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Growth Hormone Research

Ipamorelin

Also referenced as: NNC 26-0161, growth hormone secretagogue

A selective growth hormone secretagogue often paired with GHRH analogues in community protocols.

Evidence grade
DPreclinical Research

Preclinical Research

Regulatory status
Not FDA Approved
Human data
Limited

No registered clinical trials identified

Last reviewed
September 1, 2026

Overview

Ipamorelin is a pentapeptide ghrelin receptor agonist developed to stimulate GH release with less effect on cortisol, prolactin and appetite than earlier secretagogues.

Clinical development targeted postoperative ileus rather than body composition, and did not lead to approval.

Why It's Being Studied

  • Selective GH release without broader hormonal disturbance.
  • Gastrointestinal motility after surgery.
  • Bone and body composition endpoints in animal models.

Mechanism of Action

In plain language

It acts on the receptor for the hunger hormone ghrelin in the pituitary, triggering a pulse of growth hormone.

Technical detail

Ipamorelin is a selective agonist at the growth hormone secretagogue receptor (GHS-R1a), stimulating somatotroph GH release through phospholipase C and calcium signalling. Selectivity claims rest on preclinical data showing minimal ACTH and prolactin release relative to GHRP-6 and GHRP-2.

Research Areas & Routes Studied

Areas studied
  • Growth hormone secretion
  • Gastrointestinal motility
  • Bone
Routes used in research
  • Subcutaneous injection (research)
  • Intravenous (clinical trials)

Evidence Summary

Preclinical characterisation is solid and a clinical programme in postoperative ileus was attempted, but no positive completed efficacy trials support current uses.

Human clinical evidence

  • Trials in postoperative ileus were conducted; the programme did not produce an approved indication.

Animal studies

  • Rodent studies characterised selective GH release and effects on bone and growth.

Anecdotal / community information

  • Widely used in combination protocols for sleep and recovery claims that have no controlled human support.

Reported Adverse Events in Research

  • Headache, flushing and injection-site reactions reported in research settings.
  • GH secretagogues can raise glucose and IGF-1; long-term consequences are uncharacterised.

Limitations of Current Evidence

  • No completed human efficacy evidence for body composition, recovery or sleep.
  • Community combination protocols are not clinical standards.

Research References

  • Animal study1998

    Ipamorelin, the first selective growth hormone secretagogue

    Raun K, et al. · European Journal of Endocrinology
    View Study
  • Regulatory document

    Registered ipamorelin trials

    View Clinical Trial
This page is an educational research summary. It is not medical advice, does not recommend human use, and does not provide individualised dosing. Many compounds discussed here are research use only and are not approved medicines.