Two separate signals control growth hormone release. This one imitates the second — and works with the body's feedback rather than around it.
Ipamorelin does not supply growth hormone. It asks your pituitary to release more of its own.
That distinction separates it from injected IGF-1, which bypasses the whole regulatory chain. Here the chain stays intact. That is the point of the compound, and also the limit on what it can do.
It is a pentapeptide — five amino acids — developed by Novo Nordisk under the code NNC 26-0161.
Your body uses two separate signals to release growth hormone. Knowing which is which explains almost everything about this class.
GHRH comes from the hypothalamus. It tells the pituitary to manufacture and release growth hormone. Think of it as the production order.
Ghrelin comes from the gut, and it is the same hormone tied to hunger. It does two things at the pituitary. It triggers release of hormone already stored there. And it suppresses somatostatin, the brake on the whole system. It opens the tap and releases the handbrake at once.
Ipamorelin imitates the second signal. It binds the ghrelin receptor, GHS-R1a, and the pituitary responds with a pulse of growth hormone.
That pulse matters. Levels peak around 40 minutes after administration and fall back to baseline, with a half-life near two hours. It is a spike, not a plateau — which is how the system naturally behaves. The largest natural pulse comes during deep sleep.
What is released then reaches the liver, and the liver turns it into IGF-1. That is the molecule doing the downstream work. Growth hormone carries the message. IGF-1 acts on it.
Stimulating the ghrelin receptor usually brings side effects with it. Earlier compounds in this class, GHRP-2 and GHRP-6, raise growth hormone. They also raise cortisol, ACTH and prolactin, and provoke considerable hunger.
The 1998 study that established ipamorelin's profile found none of that. It did not significantly raise ACTH, cortisol or prolactin, even at doses more than 200 times the amount needed to release growth hormone. There was no effect on FSH, LH or TSH either. The authors called it the first growth hormone secretagogue with selectivity close to natural GHRH.
That is a real and unusual result. It is worth noting it was established in swine and rat models, not in long-term human use.
Less than the compound's reputation implies.
Pharmacokinetics (1999, Pharmaceutical Research). Forty healthy male volunteers, dose escalation by intravenous injection. Half-life about two hours, growth hormone peaking near 40 minutes, dose-dependent response, well tolerated. This is the only published human pharmacokinetic study, and it measured hormone release rather than any clinical outcome.
Phase 2 trial (2014, International Journal of Colorectal Disease). This one deserves attention because it is the compound's only controlled clinical trial and it is rarely mentioned. 114 patients undergoing bowel resection received ipamorelin or placebo for post-operative ileus. It was well tolerated over seven days of twice-daily infusion — genuine human safety data.
It did not work. Time to tolerate solid food was 25.3 hours against 32.6 hours on placebo, not statistically significant. Development was discontinued after those results.
That failure does not mean the compound does nothing. It means it failed at that indication. But this is the only time ipamorelin has been tested against a clinical endpoint in people. It is also why no company is developing it.
Two rat studies are the most substantive efficacy findings available.
Adult female rats were given glucocorticoids, which cause bone loss. Ipamorelin offset the drop in bone formation, raising the rate of new bone on the outer surface up to fourfold against the steroid alone. A separate study found bone lengthening rise from about 42 to 52 micrometres a day, and the effect scaled with dose. Pituitary growth hormone content was unchanged. That last detail matters: the pituitary was not being depleted.
Both are animal studies. No human trial has examined bone.
The two signals are separate, so activating both produces more growth hormone than either alone. The production order and the release trigger arrive together. That is why ipamorelin is usually discussed alongside a GHRH analogue rather than on its own.
It also explains a rule worth understanding: combining two compounds from the same side achieves nothing. Two ghrelin agonists compete for one receptor. Two GHRH analogues compete for another. The synergy comes from using different pathways, not from stacking the same one.
Growth hormone release is suppressed by insulin. Eating, particularly carbohydrate, raises insulin, which is why growth-hormone-releasing compounds are studied and used in a fasted state. This is a real pharmacological interaction, not a ritual.
Here is where a widely sold protocol does not survive scrutiny.
Many clinics prescribe a "five days on, two days off" schedule. The reasoning is presumably to prevent receptor desensitisation.
The timescales do not match. Acute desensitisation after ghrelin receptor stimulation clears within about an hour. Chronic desensitisation is a much slower process. Research on the related compound hexarelin suggests it takes something like sixteen weeks of continuous exposure to develop, and about four weeks off to reverse.
A two-day break is far too long to matter for the first and far too short to address the second. It falls in the gap between the two phenomena it is supposedly managing.
Ipamorelin is not approved for any use anywhere. Its clinical development ended after a failed Phase 2. Human exposure in the published record runs to seven days.
What it does have is an unusually clean selectivity profile. It has a coherent mechanism that works with the body's own feedback rather than around it. And it has animal evidence on bone that gets less attention than it deserves.
What it lacks is any human trial demonstrating the outcomes people actually use it for.
This article explains published research and the rules around it. It carries no dose, no protocol, and no claim that any compound treats, cures or prevents a condition in anyone. Where the evidence is thin we say so. See our editorial standards.
Research-grade material, sold for laboratory research use. We link to a single supplier rather than a list, so you know exactly where the recommendation goes. Check the certificate of analysis against what a COA can and cannot show before you buy anything.
Commercial link. Nothing on this page is a dose, a protocol, or a claim that this compound treats or prevents any condition.
KLOW is GLOW plus 10 mg of KPV — that part is simple. The more useful fact is that both are, by mass, mostly copper peptide, and that is the ingredient whose injected form has no human trials.
An open study found sleep normalised in six of seven patients. The controlled study by the same investigator found weak effects and said so. The difference between them is a placebo arm.
It does not raise dopamine — it magnifies what other things do to it. That one property explains why caffeine feels stronger on it, and why MAO inhibitors are a hard contraindication.
