Ipamorelin

What it is

Ipamorelin is a synthetic five-amino-acid peptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) developed at Novo Nordisk in the 1990s as a growth hormone (GH) secretagogue [2]. It belongs to the growth hormone-releasing peptide family and was described by its developers as the first of that family to release GH selectively, without the rises in ACTH and cortisol seen with GHRP-2 and GHRP-6 in animal studies [2]. It later went into a phase 2 trial for postoperative ileus, a slowdown of the bowel after abdominal surgery, sponsored by Helsinn Therapeutics [3][4]. That program was discontinued [5]. Ipamorelin is not an FDA-approved drug in any form [7]. In compounding, it is often paired with CJC-1295 or sermorelin; FDA’s review notes that these combinations are marketed for uses that have not been studied [5].

How it works

Ipamorelin acts on the ghrelin receptor, the same receptor targeted by the stomach hormone ghrelin, which sits on pituitary cells and triggers GH release [2]. Blocking experiments in the original pharmacology work showed it stimulates GH through a GHRP-like receptor rather than the GHRH receptor, which is why it is grouped separately from GHRH analogues such as sermorelin and tesamorelin [2]. In eight healthy men at each of five infusion rates, ipamorelin produced a single episode of GH release that peaked at about 0.67 hours and then declined to negligible levels, at every dose tested [1]. In pigs it did not change FSH, LH, prolactin or TSH, and unlike GHRP-2 and GHRP-6 it did not raise ACTH or cortisol [2].

What the evidence shows

The human evidence is limited to a pharmacokinetic study in healthy men and one failed clinical trial. The 1999 study characterized how the drug moves through the body and how GH responds, but did not test any health outcome [1]. The phase 2 postoperative ileus trial enrolled 117 adults after bowel resection; median time to a first tolerated solid meal was 25.3 hours with ipamorelin and 32.6 hours with placebo, a difference that was not statistically significant, and no secondary endpoint differed either [3][4]. FDA’s 2024 review concluded it had not identified data supporting effectiveness for postoperative ileus or growth hormone deficiency and that development was reportedly discontinued after that trial [5]. No trial has tested ipamorelin for body composition, recovery or aging.

Regulatory status

Ipamorelin is not FDA-approved [7]. On September 29, 2023 FDA placed ipamorelin acetate in Category 2 of the 503A nominated list, the category for substances it says raise significant safety risks [8]. The 503A nomination was later withdrawn, so FDA now shows it as “nominated but withdrawn” for 503A [7]. On October 29, 2024 the Pharmacy Compounding Advisory Committee voted 0 yes, 12 no, 1 abstention against adding either ipamorelin (free base) or ipamorelin acetate to the 503A bulks list [6]. Ipamorelin acetate remains in 503B Category 2 on the list FDA updated March 21, 2025 [9], and it does not appear on the 503A list updated May 14, 2026 [10]. The Ohio Board of Pharmacy has acted against pharmacies compounding CJC/ipamorelin [11]. Verified September 24, 2026.

Half-life and what it means for a level curve

The reference half-life in STACK is 2 hours. It comes from a study of 40 healthy male volunteers who received ipamorelin as a 15-minute intravenous infusion; the terminal half-life was 2 hours, clearance 0.078 L/h/kg and steady-state volume of distribution 0.22 L/kg [1]. FDA’s 2024 review restates the same figures [5]. No human subcutaneous half-life has been published, so the intravenous value is used as the closest available estimate. In rats the half-life was about 27 minutes [5]. A 2-hour half-life means the estimated level is almost gone about 10 hours after a dose, and with once-daily dosing there is essentially no build-up from one day to the next; a level reaches about 97 percent of steady state after five half-lives, which here is 10 hours. STACK’s curve is an estimate from this published half-life, not a blood level.

Reported side effects

Human safety data come from two settings. In the pharmacokinetic study, the authors did not report any adverse events [5]. In the postoperative ileus trial, treatment-emergent adverse events occurred in 87.5 percent of ipamorelin patients and 94.8 percent of placebo patients, mostly related to surgery; the most common were nausea, vomiting and abdominal distention, and serious events such as infection and anastomotic leak occurred in 17.9 percent versus 15.5 percent [3][5]. FDA’s safety summary states that a published study identified serious adverse events including death when ipamorelin was given intravenously for gastric motility, and that compounded products may pose immunogenicity and impurity risks [7]. FDA found two non-serious adverse event reports for compounded ipamorelin products through September 30, 2023 [5].

Storage and handling

Because there is no FDA-approved ipamorelin product, there is no FDA label with storage instructions [7]. The nominated compounded form is a lyophilized powder for subcutaneous injection that is mixed with diluent before use [5]. Your pharmacy’s label governs: follow its instructions on refrigeration, light protection, the beyond-use date and how long a mixed vial may be kept. STACK’s reconstitution calculator turns the numbers on your vial and pharmacy label into a volume; it does not suggest a dose. If a combination product also contains CJC-1295 or sermorelin, the pharmacy label for that specific vial is the one to follow, and STACK can hold the vial as a single inventory item.

What STACK tracks for it

STACK records each ipamorelin dose as your prescriber wrote it, in mcg, with the date, time and injection site, and draws an estimated level curve from the 2-hour reference half-life, which you can override with your own estimate. Because the curve decays quickly, most people will see a series of short peaks rather than a rising baseline. You can also log sleep, weight, injection-site reactions and any side effect, and keep a vial inventory with the pharmacy’s beyond-use date. If your prescriber pairs it with CJC-1295 or sermorelin, each has its own page and its own curve, since their half-lives differ by orders of magnitude. STACK never suggests a dose or a schedule; it shows what you logged.

The reference half-life in STACK

STACK's simulator and the app use 2 h for Ipamorelin: about 2 h (terminal half-life after intravenous infusion). Measured in: healthy male volunteers, intravenous infusion over 15 minutes; no subcutaneous value published.

Estimate only. Modelled from the published half-life you selected and the doses you logged — not a measured blood level. Do not use it to make medication decisions.

Free tools for Ipamorelin

Read next

Sources

Every URL below was fetched and checked on 2026-09-24. Bracketed numbers in the text link here.

1. TrialPharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers (Gobburu et al., Pharm Res 1999)
2. OtherIpamorelin, the first selective growth hormone secretagogue (Raun et al., Eur J Endocrinol 1998)
3. TrialProspective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for postoperative ileus in bowel resection patients (Beck et al., Int J Colorectal Dis 2014)
4. TrialSafety and Efficacy of Ipamorelin for Management of Post-Operative Ileus (NCT00672074)
5. FDAFDA Briefing Document, Pharmacy Compounding Advisory Committee, October 29, 2024 (ipamorelin-related bulk drug substances)
6. FDAPharmacy Compounding Advisory Committee Meeting, October 29, 2024 — Final Summary Minutes
7. FDACertain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks — FDA
8. FDABulk Drug Substances Nominated for Use in Compounding Under Section 503A, updated September 29, 2023 (archived copy)
9. FDABulk Drug Substances Nominated for Use in Compounding Under Section 503B, updated March 21, 2025 — FDA
10. FDABulk Drug Substances Nominated for Use in Compounding Under Section 503A, updated May 14, 2026 — FDA
11. OtherPCAC backs majority of peptides in two-day public meeting — McDermott Will & Emery