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Growth hormone axis

Ipamorelin

A selective growth hormone secretagogue discontinued after its trials missed their endpoints — now sold for physique and recovery claims no trial ever tested.

L2PreclinicalExperimental / researchDiscontinued — efficacyVery low confidenceLast reviewed 2026-08-23
SC injection

Also known as: ghrelin receptor agonist, GHRP

Evidence passport

Last reviewed 2026-08-23

Evidence level
L2Preclinical
Confidence
Very low confidence
Human efficacy
22/100
Human safety
25/100
Regulatory status
Experimental / research
Development
Discontinued — efficacy
Routes
SC injection
Evidence base
Mostly preclinical
Furthest stage
Not established
Source curation
Source curation pending
Clinical maturity
Discontinued clinical development

Most of this evidence comes from animals and cells

The supporting research for Ipamorelin is predominantly preclinical (Level 1–2). That is a legitimate starting point for science and a poor basis for personal decisions. Human results are not simply a scaled-up version of mouse results.

Overview

Human evidence22/100
Preclinical evidence58/100
Human safety evidence25/100

Clinical maturity: Discontinued clinical development

Routes & formulations

Studied / approved routes

SC injection

Clinical trials used subcutaneous injection. No approved formulation exists; route-specific outcomes beyond hormonal effects were never established.

Route availability is not evidence of efficacy, and evidence from one route does not transfer to another. The Registry never provides dosing or sourcing information.

Peptide lifecycle

  1. Discovery

  2. Preclinical

  3. Phase I

  4. Phase II

  5. Phase III

  6. Approved

Discontinued — efficacyFurthest stage not established in our curated record

Clinical development was discontinued after trials in postoperative ileus did not meet their endpoints. The exact stage reached is not established in our curated record.

Why development stopped: Did not meet endpoints. Trials failed to show the benefit they were designed to detect.

Last documented development: 2009 — second phase 2 trial in postoperative ileus completed; results published in 2014 showed no benefit over placebo, and no further development is identified in the curated record.

What it is

A synthetic pentapeptide that mimics ghrelin at the growth hormone secretagogue receptor, selected for releasing GH with relatively little effect on cortisol or prolactin.

What people claim

  • Lean muscle gain
  • Fat loss
  • Better sleep and recovery
  • Gentle, side-effect-free GH boost

What the evidence actually says

It reliably raises growth hormone, and its selectivity profile is genuinely better than older secretagogues. But the clinical programme that would have proven benefit was abandoned after failing its endpoints in a different indication, and no trials support the physique and recovery claims made online.

Human evidence

  • Clinical trials in postoperative ileus that did not meet primary endpoints; development discontinued.
  • No controlled trials supporting muscle, fat-loss or recovery claims.

Preclinical evidence

  • Animal studies characterising selective GH release with limited cortisol and prolactin elevation.

Animal and cell findings are Level 1–2 evidence.

Mechanism and pathways

  • GHS-R1a agonism triggers pituitary GH release, complementary to GHRH signalling.
  • Relatively selective compared with earlier GHRPs.

Safety and unknowns

  • Ghrelin-receptor agonism can increase appetite — often the opposite of what buyers expect.
  • Injection-site reactions, headache and water retention reported.
  • No long-term human safety data for the way it is actually used.

Cancer relevance

Theoretical / mechanistic concern only

Indirect IGF-1 elevation carries the same theoretical proliferation concern as the rest of the GH axis. No human cancer outcome data exist for this compound.

Regulatory status

Not approved. Clinical development was discontinued after trials in postoperative ileus did not meet endpoints. Prohibited in sport.

Evidence grade

L2PreclinicalVery low confidence

Animal, organoid or tissue studies. Mice are not tiny humans.

What would change our rating?

  • Controlled trials with body-composition or functional endpoints.
  • Modern safety data for chronic administration.

References and sources

Source curation pending
  • To be curatedSources to be curated

Source hierarchy: regulatory documents and trial registries first, peer-reviewed work next, sponsor material flagged as non-independent. We never use supplier or clinic marketing as evidence, and where a verified source has not yet been curated we say so rather than inventing one.

Evidence change history

  1. 2026-06-20

    Baseline entry: discontinued clinical development recorded in the profile.

    L2PreclinicalBaseline entry
    Trials in postoperative ileus did not meet endpoints and development stopped. Physique claims have never been trialled.