GHRP-2 is the outlier in its class, and not in the direction the market implies. Every other growth-hormone secretagogue sold for muscle — GHRP-6, ipamorelin, MK-677 — is an unapproved research compound with a thin or absent human record. GHRP-2 has a large, high-quality randomised literature and a marketing authorisation. It is also the compound on this site with the widest gap between how much has been studied and how little of it is about muscle.
This page counts the literature and classifies it. Figures from studies are reported as figures from studies; there is no usage guidance here, per our editorial standards.
What it is
A synthetic hexapeptide — six amino acids — that binds the growth hormone secretagogue receptor, the receptor for ghrelin. It contains no growth hormone and no growth-hormone-releasing hormone. It is a signal to the pituitary to release what the pituitary already has.
It travels under an unusual number of names, which matters for counting: GHRP-2, pralmorelin, KP-102 (and KP-102D, KP-102LN), GPA-748, and the spelled-out "growth hormone-releasing peptide-2". A search that misses any of them undercounts. The series was synthesised at Tulane University by Cyril Bowers, with development work in Germany at Polygen; Kaken Pharmaceutical acquired worldwide rights and sublicensed North America to Wyeth.
The count, and what the trials measured
Searched on 2026-09-20 across all six names: 243 papers, 151 of them tagged human, 43 carrying the randomised-controlled-trial publication type.
Forty-three randomised trials is a substantial literature — twice what GHRP-6 has. Read by title and abstract, they fall into three groups, and none of them is a performance group:
| What the randomised trials measure | Roughly |
|---|---|
| Growth-hormone pulse regulation: secretagogue synergy, feedback, waveform | The large majority |
| Sex steroids and ageing: oestradiol clamps, testosterone supplementation, pre- vs postmenopausal response | A substantial block within the above |
| Prolonged critical illness: pituitary reactivation with GHRP-2, TRH and GnRH infusions | 8 trials |
Every one of these is asking how the growth-hormone axis works, using GHRP-2 as an instrument for provoking it. That is a legitimate and rather elegant use of the compound. It is not a test of what it does to a body over weeks.
Searched specifically for a muscle, strength or lean-mass endpoint alongside the randomised-trial tag, the literature returns exactly one record. It is titled Effects of GHRP-2 and Cysteamine Administration on Growth Performance, Somatotropic Axis Hormone and Muscle Protein Deposition in Yaks (Bos grunniens) with Growth Retardation — fifteen one-year-old Qinghai high-plateau yaks, five per group, with myofibre diameter and area as outcomes. It found increases. It is a yak study with five animals per arm, and it is the strongest randomised muscle-tissue evidence this compound has anywhere.
Thirty-nine of 43 trials share one author
This is the finding of the page, and it is checkable in one query.
| Author | Randomised trials of GHRP-2 |
|---|---|
| Bowers CY | 39 of 43 |
| Veldhuis JD | 33 of 43 |
| Van den Berghe G | 8 of 43 |
Cyril Bowers is the researcher whose group made the compound. James Veldhuis runs the Mayo programme on growth-hormone pulse regulation. Greet Van den Berghe runs the Leuven critical-illness work. The randomised evidence base for GHRP-2 is, to a first approximation, one collaboration asking one family of questions for thirty years.
That is not a criticism of the work, which is careful and mechanistically deep — the oestradiol-clamp study on peptides for women comes from it, and is the only controlled evidence anywhere that the response to these compounds differs by menopausal status. It is a statement about what the literature covers. A body of work built by the people who developed the molecule, to characterise pituitary physiology, will answer pituitary questions thoroughly and body-composition questions not at all. Counting authors is a cheap check and it tells a reader how much independent replication sits behind a number.
The registry zero, and why this page does not publish it as an absence
An intervention search of ClinicalTrials.gov on 2026-09-20 returns zero registrations for GHRP-2 and zero for pralmorelin.
On most compounds this site covers, that zero is the story. Here it is a measurement artifact, and the reason is visible from the compound's own history: GHRP-2 is a licensed Japanese product, and Japanese clinical research is registered nationally, in jRCT and UMIN-CTR, neither of which is part of ClinicalTrials.gov. Both registries refused automated requests from our tooling on the date of writing, so this page does not state a Japanese count in either direction.
It does not need to. Forty-three randomised trials are published, which settles the only thing the registry zero might have been read to mean. The general rule is worth stating because it will recur: a registry census is a census of that registry, and the question to ask before quoting a zero is where this compound's studies would have been filed.
Approved — as a test, not a treatment
The 2004 Adis development profile records the position that still stands: pralmorelin was approved in Japan as a diagnostic agent for hypothalamo-pituitary function, held by Kaken. The logic is simple and it is the opposite of a performance claim. Healthy people release a large pulse of growth hormone in response; growth-hormone-deficient patients release much less; the original receiver-operating-characteristic analysis put the threshold at a peak of 15.0 micrograms per litre. One administration, one blood draw series, one diagnostic answer.
The same profile records phase II work in Japan for short stature and phase II work in the US for growth hormone deficiency with Wyeth, "discontinued". No regulator outside Japan lists it today.
The nearest thing to a human treatment record is the case report: one patient, a 20-year history of anorexia nervosa, intranasal GHRP-2 before every meal for a year, body weight from 21.1 kg to 27.8 kg over 14 months, with hunger, hypoglycaemia, fatigability and muscle strength described as improved and no obvious side effects reported. It is a single patient in an extreme clinical state, published because it was unusual.
Status: unapproved here, prohibited in sport
- FDA: GHRP-2 sits in category 2 of the published list of bulk drug substances nominated for compounding — substances the agency has identified as presenting significant safety risks. The list also holds GHRP-6, ibutamoren and ipamorelin, and this site's page on peptide therapy sets out what that classification does to a clinic's options.
- WADA: covered by S2.2.4, growth hormone releasing factors, prohibited at all times in and out of competition. See are peptides legal for athletes.
- Detection: GHRP-2 is among the best-characterised of these compounds in anti-doping laboratories. After a nasal dose in one volunteer, it and two metabolites were detectable in urine for up to 47 hours — the longest window measured in that study. The detail sits on peptides and drug testing, with the caution that one volunteer is a method-development result and no window on that page is a clearance time.
The honest summary
- 243 papers, 43 randomised trials, zero with a muscle, strength or performance endpoint in humans.
- 39 of the 43 randomised trials share an author with the person whose group synthesised the compound.
- The only randomised muscle-tissue result is in yaks, five per group.
- The only long human administration is one case report.
- It is approved in one country, as a diagnostic test, and its treatment development was discontinued.
- It is FDA category 2 and prohibited in sport at all times.
Set against the class ceiling this site has measured elsewhere — the growth-hormone secretagogues produce lean-mass changes around +1.4 kg with no strength gain, on best peptides for muscle growth — GHRP-2 is the compound in the group most likely to raise growth hormone reliably and the one least likely to have been tested for what that does.
Limits of this page
The counts are a title-and-abstract classification of PubMed on one date and a differently phrased query returns a slightly different set; the author counts are automated and count any authorship position. The Japanese registry position is stated as unverified because the registries would not serve our requests. Nothing here is advice about obtaining or using any compound, none of these substances is approved for human use outside the Japanese diagnostic indication described, and all of them are prohibited in tested sport.
Sources and dates
- Pralmorelin: GHRP 2, GPA 748, growth hormone-releasing peptide 2, KP-102 D, KP-102 LN. Drugs R D 2004;5(4):236–9 — PMID 15230633
- Hu R, Wang Z, Peng Q, et al. Effects of GHRP-2 and cysteamine administration on growth performance, somatotropic axis hormone and muscle protein deposition in yaks with growth retardation. PLoS One 2016;11(2):e0149461 — PMID 26894743
- Haruta I, Fuku Y, Kinoshita K, et al. One-year intranasal application of growth hormone releasing peptide-2 improves body weight and hypoglycemia in a severely emaciated anorexia nervosa patient. J Cachexia Sarcopenia Muscle 2015;6(3):237–41 — PMID 26401470
- Veldhuis JD, Bowers CY, et al. — the pituitary-regulation series; the oestradiol-clamp result is cited in full on peptides for women.
- PubMed, searched 2026-09-20: all six names, 243 records; with
"randomized controlled trial"[pt], 43; with a muscle, strength or lean-mass term added, 1. - ClinicalTrials.gov API v2,
query.intr, searched 2026-09-20: GHRP-2 → 0, pralmorelin → 0.