# Ipamorelin: The Ghrelin-Receptor Peptide, Read From the Studies > Ipamorelin is a selective GH secretagogue that hits the ghrelin receptor. The gut-motility data, the failed human trial, and the GH-pulse research — cited line by line. A zine-style read of the actual studies: the gut-motility data, the single GH pulse, the appetite question, and the one human efficacy trial that missed. Every number cited. ## The gist (read this first) Ipamorelin is a small lab-made peptide — five amino acids strung together. It works by flipping one switch in your body: the ghrelin receptor (the same receptor your natural hunger hormone uses). When it flips that switch on the pituitary gland, the gland releases a short pulse of growth hormone (GH). That's the whole mechanism in one line. The interesting part is what it *doesn't* do. Older peptides in its family also spiked stress hormones like cortisol. Ipamorelin mostly doesn't — that clean, single-purpose GH release is its claim to fame [1]. What people actually use it for is anti-aging, recovery, and sleep. What the *studies* have shown is narrower: it moves the gut along in rats with stalled bowels [11], it grows bone in rats [4], and in the one real human trial — for slow bowels after surgery — it didn't beat placebo [3]. It has never been approved as a medicine anywhere. "Medicinal" in this site's name is editorial framing, not a status. What people report — including the downsides — is on [the effects page](/effects). ## What the ipamorelin literature actually shows Ipamorelin (sequence Aib-His-D-2-Nal-D-Phe-Lys-NH2) is a synthetic pentapeptide — a chain of five amino acids — that selectively switches on the ghrelin receptor, formally the growth hormone secretagogue receptor type 1a (GHS-R1a). Hit that receptor on the pituitary and you get a discrete pulse of growth hormone. In the founding 1998 characterization, ipamorelin released GH potently in rat pituitary cells, rats, and conscious swine (swine ED50 = 2.3 nmol/kg, versus 3.9 nmol/kg for the older peptide GHRP-6) — but did **not** raise the stress hormones ACTH or cortisol, even at doses more than 200-fold above its GH-releasing dose [1]. That selectivity is the entire reason anyone cared about this molecule. The ghrelin receptor doesn't only live in the pituitary. It also sits on the nerves that run the gut, which is the thread this digest pulls hardest. In a rat model of postoperative ileus — the temporary bowel shutdown that follows abdominal surgery — repeated intravenous ipamorelin (0.1 or 1 mg/kg, four times daily) significantly increased cumulative fecal output, food intake, and body-weight gain over 48 hours versus vehicle, and a single dose shortened time to first bowel movement [11]. That gut-motility (prokinetic) signal is what carried ipamorelin into human trials. ## The one human trial — and why it matters more than the marketing Here is the sentence most vendor pages leave out. The only published Phase 2 randomized controlled trial of ipamorelin — 114 adults having bowel-resection surgery, given 0.03 mg/kg intravenously twice daily for up to 7 days — **missed its primary endpoint**. Median time to first tolerated meal was 25.3 hours with ipamorelin versus 32.6 hours with placebo, and the difference was not statistically significant (p=0.15) [3]. Treatment-emergent adverse events were actually slightly *lower* in the ipamorelin arm (87.5%) than placebo (94.8%), so the failure was about efficacy, not a safety blowup [3]. No Phase 3 trial followed. No regulator anywhere has approved ipamorelin for anything. When you read "clinically proven" in an ad, that claim is doing work the published [Ipamorelin research](/research) does not support. The honest version: strong rodent prokinetic data, a clean GH-selectivity profile, and one human efficacy trial that came up short. ## Pulse in, pulse out: the pharmacokinetics The human pharmacokinetics are unusually well characterized for a research peptide, because they were measured once and measured carefully. In healthy male volunteers given single 15-minute IV infusions (4.21 to 140.45 nmol/kg), ipamorelin showed dose-proportional kinetics with a terminal half-life of about 2 hours, clearance of 0.078 L/h/kg, and a steady-state volume of distribution of 0.22 L/kg [2]. The GH response was a single discrete pulse peaking around 40 minutes (0.67 h) after dosing [2]. That "one pulse, then gone" profile is the reason community protocols dose it repeatedly and pair it with longer-acting partners. It is also why the [appetite question](/appetite) is genuinely interesting: a ghrelin-receptor agonist that clears in a couple of hours has a narrow window in which to nudge hunger. The full dose-and-route record — strictly as studied in animals and the two human datasets — is on the [dosage page](/dosage), with no human protocol implied. ## What this site is This is an independent editorial digest of the peer-reviewed ipamorelin record, written for a curious adult, not a pharmacologist. It is not a clinic, not a pharmacy, and not a store. It does not sell ipamorelin, recommend a dose, or tell anyone to take anything. It reads the studies, leads with what they measured, cites every number, and is loud about the gaps — especially the missing long-term human safety data and the failed efficacy trial. If you want the community-reported [Ipamorelin effects](/effects) (clearly flagged as anecdote) or the full [Ipamorelin references](/references), both are one click away. --- A zine-style read of the ipamorelin record — the clean ghrelin-receptor GH pulse, the gut-motility data, and the one human trial that flopped, all cited and none of it dressed up; no clinic behind the page and nothing here dosed, stacked, or sold.