Ipamorelin | Peptide Research Hub

At a Glance

Ipamorelin is a synthetic pentapeptide growth hormone secretagogue that acts on the ghrelin (GHSR) receptor. Unlike other GH secretagogues like GHRP-6 or GHRP-2, ipamorelin is notable for its selectivity—it stimulates GH release without significantly affecting cortisol, ACTH, or prolactin levels.

Ipamorelin is often combined with GHRH analogs (like CJC-1295) for synergistic GH release.

⚠️ Research Status: Ipamorelin is not approved for human use. It was investigated for post-operative ileus and GH deficiency but has not received regulatory approval.

Mechanism of Action

Ghrelin Receptor Agonism

Binds to GHSR-1a (growth hormone secretagogue receptor)
Mimics ghrelin’s action on the pituitary
Stimulates GH release from somatotroph cells
Maintains physiological pulsatility

Selectivity Profile

Minimal cortisol increase: Unlike GHRP-6 and GHRP-2
Minimal prolactin increase: More selective than hexarelin
No significant appetite stimulation: Less than ghrelin or GHRP-6
Cleaner GH elevation with fewer off-target effects

Synergy with GHRH

GHRH (e.g., CJC-1295) + GHRP (e.g., Ipamorelin) = amplified GH release
Reflects natural physiology of dual hypothalamic signals
More effective than either alone

Evidence Summary

Growth Hormone Release (Human Studies)

Moderate Confidence RCT >10 Years

Clinical pharmacology studies showed:

Dose-dependent GH increases
Peak GH at 40-60 minutes post-injection
Minimal effect on cortisol/prolactin
Consistent responses over repeated dosing

Post-Operative Ileus (Phase 2-3)

Moderate Confidence RCT 3-10 Years

Ipamorelin was studied for accelerating bowel recovery after surgery:

Sponsored by Helsinn/Zealand Pharma
Mixed results in Phase 3 trials
Did not achieve regulatory approval for this indication
Demonstrated safety in hospitalized patients

Comparison to Other GHRPs

Moderate Confidence RCT >10 Years

Compound	GH Release	Cortisol	Prolactin	Appetite
Ipamorelin	+++	Minimal	Minimal	Minimal
GHRP-6	+++	++	+	+++
GHRP-2	++++	+	++	++
Hexarelin	++++	++	++	+

Safety & Unknowns

Adverse Events (Clinical Trials)

Event	Incidence
Injection site reactions	Common
Transient warmth/flushing	Occasional
Headache	Rare
Nausea	Rare

Generally well-tolerated in clinical studies
Short duration studies limit long-term conclusions

Unknowns

Long-term effects: No extended safety data
Cancer risk: Theoretical IGF-1 promotion concern (not studied)
Tachyphylaxis: Unknown if GH response diminishes over time
Cardiovascular effects: Not adequately studied

Regulatory Status

Region	Status
FDA	Not approved
EMA	Not approved
WADA	Prohibited (S2 – Peptide Hormones)

Key Studies

Year	Type	Finding
1998	Phase 1	Characterized dose-response and selectivity
2007	Phase 2	Post-operative ileus trials
2015	Review	Comparison to other GH secretagogues

GHRP-6: More potent but less selective
GHRP-2: High potency, increases cortisol
MK-677 (Ibutamoren): Oral non-peptide GHSR agonist
CJC-1295: GHRH analog often combined with ipamorelin

Changelog

Date	Change
2026-01-21	Initial dossier created