// Growth Hormone Secretagogue Research

Ipamorelin:
The Selective
GH Peptide

A research guide to Ipamorelin — one of the most selective and well-tolerated growth hormone secretagogues studied. Mechanism, protocols, and clinical evidence.

How It Works GHS Comparison
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This site is for informational and research purposes only. Ipamorelin is not approved by the FDA for human use. Nothing here constitutes medical advice. Consult a licensed healthcare provider before considering any peptide protocol.

// Quick Reference

Ipamorelin at a Glance

Classification
GHRP-5
5th generation growth hormone releasing peptide. Pentapeptide structure.
Half-Life
~2 hr
Short half-life allows precise timing around sleep and training.
Selectivity
High
Highly selective GH release with minimal effect on cortisol or prolactin.
Common Stack
+CJC
Often combined with CJC-1295 for synergistic GH pulse amplification.

// How It Works

Mechanism of Action

01
Ghrelin Receptor Binding
Ipamorelin binds to the ghrelin receptor (GHSR-1a) in the pituitary gland, mimicking the action of ghrelin without its appetite-stimulating side effects at standard doses.
02
Selective GH Pulse
Triggers a clean pulse of growth hormone from the anterior pituitary. Unlike GHRP-2 and GHRP-6, Ipamorelin does not significantly elevate cortisol or prolactin — a key differentiator.
03
IGF-1 Upregulation
Elevated GH levels stimulate hepatic IGF-1 production. IGF-1 mediates many of the downstream effects: protein synthesis, fat metabolism, and tissue repair.
04
Feedback Loop Preserved
Importantly, Ipamorelin works within the natural GH feedback system. It amplifies existing pulses rather than bypassing regulatory mechanisms, which is why it's considered a relatively safe research compound.
Ipamorelin GHSR-1a GH Release IGF-1 ↑ Recovery / Body Comp

// GHS Comparison

How Ipamorelin Compares

PeptideGH PotencyCortisol EffectProlactin EffectHunger EffectHalf-Life
IpamorelinModerate–HighMinimalMinimalMinimal~2 hr
GHRP-2HighModerateModerateModerate~1 hr
GHRP-6ModerateModerateLowStrong~2–3 hr
HexarelinVery HighModerateModerateLow~3 hr
MK-677HighLowLowStrong~24 hr

// Published Research

Key Research Findings

1998 · Raun et al.
Ipamorelin: A New Growth Hormone Releasing Peptide
The landmark characterization study demonstrating Ipamorelin's potent and selective GH-releasing properties with a favorable cortisol/prolactin profile compared to GHRP-6.
Selectivity
2001 · Ankersen et al.
Discovery of Novel GH Secretagogues
Confirmed dose-dependent GH stimulation and established the pentapeptide structure's role in receptor selectivity. Key basis for modern Ipamorelin research protocols.
Pharmacology
2009 · Clinical Review
Postoperative Ileus and GHS Applications
Ipamorelin was investigated for GI motility applications, demonstrating safety and tolerability in human subjects — one of the few human clinical datasets available.
Human Data
2014 · Svensson et al.
GHS Combinations and Synergy
Research on Ipamorelin combined with GHRH analogs showed synergistic amplification of GH pulses, laying the scientific groundwork for the now-common Ipamorelin/CJC-1295 stack.
Combinations
Selective.
Studied.
Understood.

Ipamorelin stands out among GHS compounds for its clean selectivity profile — meaningful GH stimulation with minimal interference with cortisol, prolactin, or appetite pathways. That profile makes it one of the most researched peptides in the secretagogue class.

PubMed Research →