100 to 300 mcg per injection under the skin, one to three times daily, most commonly 200 mcg
What was studied
100 mcg, one injection into a vein
The gap
Convention runs above the studied dose
How long it lasts
This entry gives no half life, in any species and by any route. The nearest thing in it to a timing figure is measured in days rather than hours, and it is about the response rather than the substance: across five days of one injection a day in nine healthy young men, the peak growth hormone fell from a mean of 83 micrograms per litre on day 1 to 59 on day 3 and 51 on day 5. That is a response fading, not a measurement of how long a dose stays in the body.
What it actually is
GHRP-2 is a lab built chain of six amino acids, the small building blocks that proteins are made from, and short chains like this are called peptides. It is an analogue of GHRP-6, meaning a molecule built to resemble it, rather than a form of ghrelin, the body's own hunger hormone. What makes it different from nearly everything else in this reference is that in one country it is a real approved medicine. In Japan it is sold as GHRP Kaken 100 for injection, generic name pralmorelin hydrochloride, by Kaken Pharmaceutical, for diagnosing whether the body is failing to put out growth hormone, marketed since February 2005 with the label last revised in July 2022. Read that approval closely, because it is narrow. The approved dose is one slow injection into a vein, given on an empty stomach, 100 micrograms from age 18, and 2 micrograms for every kilogram of body weight, capped at 100 micrograms, from age 4 to under 18. A single administration, as a test. It is the only growth hormone secretagogue in this reference with an approved medicinal product anywhere that I could find, and in the United States it is not approved at all.
What it is supposed to do
It makes the body release a pulse of its own growth hormone, and it does not stop at growth hormone. Arvat and colleagues in 1997 gave 1 and 2 micrograms for every kilogram of body weight into a vein to six normal young adults, and 2 micrograms per kilogram to six elderly subjects, and prolactin, the hormone behind milk production, along with adrenocorticotropic hormone, the pituitary signal that drives the stress hormone cortisol, and cortisol itself all rose alongside growth hormone, with the authors saying plainly that the compound is not fully specific. The part worth sitting with is what happens after that, or rather what does not. Growth hormone normally drives a second hormone made in the liver, insulin like growth factor 1, and that is the number people watch. Under repeated injections it did not move. In nine healthy young men given 100 micrograms under the skin once daily for five days, the peak growth hormone fell from a mean of 83 micrograms per litre on day 1 to 59 on day 3 and 51 on day 5, while mean insulin like growth factor 1 in the blood sat at 22, 25, 23, 25, 23 and 24 nanomoles per litre across days 1 to 6, which is no movement at all. That flatness held over eight months of escalating injections under the skin, 0.3 to 3.0 micrograms per kilogram per day, in six growth hormone deficient children who grew faster all the same, and over 18 to 24 months of dosing up the nose in children with short stature. It moved in two places and both were continuous rather than injected: five men and five women, older, with reduced growth hormone output and low insulin like growth factor 1, given 1 microgram per kilogram per hour by a pump under the skin for 30 days had both pulsing growth hormone and that blood marker up after 24 hours and up for the full 30 days, and in intensive care, twenty-six critically ill adults averaging 63 years were studied in a randomised crossover, twenty-two of them given a 1 microgram per kilogram injection into a vein followed by 1 microgram per kilogram per hour into a vein for 21 hours, with the blood marker up 61 percent within 24 hours. The article's own picture for that split is a bath with the plug out, where a trickle left running all month holds the level while a few hard bursts a day drain away in between, and it says outright that the picture is the author's rather than a published mechanism, and that no paper stating the pattern explicitly was found.
What people take it for
This entry does not survey what buyers say they are after. What it does is go looking for the outcomes such a buyer would want. Across roughly 250 PubMed records I found no human trial with body composition, lean mass, fat mass, muscle size, strength, athletic performance, recovery or injury healing as a measured outcome. The one study aimed at the people who actually buy this is a look back through the charts of men already on testosterone therapy who were given GHRP-2 alongside GHRP-6 and sermorelin, which reported insulin like growth factor 1 rising and measured only hormones in the blood. The effect best replicated in healthy adults is the one nobody sells it on, which is appetite: seven lean healthy men on a 270 minute drip under the skin at 1 microgram per kilogram per hour ate 35.9 percent more at a buffet meal than on salt water, and 19 subjects, ten lean and nine obese, on double blind drips under the skin ate 33.5 percent more at that same rate and 10.2 percent more at a tenth of it than on a dummy. The Japanese label prints a sensation of hunger as a listed reaction. Inside the approval there is only one use, a single test of whether the pituitary, the small gland at the base of the skull, is putting out growth hormone.
The dose question
What circulates
100 to 300 mcg per injection under the skin, one to three times daily, most commonly 200 mcg
What was studied
100 mcg, one injection into a vein
The Japanese label, marketed since February 2005: one slow injection into a vein, given fasting, for the diagnosis of growth hormone secretion deficiency. The nearest repeated dosing is Nijland, 100 mcg under the skin once daily for five days in nine healthy young men.
Above the studied dose
The approval covers a single administration as a test, one slow injection into a vein given fasting, and it says nothing about the second dose. What circulates is up to three injections a day under the skin, run in cycles. The bottom of that range is the same 100 mcg as the Japanese diagnostic dose and the Nijland protocol, and I could not establish any derivation for it, beyond noting that nobody appears to have reasoned from either. Across those five days of daily injections the peak growth hormone fell from a mean of 83 mcg/L to 51, and mean serum IGF-1 did not move at all. It moved under a 30 day pump and under a drip into a vein, not under an injection.
Reported because it is what people use. Nothing here recommends any amount.
How long it lasts
This entry gives no half life, in any species and by any route. The nearest thing in it to a timing figure is measured in days rather than hours, and it is about the response rather than the substance: across five days of one injection a day in nine healthy young men, the peak growth hormone fell from a mean of 83 micrograms per litre on day 1 to 59 on day 3 and 51 on day 5. That is a response fading, not a measurement of how long a dose stays in the body.
Route studied
Into a vein for the approved use, one slow injection given on an empty stomach, and into a vein again in Arvat 1997 at 1 and 2 micrograms per kilogram of body weight. Under the skin in the study that matches what people actually do, 100 micrograms once daily for five days in nine healthy young men. The two places insulin like growth factor 1 moved were both continuous rather than injected: a pump under the skin at 1 microgram per kilogram per hour for 30 days, and a drip into a vein at that same hourly rate for 21 hours in intensive care after a single injection into a vein. The appetite work used drips under the skin as well. In children, injections under the skin for eight months at 0.3 to 3.0 micrograms per kilogram per day, and dosing up the nose for 18 to 24 months. The 30 day pump paper also reports single doses of 0.1, 1 and 10 micrograms per kilogram, and its abstract describes the acute comparisons as going into a vein, specifying under the skin only for the 10 microgram per kilogram dose.
Route used
Injected under the skin at home, one to three times a day, taken on an empty stomach and run in cycles. That is a different route and a different frequency from the only approval I could find anywhere, which is one injection into a vein, given once, under supervision.
How to check you have the right molecule
This entry publishes no molecular weight and no sequence to hold a laboratory report against, so the checks it gives are on names and on paperwork. Start with the names, because there are at least six and it is the evidence they hide rather than the product: GHRP-2, pralmorelin, which is the international nonproprietary name, KP-102 with its formulation codes KP-102D and KP-102LN, GPA-748, and the Japanese trade name GHRP Kaken 100. Search only for GHRP-2 and you miss the entire Japanese regulatory file, so go and run the search for pralmorelin instead. On the powder itself, the one published finding this entry carries is that the Cologne analysts who found an extra glycine, one additional building block stuck on, in black market ipamorelin found it on GHRP-2 too, so an unexplained extra unit of weight on a certificate is the thing to look for. On paperwork, I found no registered study of GHRP-2 anywhere on ClinicalTrials.gov, so a trial number handed to you as support is worth going and checking yourself. Check the citations too, not just the numbers: one community dosing guide credits the fading response to "Raun et al., Growth Horm IGF Res (1998)" while linking PMID 9820615, which is Nijland in the European Journal of Endocrinology. Raun 1998 is the ipamorelin swine study, so a cycling protocol for this compound is being justified by a citation that, read literally, points at a pig experiment on a different molecule.
Three mistakes, and the first one is the whole compound. It is reading the Japanese approval as cover for the habit. Everywhere else in this reference I am reporting the absence of safety data, and here a regulator has a printed table with percentages on it, describing what one injection into a vein does when it is given fasting, under supervision, to find out whether a pituitary works. That is the entire approved use in the one country an approval could be found in, and it says nothing about the second dose. The second is the rise in insulin like growth factor 1 that gets quoted to buyers. It is real, and it came from a pump running for 30 days and a drip running in intensive care. Under the thing people actually do, an injection under the skin, that marker did not move over five days in healthy men, over eight months in growth hormone deficient children, or over 18 to 24 months up the nose. Nobody runs a pump. The third takes about five minutes to catch: the cycling advice in circulation is credited to a 1998 paper that is not the paper linked beside it, and the paper named is a swine study of ipamorelin, in which both GHRP-6 and GHRP-2 raised adrenocorticotropic hormone and cortisol while ipamorelin did not.
What is known about harm
This is the rare entry where a regulator has printed frequencies rather than me reporting an absence, and every one of those frequencies describes one injection into a vein, given fasting under supervision, rather than a repeated habit under the skin. Two automated readings of the package insert had disagreed about which reaction sits in which band, so the current insert was opened and the table read by hand. Three things sit at 5 percent or more: borborygmus, meaning rumbling and gurgling from the gut, a raised white cell count, and a sensation of heat, at 16.0 percent. At 0.1 to under 5 percent the label lists low blood pressure, nausea, stomach discomfort, a bloated abdomen, sleepiness, a runny nose, sweating, thirst, cold sweat, feeling generally unwell, unsteadiness, and a sensation of hunger. At unknown frequency it lists a rise in a liver enzyme called alanine aminotransferase, abdominal pain, dizziness, a bitter taste, back pain, headache, facial flushing, and shifts in the mix of white blood cell types. Note which one hunger is. It is a sensation of hunger rather than a decrease in appetite, and it is a quantified reaction rather than an unquantified one. What a single dose label cannot tell you is what the second dose does, or the hundredth. I found no published carcinogenicity, genotoxicity or repeat dose toxicology study, and the longest nonclinical dosing I found is six weeks, 10 micrograms under the skin twice a day in mice bred without growth hormone releasing hormone, the body's own signal to release growth hormone, where the peptide failed to restore growth and worsened the body composition abnormalities of growth hormone deficiency. In the United States it is not approved and it is not on the 503A bulks list, sitting in Category 3, nominated without adequate support, which means the Food and Drug Administration never evaluated it at all, and that placement was confirmed from an archived edition because fda.gov returned 404 to every automated attempt made on it. The World Anti-Doping Agency names it explicitly and by both names under S2.2.4 of the 2026 Prohibited List effective 1 January 2026, prohibited at all times and non-Specified, the tier carrying a four year default sanction.