Library / Growth hormone

Ipamorelin

Also known as NNC 26-0161

Failed trials

Synthetic pentapeptide that stimulates growth hormone release via the ghrelin receptor. A phase 2 trial for bowel function after surgery did not meet its primary endpoint and it was not developed further.

Not an approved medicine. Ipamorelin is not an approved medicine for this use in Australia or the United States. This page summarises published research for information only. It is not a recommendation to use Ipamorelin, and VialOwl does not sell or supply it.

Background

Synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) discovered by Novo Nordisk in Denmark and described in 1998 as the first selective growth hormone secretagogue. It was later tested for bowel recovery after surgery, where a phase 2 trial did not show benefit, and was not developed further.

How it is thought to work

Activates the ghrelin receptor to release growth hormone. In animal studies it did not raise ACTH or cortisol, unlike GHRP-2 and GHRP-6.

What is claimed, and the evidence

Claim	Evidence	Notes
Speeding bowel recovery after abdominal surgery	Human trials Not supported	Phase 2 randomised trial in 114 patients found no significant difference from placebo in time to tolerating a meal.
Selective growth hormone release without raising cortisol	Animal studies only	Shown in rats and pigs.
Bone growth	Animal studies only	Rat studies only.
Muscle gain, fat loss, better sleep and anti ageing	No published evidence	Common online claims, often in combination with CJC-1295; no controlled trials.

Side effects

Effect	How often	Notes
Adverse events similar to placebo in short hospital use	Common	Treatment emergent adverse events in 87.5% on ipamorelin versus 94.8% on placebo after surgery.
Serious adverse events including death with intravenous use Serious	Case reports	Noted by FDA from the published gastric motility study; causality not established.
Immune reactions from impurities or aggregation Serious	Frequency unknown	FDA concern for compounded injectable products.
Raised blood glucose, fluid retention, headache, flushing	Frequency unknown	Reported for GH secretagogues in reviews; ipamorelin specific rates unknown.

Warnings

FDA placed ipamorelin in a significant safety risk category for outsourcing facility compounding, citing immunogenicity and serious adverse events.
No human data for the doses and routes used by self administering users.
Unapproved products bought online or from compounders may be contaminated, non sterile, underdosed, overdosed or contain a different substance; the TGA warns their labelling may be inaccurate and it has received reports of severe allergic reactions and hospitalisations.

Regulatory status

Australia: Not included on the ARTG (unapproved). Schedule 4 in the Poisons Standard (listed by name), with Appendix D clause 5 possession controls.
United States: Not FDA approved. Not in 503A Category 2 as of May 2026 (previously listed); remains in 503B Category 2 (significant safety risks).

Sources

Also in Growth hormone

From the VialOwl library, reviewed 26 September 2026. For education and general information. It is not medical advice and not a recommendation to use Ipamorelin.