# Ipamorelin: The Selective Growth-Hormone Pulse, Read From the Studies > Ipamorelin is the first selective growth hormone secretagogue — it triggers a clean GH pulse without raising cortisol or prolactin. A cited, plain-English digest of the published research. The first selective growth hormone secretagogue, read straight from the literature: the GH-axis mechanism, the human pharmacokinetics, the one failed trial, and what people report — each claim pinned to the study that measured it. ## Start here Ipamorelin is a tiny lab-made peptide — five amino acids — that tells your pituitary gland to release a short burst of growth hormone (GH). GH is the body's own signal for growth and repair. What makes ipamorelin stand out is how *clean* that signal is: it raises GH without also raising cortisol (a stress hormone) or prolactin (a hormone tied to milk production), which older peptides in its family always did [1]. Researchers built it in the 1990s and tested it in animals and a little in people. In the one published human trial — for slow bowel recovery after surgery — it did not work better than a dummy injection [3]. It has never been approved as a medicine, anywhere. People in research-use communities report better sleep and faster recovery; what they report, including the downsides, is on [the effects page](/effects) and is anecdotal, not proof. This site is a reading desk for the published science. It sells nothing, links to no seller, and gives no dosing or medical advice. ## What the ipamorelin research has actually shown Ipamorelin (sequence Aib-His-D-2-Nal-D-Phe-Lys-NH2) is the first growth hormone secretagogue (a compound that prompts the pituitary to secrete GH) shown to be truly *selective* — it releases GH potently while leaving the stress and reproductive hormones untouched [1]. In its founding 1998 characterization it released GH from rat pituitary cells and in conscious swine with an ED50 (the dose producing half the maximum effect) of 2.3 nmol/kg, comparable to the older peptide GHRP-6, yet it did not push cortisol above baseline even at doses more than 200 times the GH ED50 [1]. That selectivity is the whole reason the compound exists. The mechanism runs through one receptor. Ipamorelin docks onto the GHS-R1a receptor — the same receptor the hunger hormone ghrelin uses — on the GH-producing cells of the pituitary, opening a calcium signal that fires a GH pulse [1]. Because that pathway is separate from the one GHRH (growth-hormone-releasing hormone) uses, pairing ipamorelin with a GHRH analog is the pharmacological logic behind the popular CJC-1295 + ipamorelin combination — two complementary levers on the same gland. Human data is thin but real. In healthy male volunteers, ipamorelin showed clean, dose-proportional pharmacokinetics with a terminal half-life of roughly 2 hours and a single GH pulse peaking about 40 minutes after dosing [2]. That is the kind of crisp, predictable behavior a forward-looking pharmacology wants — and it is most of what we know about ipamorelin in people. ## The GH-to-IGF-1 axis, and where the story gets honest Growth hormone does much of its downstream work through IGF-1 (insulin-like growth factor 1), a signal the liver makes in response to GH. In sustained protocols, a class cousin of ipamorelin — GHRP-2 — held IGF-1, IGFBP-3, and IGFBP-5 elevated across a 30-day infusion in older adults without the response fading [8]. That is the optimistic read of the GH axis: a stimulus that keeps working. The honest read sits right beside it. In short rodent ipamorelin studies, longitudinal bone growth rose dose-dependently — from 42 to 52 µm/day across the dose range — *without* a measurable rise in total IGF-1 [4], a reminder that the GH pulse and the IGF-1 axis don't always move together over short windows. And the single human efficacy trial that exists, in postoperative ileus, missed its primary endpoint [3]. Ipamorelin is what happens when a five-amino-acid peptide produces a beautifully selective signal in the lab — and then meets the harder bar of a controlled human outcome. Both halves of that are on this site. The full mechanism is in the [Ipamorelin research](/research); a plain walkthrough is in [what does ipamorelin peptide do](/how-it-works). ## What this site is This is an independent editorial digest. It reads the ipamorelin literature, leads with what was measured, cites every quantitative claim, and keeps the community's anecdotal reports clearly walled off from the controlled data. The word *order* in the domain is a position relative to the research — an ordering of the evidence — not a storefront. Nothing here is for sale, no dose is recommended, and no link points to a seller. For the reported upsides and downsides, see [Ipamorelin effects](/effects); for the full source list, see the [Ipamorelin references](/references). --- An optimistic, plain-English ordering of the ipamorelin record — the selective GH pulse logged where the studies confirm it, the cortisol and prolactin pathways left dark, the lone failed human trial kept in full view, and the community reports walled off as anecdote; a reading console pointed at the science, never a clinic, and nothing here dosed, prescribed, or sold.