Considerations → Best taken on empty stomach (2+ hours after eating) → No carbs/fats 30 min before or after injection → Often stacked with CJC-1295 DAC (weekly) or Mod GRF 1-29 (per injection) for synergistic GH release → Contraindication: Avoid in active cancer or pituitary disorders Subscribe to unlock this content Get weekly peptide research summaries, new study alerts, and protocol updates — fre

Restore access No thanks, continue reading Related Reading Peptide Sermorelin GHRH analog for growth hormone release Peptide CJC-1295 No DAC (Mod GRF 1-29) common stack partner Peptide GHRP-2 growth hormone releasing peptide How Ipamorelin works at the cellular level Overview of Ipamorelin benefits and applications Scientific Details Molecular Formula C38H49N9O5 Molecular Weight 711.85 Da CAS Number 170851-70-4 Sequence Aib-His-D-2-Nal-D-Phe-Lys-NH2 What is Ipamorelin?

Mechanism of Action # Mechanistic overview Ipamorelin is a synthetic pentapeptide growth hormone secretagogue (GHS) that acts as a selective agonist of the ghrelin (growth hormone secretagogue) receptor GHS-R1a, with minimal activity on other pituitary axes.

Two fatal serious adverse events occurred in ipamorelin-treated patients and were considered possibly related to study drug.

In vitro and in vivo data show that ipamorelin stimulates GH release via GHS-R1a on pituitary somatotrophs and through hypothalamic circuits; its GH-releasing effect in pituitary cells is antagonized by the GHS-R1a blocker D-Lys3- GHRP-6 , indicating receptor-mediated specificity.

Receptor interactions and molecular

targets Primary receptor: GHS-R1a, a seven-transmembrane GPCR expressed in pituitary somatotrophs and hypothalamic nuclei (notably the arcuate nucleus).

A truncated isoform, GHS-R1b, lacks signaling capacity and may modulate GHS-R1a; the receptor exhibits constitutive activity (basal signaling).

Broader ghrelin-receptor signaling can also recruit ERK/MAPK and cAMP-potentiating pathways, with

Cellular targets: Somatotrophs (direct GH exocytosis) and hypothalamic NPY /AgRP and GHRH neurons (augmenting endogenous GHRH drive and/or reducing somatostatin tone), plus vagal/enteric neurons mediating orexigenic and prokinetic effects in the gastrointestinal tract.

Signaling pathways downstream of GHS-R1a G protein coupling and proximal signaling: GHS-R1a primarily couples to Gq/11 (e.g., Gα11), activating phospholipase C (PLC).

Ion channel modulation: DAG/PKC and membrane depolarization reduce K+ and Cl− conductances and facilitate L-type Ca2+ channel opening, supporting Ca2+-dependent secretion.

Extended pathways: GHS-R1a/ghrelin signaling can engage ERK/MAPK cascades, potentiate cAMP signaling in some contexts, and modulate PI3K- and AMPK-related pathways in select cell types.

These effects are documented in receptor-expressing systems and peripheral tissues; their contribution in somatotro

phs is consistent with facilitation of secretion and gene expression programs associated with GH release.

Selectivity and functional outcomes Endocrine selectivity: Ipamorelin produces robust, selective GH pulses without significant ACTH/cortisol or prolactin elevations in preclinical and clinical contexts, differentiating it from some other GHSs and from ghrelin.

Systems physiology: Activation of GHS-R1a in hypothalamic circuits (arcuate NPY/AgRP neurons) and on vagal/enteric pathways contributes to orexigenic behavior and enhanced gastrointestinal motility (e.g., accelerated gastric emptying and intestinal transit), consistent with ghrelin-mimetic action.

Structural/isoform considerations and constitutive activity Isoforms: GHS-R1a (366 aa) is the functional signaling receptor; GHS-R1b (~289 aa) is truncated and does not transmit canonical signals.

Co-expression of 1b may modulate 1a function.

GHS-R1a exhibits constitutive activity; inverse agonists can suppress this basal signaling, indicating potential for ligand bias across the ghrelin receptor family.

Phase II program status: A subsequent larger Phase II study (NCT01280344; n≈320) did not demonstrate significant improvements in measurable colonic functions versus placebo; together with the non-significant primary outcome in the initial RCT,

Conclusion Ipamorelin’s mechanism is best summarized as a selective GHS-R1a agonist that, upon receptor engagement on somatotrophs and hypothalamic neurons, activates Gq/11–PLC signaling, producing IP3/DAG, mobilizing intracellular Ca2+ and opening L-type Ca2+ channels to drive Ca2+/PKC-dependent GH exocytosis.

Ipamorelin Mechanism Summary Aspect Evidence-based details Primary receptor and isoforms Functional target: GHS‑R1a (7TM ghrelin receptor) mediates GHS effects; GHS‑R1b is a truncated, non-signaling isoform; receptor displays constituti...

G-protein coupling and proximal signaling Predominant coupling to Gq/11 → PLC → PIP2 hydrolysis → IP3 + DAG → intracellular Ca2+ release; DAG/Ca2+ → PKC activation; depolarization opens L‑t...

Additional pathways modulated GHS‑R1a activation reported to engage ERK/MAPK, potentiate cAMP in some contexts, and signal via PI3K‑related and AMPK pathways in certain tissues;...

Beta-arrestin / biased signaling Direct beta‑arrestin–biased signaling for ghrelin/GHS ligands is limited/indirect in the cited literature; constitutive receptor activity and inver...

Therapeutic Applications # Objective: Provide a comprehensive, evidence-based summary of ipamorelin’s therapeutic applications and documented outcomes in preclinical and clinical research, with specific study results.

Summary of therapeutic applications Gastrointestinal motility/postoperative ileus (POI): Ipamorelin, a selective ghrelin receptor agonist and GH secretagogue, was developed for accelerating recovery of GI function after abdominal surgery.

Preclinical POI models showed prokinetic effects and improved postoperative intake/weight, leading to Phase II clinical testing in bowel resection patients.

Preclinical outcomes Rat POI model (laparotomy and intestinal manipulation): A single IV dose (1 mg/kg) significantly shortened colonic transit time vs vehicle; however, single dosing did not increase cumulative fecal output, food intake, or 48-h weight gain.

Repetitive IV dosing (0.1–1 mg/kg, four doses/day over 48 h) significantly increased cumulative fecal pellet output and food intake; 1 mg/kg increased 48-h body-weight gain.