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How Ipamorelin Works: Mechanism and Pharmacology

How Ipamorelin works: its target and mechanism as the sources state them, how long it acts, and what is still unknown.

Medical review pendingGHRP (ghrelin receptor agonist)Updated
Class
GHRP (ghrelin receptor agonist)
FDA status
Not approved
research chemical
Routes studied
intravenous infusion; intravenous infusion over 15 minutes; intravenous and intranasal
Half-life
2 hours terminal half-life
intravenous infusion (15 min), in people · Pharmaceutical research 1999, PMID 10496658

How long it acts

Half-life values from FDA labels and published studies, by route. Animal values are labelled and do not describe people.

Ipamorelin half-life by route
RouteHalf-lifeMeasured inSource
intravenous infusion (15 min)2 hours terminal half-lifePeoplePharmaceutical research 1999, PMID 10496658

Full detail, including drug-testing windows, is on the Ipamorelin half-life page.

The receptor it acts through

Pharmacological profiling with antagonists showed ipamorelin stimulates GH release via a GHRP-like receptor, like GHRP-6.[2]

The abstract of the human ileus trial rests its rationale on ghrelin-receptor stimulation having promotility effects in the gut.[3]

Ferret work tests ipamorelin and anamorelin as ghrelin mimetics against cisplatin-induced weight loss and feeding inhibition.[4]

How selective it is

In swine, none of the GH secretagogues tested affected FSH, LH, PRL or TSH, and ipamorelin did not raise ACTH or cortisol, even at doses more than 200-fold above the ED50 for GH release.[2]

Effects downstream of the receptor

In a rat model of postoperative ileus, the authors propose that ipamorelin speeds gastric emptying through a ghrelin receptor-mediated mechanism involving cholinergic excitatory neurons.[5]

In rats with colonic hypersensitivity, the anti-nociceptive effects of ipamorelin and a second mimetic were blocked by a ghrelin receptor antagonist.[6]

A growth-hormone time course in volunteers shows one episode of GH release followed by an exponential decline.[1]

What is not known

Drugs@FDA returned no ipamorelin product on 2026-10-02, so no label mechanism section exists to quote.[7]

A review describes the human evidence on this peptide class as ranging down to a complete absence of human studies.[8]

Related peptides

Ipamorelin vs TesamorelinGHRH analogIpamorelin vs SermorelinGHRH analogIpamorelin vs CJC-1295GHRH analog

Common questions

How long does Ipamorelin act in the body?

The half-life values we found are 2 hours terminal half-life (intravenous infusion (15 min)). A half-life is how long the amount in the body takes to fall by half; it is not the same as how long an effect lasts.

More on Ipamorelin

DosageDoses used in published studies, with the source for each.CalculatorVial, water and dose to syringe units.Side effectsWhat labels and studies report, and what is unknown.ResultsStudy outcomes and when they were measured.Legal statusFDA, compounding and WADA status with dates.BenefitsClaimed benefits next to what published studies measured.

Sources

  1. 1Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers.Pharmaceutical research · 1999PMID 10496658Accessed 2 Oct 2026
  2. 2Ipamorelin, the first selective growth hormone secretagogue.European journal of endocrinology · 1998PMID 9849822Accessed 2 Oct 2026
  3. 3Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients.International journal of colorectal disease · 2014PMID 25331030Accessed 2 Oct 2026
  4. 4The growth hormone secretagogue receptor 1a agonists, anamorelin and ipamorelin, inhibit cisplatin-induced weight loss in ferrets: Anamorelin also exhibits anti-emetic effects via a central mechanism.Physiology & behavior · 2024PMID 39043357Accessed 2 Oct 2026
  5. 5Efficacy of ipamorelin, a ghrelin mimetic, on gastric dysmotility in a rodent model of postoperative ileus.Journal of experimental pharmacology · 2012PMID 27186127Accessed 2 Oct 2026
  6. 6Attenuation of Visceral and Somatic Nociception by Ghrelin Mimetics.Journal of experimental pharmacology · 2020PMID 32801950Accessed 2 Oct 2026
  7. 7Drugs@FDA (openFDA) search: active ingredient "ipamorelin"U.S. Food and Drug Administration · 2026api.fda.govAccessed 2 Oct 2026
  8. 8The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration.Frontiers in endocrinology · 2026PMID 42395176Accessed 2 Oct 2026

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