Ipamorelin is a synthetic pentapeptide, sequence Aib-His-D-2-Nal-D-Phe-Lys-NH2, developed in the 1990s by Novo Nordisk under the code NNC 26-0161. It belongs to the growth hormone secretagogue (GHS) family and works by activating the same receptor as the natural hormone ghrelin.
The pitch behind it was selectivity. When researchers first characterized it, they tested it in rat pituitary cells, anesthetized rats, and conscious pigs, and found it triggered growth hormone release with a potency comparable to the older peptide GHRP-6. The difference was what it didn't do. GHRP-6 and GHRP-2 both push up ACTH and cortisol; ipamorelin did not raise either above the levels seen with GHRH alone, even at doses 200 times the amount needed to release GH. It also left FSH, LH, prolactin, and TSH untouched. The authors called it "the first GHRP-receptor agonist with a selectivity for GH release similar to that displayed by GHRH" (Raun et al., *European Journal of Endocrinology*, 1998).
How it works
Ipamorelin is a selective agonist of the growth hormone secretagogue receptor type 1a (GHS-R1a), the receptor ghrelin binds. That receptor sits mainly in the hypothalamus and pituitary. Activating it prompts the pituitary to release a pulse of stored growth hormone. Because it mimics ghrelin rather than overriding the body's signaling, it tends to preserve the normal pulsatile pattern of GH secretion rather than clamping levels high continuously (DrugBank: Ipamorelin, DB12370).
What the human research showed
This is where the story gets honest. Ipamorelin's GHS-R1a activity also stimulates gut motility, so it was taken into the clinic not as a bodybuilding aid but as a treatment for postoperative ileus, the temporary shutdown of the bowel after abdominal surgery. Helsinn Therapeutics ran the human trials.
A Phase 2, multicenter, double-blind, placebo-controlled study enrolled adults undergoing bowel resection and gave intravenous ipamorelin at 0.03 mg/kg twice daily versus placebo. The drug was well tolerated. It also didn't work: there were no significant differences between ipamorelin and placebo on the key or secondary efficacy measures (NCT00672074). Development for that indication was discontinued for lack of efficacy.
So the published human evidence on ipamorelin is essentially a clean safety signal attached to a failed efficacy result for one specific use. There is no approved human indication for it anywhere. It is sold today as a research peptide, not as a medicine.
Regulatory and anti-doping status
Ipamorelin has never been approved as a drug by the FDA or other major regulators. Materials sold under this name are research chemicals, labeled research use only and not for human consumption.
In sport, it is banned. The World Anti-Doping Agency lists growth hormone secretagogues and their mimetics under category S2 (peptide hormones, growth factors, related substances and mimetics), prohibited both in and out of competition (WADA Prohibited List). Anti-doping labs can detect ipamorelin and its metabolites in urine, and athletes have tested positive for it.
The buyer-quality angle
Because no regulator oversees ipamorelin as a medicine, nothing about a vial's contents is guaranteed by an approval process. What you get depends entirely on the seller. For research buyers comparing vendors, the things that matter are independent, third-party verification: a certificate of analysis (COA) tied to the specific lot, identity confirmation (typically mass spec), and purity by HPLC. peptideone aggregates published COAs and the vendor reputation signals it collects so those documents can be compared side by side. Treat a peptide with no lot-specific testing as an unknown.
Nothing here is medical, dosing, or efficacy advice. It is a summary of what the public record documents about a compound that remains unapproved for human use.