Ipamorelin — Complete Research Guide (2026)

Last updated 2026-06-25

What is Ipamorelin?

Ipamorelin is a synthetic pentapeptide, a selective ghrelin-receptor (GHS-R1a) agonist / growth-hormone secretagogue first characterized by Raun and colleagues in 1998.

Its distinguishing feature is selectivity: it releases GH without meaningfully raising cortisol, ACTH or prolactin in preclinical work.

Human data are limited: a phase 2 randomized controlled trial for postoperative ileus (developed by Helsinn) and early pharmacokinetic-pharmacodynamic work exist, but most evidence is preclinical, and it is not an approved drug (research-use-only).

How does Ipamorelin work?

Ipamorelin binds the growth-hormone secretagogue receptor (GHS-R1a, the ghrelin receptor) to stimulate pituitary GH release and to promote gastrointestinal motility.

Its receptor selectivity is thought to explain the relatively clean GH release seen in animal studies compared with older GH-releasing peptides. [INFOGRAPHIC: Ipamorelin selective GH secretagogue]

What does the research say about Ipamorelin?

• Ipamorelin selectively releases growth hormone in preclinical models without meaningfully increasing cortisol, ACTH or prolactin, distinguishing it from earlier GH-releasing peptides. ^[1]
• In human volunteers ipamorelin produced a characterizable, dose-related growth-hormone response that was formally modeled pharmacokinetically and pharmacodynamically. ^[3]
• As a ghrelin-mimetic, ipamorelin advanced to a phase 2 randomized, double-blind, placebo-controlled human trial evaluating its effect on postoperative ileus after bowel resection. ^[2]

Clinical research & studies

The references below are the primary sources cited throughout this guide. Each links directly to PubMed or the regulator. Where evidence is preclinical (animal or in-vitro), that is stated rather than implied.

• [1] Ipamorelin, the first selective growth hormone secretagogue — Raun K et al., Eur J Endocrinol 1998. (preclinical (in-vitro / animal))
• [2] Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients — Beck DE et al., Int J Colorectal Dis 2014. (human RCT (phase 2, n=117))
• [3] Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers — Gobburu JV et al., Pharm Res 1999. (human PK/PD study)
• [4] Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats — Johansen PB et al., Growth Horm IGF Res 1999. (animal (rat))
• [5] The GH secretagogues ipamorelin and GH-releasing peptide-6 increase bone mineral content in adult female rats — Svensson J et al., J Endocrinol 2000. (animal (rat))
• [6] Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus — Venkova K et al., J Pharmacol Exp Ther 2009. (animal (rodent))

Dosing context

In the research and clinical-trial literature ipamorelin was administered intravenously in controlled protocols (for example, twice-daily dosing in the postoperative ileus trial) under supervision.

Any dosing figures reflect experimental or trial settings and are not treatment guidance for individuals.

Side effects & safety profile

Its selectivity for GH over ACTH/cortisol/prolactin in preclinical studies is often cited as a favorable feature, but this does not equal a proven human safety profile.

The phase 2 ileus trial included safety and intent-to-treat populations, yet the overall human safety evidence base remains small and short-term.

No reliable human half-life is asserted here; pharmacokinetic parameters were modeled in limited volunteer studies and are route-dependent.

Stacking & combinations

Ipamorelin has served as a chemical starting point for developing more potent GH secretagogues rather than being studied as a consumer stack.

Finding Ipamorelin vendors

User reviews

Frequently asked questions

References

1. [1] Ipamorelin, the first selective growth hormone secretagogue — Raun K et al., Eur J Endocrinol 1998. PMID: 9849822. View sourceStudy: preclinical (in-vitro / animal)Characterized ipamorelin as a selective GH secretagogue that releases GH without stimulating ACTH, cortisol or prolactin.
2. [2] Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients — Beck DE et al., Int J Colorectal Dis 2014. PMID: 25331030. View sourceStudy: human RCT (phase 2, n=117)A randomized, double-blind, placebo-controlled trial tested intravenous ipamorelin for postoperative ileus after bowel resection as proof of concept.
3. [3] Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers — Gobburu JV et al., Pharm Res 1999. PMID: 10496658. View sourceStudy: human PK/PD studyModeled ipamorelin's pharmacokinetics and the resulting GH response in human volunteers.
4. [4] Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats — Johansen PB et al., Growth Horm IGF Res 1999. PMID: 10373343. View sourceStudy: animal (rat)Ipamorelin increased longitudinal bone growth in rats.
5. [5] The GH secretagogues ipamorelin and GH-releasing peptide-6 increase bone mineral content in adult female rats — Svensson J et al., J Endocrinol 2000. PMID: 10828840. View sourceStudy: animal (rat)Ipamorelin increased bone mineral content in adult female rats.
6. [6] Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus — Venkova K et al., J Pharmacol Exp Ther 2009. PMID: 19289567. View sourceStudy: animal (rodent)Ipamorelin improved gastrointestinal transit in a rodent model of postoperative ileus.

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