Ipamorelin - Study Reference

What it is

Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) that selectively activates the ghrelin receptor (GHS-R1a) to trigger pulsatile growth hormone (GH) release from the pituitary. It is mainly studied as a selective GH secretagogue and was tested in humans as a ghrelin mimetic to speed gut recovery after bowel surgery.

Dosing Reference from Studies

Mixed (human and animal)Human trial dose

1.6 ug/kg (swine ED50, ~0.0016 mg/kg, IV) to 1.6 mg/kg/day (rat, IV)

Dose in studies

Discussed in research communities 200-300 mcg/day (SC)

Reference from peptide forums and community discussions. Not a recommendation, not based on studies, and not an established human protocol.

No established human protocol

Dosing Reference from Studies Calculate syringe volume ->

How studies used it

Model: Rat (anaesthetized) and conscious swine; also rat pituitary cells in vitro
Studied for: GH-release pharmacology and receptor selectivity (the founding characterization study)
Dose: Rat GH-release ED50 about 80 nmol/kg (roughly 0.057 mg/kg at MW 711.9). Swine GH-release ED50 about 2.3 nmol/kg (roughly 0.0016 mg/kg, i.e. about 1.6 ug/kg). In vitro EC50 1.3 nmol/L
Dosing: Single intravenous bolus doses across a dose-response range
Route: Intravenous (in vivo); cell culture (in vitro)
Duration: Acute single-dose pharmacology

Effects measured: Dose-dependent GH release. In rats maximal GH about 1545 ng/mL; in swine maximal GH about 65 ng/mL. In vitro maximal GH release about 85 percent of reference. Highly selective: even at doses over 200-fold the GH ED50, ipamorelin did not raise ACTH or cortisol above GHRH-stimulated levels, and did not change FSH, LH, prolactin or TSH, unlike GHRP-6 and GHRP-2

Side effects: No adverse events reported in this study (selectivity was the main finding: no ACTH/cortisol/prolactin elevation)

Sources: Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-561.

Model: Human, adults undergoing open or laparoscopic small/large bowel resection
Studied for: Postoperative ileus (Phase 2 proof-of-concept randomized, double-blind, placebo-controlled trial); LARGELY NEGATIVE
Dose: 0.03 mg/kg per dose (already weight-based; mean/median patient body weight was not reported in the abstract, so no kg figure is needed beyond the per-kg dose itself)
Dosing: Twice daily
Route: Intravenous infusion
Duration: Postoperative day 1 through day 7 or hospital discharge

Effects measured: Did NOT meet its primary endpoint. Median time from first dose to tolerating a standardized solid meal was 25.3 h with ipamorelin vs 32.6 h with placebo, p = 0.15 (not statistically significant). 117 enrolled, 114 in safety and modified intent-to-treat analyses

Side effects: Treatment-emergent adverse events in 87.5 percent of ipamorelin patients vs 94.8 percent of placebo (no excess vs placebo); nausea and vomiting were among the events noted

Sources: Beck DE, Sweeney WB, McCarter MD. Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. Int J Colorectal Dis. 2014;29(12):1527-1534.

Model: Rat, male Sprague-Dawley (preclinical postoperative ileus model)
Studied for: Postoperative ileus (the animal model that supported the later human trial)
Dose: 0.01 to 1 mg/kg (range tested); effects at 0.1 to 1 mg/kg
Dosing: Single IV bolus, or repetitive dosing of four doses daily at 3-hour intervals over 2 days
Route: Intravenous bolus
Duration: Single dose, or 2 days for repetitive dosing (48 h monitoring)

Effects measured: A single 1 mg/kg dose shortened the time to first bowel movement after laparotomy with intestinal manipulation, without changing total stool output. Repetitive dosing (0.1 to 1 mg/kg) significantly increased cumulative fecal pellet output, food intake, and body weight gain

Side effects: No adverse events reported in this study

Sources: Venkova K, Mann W, Nelson R, Greenwood-Van Meerveld B. Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus. J Pharmacol Exp Ther. 2009;329(3):1110-1116.

Model: Rat, female Wistar, 8 months old
Studied for: Glucocorticoid-induced loss of bone formation (osteoporosis model)
Dose: 100 ug/kg (0.1 mg/kg) per dose
Dosing: Three times daily
Route: Subcutaneous injection
Duration: 3 months

Effects measured: Co-treatment with methylprednisolone (9 mg/kg/day): adding ipamorelin increased the periosteal bone formation rate about four-fold versus glucocorticoid alone, and improved maximum tetanic tension of calf muscles. Groups of 8 rats each (control, glucocorticoid, ipamorelin, combination)

Side effects: No adverse events reported in this study

Sources: Andersen NB, Malmlof K, Johansen PB, Andreassen TT, Ortoft G, Oxlund H. The growth hormone secretagogue ipamorelin counteracts glucocorticoid-induced decrease in bone formation of adult rats. Growth Horm IGF Res. 2001;11(5):266-272.

Model: Rat, female Wistar
Studied for: Whether glucocorticoid (methylprednisolone) blunts ipamorelin-driven GH release and catabolism
Dose: 0.4 mg/kg/day and 1.6 mg/kg/day
Dosing: Divided into four IV injections per day
Route: Intravenous
Duration: 8 to 10 days

Effects measured: Methylprednisolone (5.0 mg/kg) did not blunt the acute plasma GH response to ipamorelin or GHRH. When given with methylprednisolone, ipamorelin significantly reduced glucocorticoid-induced body weight loss and raised IGF-I levels

Side effects: No adverse events reported in this study

Sources: Malmlof K, Johansen PB, Haahr PM, Wilken M, Oxlund H. Methylprednisolone does not inhibit the release of growth hormone after intravenous injection of a novel growth hormone secretagogue in rats. Growth Horm IGF Res. 1999;9(6):445-450.

How solid the evidence is

Mixed and skewed toward animal data. The mechanistic and dose-response evidence is solid but mostly preclinical: the founding pharmacology (Raun 1998, PMID 9849822) is a clean rat-plus-swine study with per-kg ED50 values and clear selectivity (no ACTH/cortisol/prolactin rise), but it is acute single-dose and over 25 years old. The bone (PMID 11735244), catabolism/GH (PMID 10629165), and chronic somatotroph studies are all small single-lab rat studies (groups of about 8), several from the same Danish group (the developer Novo Nordisk lineage), so they share a sponsor-adjacent perspective and are not independently replicated at scale. The most important human data point is NEGATIVE: the Phase 2 postoperative ileus RCT (Beck 2014, PMID 25331030, 117 patients) did NOT meet its primary endpoint (time to tolerate a solid meal 25.3 h vs 32.6 h, p = 0.15). Safety in that human trial was reassuring (adverse events no higher than placebo), but efficacy was not demonstrated. There are NO published long-term human safety or efficacy trials for the muscle, bone, anti-aging, or body-composition uses ipamorelin is popularly marketed for; that marketing is an extrapolation from short rodent studies plus acute human GH-secretion pharmacology, not from controlled human outcome trials. Doses: the human trial dose (0.03 mg/kg) is inherently per-kg, and patient body weight was not reported. The rat/swine ED50 values were published in nmol/kg and converted here to mg/kg using ipamorelin MW 711.9; treat the converted figures as approximate.

Sources

Frequently asked questions

What is Ipamorelin?

Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) that selectively activates the ghrelin receptor (GHS-R1a) to trigger pulsatile growth hormone (GH) release from the pituitary. It is mainly studied as a selective GH secretagogue and was tested in humans as a ghrelin mimetic to speed gut recovery after bowel surgery.

Is Ipamorelin legal to buy in the EU?

Ipamorelin is sold strictly for laboratory research use. In the European Union it can be purchased as a research chemical, and it is not approved or intended for human or veterinary use. You are responsible for compliant handling in your country.

Where can I buy Ipamorelin in Europe?

You can buy Ipamorelin from PeptidesDirect, an EU-based shop that dispatches fast, tracked DHL parcels from within Europe. Every batch comes with a third-party Janoshik certificate of analysis (HPLC purity and mass-spectrometry identity), and selected batches also carry our own independent Liquilabs lab testing, all verifiable online before you buy.

Buy Ipamorelin (for research use)