Peptide Evidence Index

GHRP-2

Evidence last reviewed: September 2026

Quick answers

What is it?: GHRP-2 is a fully synthetic chain of six amino acids designed to mimic ghrelin and trigger a pulse of growth hormone release. Under the name pralmorelin, it has one narrow approval in Japan as a diagnostic test, but it is not approved as a treatment anywhere.
Why are people interested in it?: It's marketed online for muscle building, fat loss, and anti-aging, so people want to know whether its real, approved medical use as a diagnostic test says anything about those claims.
What has actually been studied?: Diagnostic studies in Japan giving a single injection and measuring the growth hormone spike that follows, in pituitary tumor patients, elderly patients, and adolescents, plus anti-doping detection research.
How strong is the evidence?: Early human data, but only for a single-injection diagnostic use. No trial has ever tested repeated dosing for muscle building, fat loss, or anti-aging.
What don't we know yet?: Whether repeated self-administration produces any lasting change in muscle, fat, or hormone levels, this has never been studied, and what long-term or repeated use does to the pituitary gland.
Where can I read the original research?: Sources at the bottom of this page: "Pralmorelin," Drugs in R&D 2004; Soga et al., Endocrine Journal 2019.

Plain-English overview

GHRP-2 is a fully synthetic six-amino-acid peptide, developed decades ago as part of a family of small peptides designed to mimic ghrelin's action on the pituitary gland and trigger a pulse of growth hormone release. Under the generic name pralmorelin, it holds one narrow, genuine medical approval in Japan, as a single-injection diagnostic reagent used to test how well a patient's pituitary gland can release growth hormone, not as a treatment for anything. It is not approved as a therapeutic anywhere, including the United States, where a development program for growth hormone deficiency was discontinued. It is prohibited at all times in competitive sport by the World Anti-Doping Agency, and anti-doping laboratories have identified it in confiscated black-market growth-promoting products.

What researchers are studying it for

diagnostic growth hormone stimulation testing (approved use, Japan)
evaluation of growth hormone deficiency in adults and adolescents

Current evidence level

Early human data

Regulatory status: Not an approved medicine. Evidence strength and approval are scored separately; approval is a regulatory decision about a specific use, not a measure of how much research exists.

Human research

No trial of GHRP-2 is registered on ClinicalTrials.gov. What exists instead is a body of published diagnostic-testing research, mostly out of Japan, where GHRP-2 (as pralmorelin) has been an approved diagnostic tool since the mid-2000s. A 2019 study in the Endocrine Journal gave a single GHRP-2 injection to 76 patients with non-functioning pituitary tumors before surgery, of whom 36 were classified with severe adult growth hormone deficiency, and found that the peak growth hormone response reflected the severity of hypopituitarism and predicted postoperative recovery of hormone secretion. A 2023 study in Growth Hormone & IGF Research applied the same single-injection test to 65 patients aged 65 and older with pituitary tumors and found the growth hormone response correlated with other measures of pituitary function. A 2024 retrospective study in the Journal of Pediatric Endocrinology and Metabolism examined the test in 23 adolescents and found unexpectedly high growth hormone peaks in some groups, suggesting the diagnostic cut-off used for adolescents may need revisiting. A 2004 regulatory history review describes a separate development track that once aimed at treating short stature in children, reaching Phase II testing in Japan, with US development by Wyeth discontinued around the same time; this review found no evidence a therapeutic approval for that use was ever granted. Separately, a 2020 anti-doping detection study gave a single 100-microgram intravenous dose of GHRP-2 to track how long it remains detectable in dried blood spots, evidence of a validated detection method and of real-world misuse, not of any benefit. No human trial has tested GHRP-2 for muscle growth, fat loss, or anti-aging, and none has given it repeatedly over days, weeks, or months to see what happens to body composition, strength, or hormone levels.

Animal and preclinical research

This review did not identify a distinct animal-efficacy literature for GHRP-2 separate from its human diagnostic-testing studies and the ghrelin-mimetic peptide series from which it was developed at Tulane University and Polygen.

Major findings

Giving GHRP-2 by injection reliably triggers a large, measurable spike in growth hormone in healthy people and a much smaller one in people with impaired pituitary function, a real, reproducible diagnostic finding.
In a 2019 study of 76 pituitary tumor patients, the peak growth hormone response to a single GHRP-2 injection reflected the severity of hypopituitarism and predicted recovery of hormone secretion after surgery.
A 2023 study in 65 patients aged 65 and older found the same single-injection test correlated with other measures of pituitary function in elderly patients.
A 2024 study in 23 adolescents found some patient groups had unexpectedly high growth hormone peaks, suggesting the diagnostic cut-off for adolescents may need revisiting.
A separate development program aimed at treating short stature in children reached Phase II testing in Japan as of a 2004 review, but no evidence was found that it was ever approved for that use, and US development was discontinued.
A 2020 anti-doping study validated a method to detect a single 100-microgram dose of GHRP-2 in dried blood spots up to four hours after injection.
No human trial has ever tested GHRP-2 for muscle growth, fat loss, or anti-aging, or given it repeatedly to see what happens with sustained use.

What has not been established

Whether repeated self-administration produces any lasting change in muscle, fat, or hormone levels; this has never been studied.
Whether the short-stature treatment program that reached Phase II in Japan was ever completed or formally abandoned.
What long-term or repeated use does to the pituitary gland, given that the only approved use is a single provocative test, not ongoing therapy.
Whether the single diagnostic dose has any relationship to the amounts used, unsupervised, by people buying it online.
What is actually in an unregulated vial sold as "GHRP-2" outside Japan's approved diagnostic product.

Important limitations

Every human study identified used a single injection for diagnostic purposes; none tested repeated dosing, which is how the compound is actually used by people buying it online.
All the diagnostic studies come from patient populations already being evaluated for pituitary problems, not healthy adults seeking muscle or fat-loss benefits.
No trial is registered on ClinicalTrials.gov, so there is no way to track ongoing or planned human research.
The anti-doping detection study, while methodologically solid, was designed to catch misuse, not to establish safety or benefit.
The short-stature therapeutic program's outcome (completed, abandoned, or ongoing) could not be confirmed from the available regulatory review.

Regulatory status

GHRP-2 is approved in Japan only, and only as a single-injection diagnostic reagent (marketed as pralmorelin) used to test pituitary growth hormone reserve, not as a treatment for anything. It is not approved as a therapeutic anywhere, including the United States, where development for growth hormone deficiency was discontinued. It is prohibited at all times in competitive sport by the World Anti-Doping Agency.

Primary research sources

Onuki T, Hiroaki T, Sawano K, et al., "Robust growth hormone responses to GH-releasing peptide 2 in adolescents": Journal of Pediatric Endocrinology & Metabolism 2024;37(8):730-733; PMID 38958228, DOI 10.1515/jpem-2024-0115
Teramoto S, Tahara S, Hattori Y, Kondo A, Morita A, "Assessment of anterior pituitary reserve capacity based on growth hormone response to growth hormone-releasing peptide-2 test in the elderly": Growth Hormone & IGF Research 2023;71:101545; PMID 37295337, DOI 10.1016/j.ghir.2023.101545
Soga A, Fukuda I, Kobayashi S, Tahara S, Morita A, Sugihara H, "Preoperative growth hormone (GH) peak values during a GH releasing peptide-2 test reflect the severity of hypopituitarism and the postoperative recovery of GH secretion in patients with non-functioning pituitary adenomas": Endocrine Journal 2019;67(2):167-175; PMID 31776295, DOI 10.1507/endocrj.EJ19-0288
"Pralmorelin: GHRP 2, GPA 748, growth hormone-releasing peptide 2, KP-102 D, KP-102 LN": Drugs in R&D 2004;5(4):236-239; PMID 15230633, DOI 10.2165/00126839-200405040-00011
Reverter-Branchat G, Segura J, Pozo OJ, "On the road of dried blood spot sampling for antidoping tests: Detection of GHRP-2 abuse": Drug Testing and Analysis 2020;13(3):510-522; PMID 33197153, DOI 10.1002/dta.2975

Full evidence entry (complete data, registry records, dosing evidence)

Early human data

Small or uncontrolled human studies only

At a glance

Also known as: Pralmorelin, GPA 748, KP-102
Class: Synthetic hexapeptide growth hormone secretagogue (GHRP family)
Derived from: A fully synthetic peptide from a series developed at Tulane University and Polygen to mimic ghrelin's action on the growth hormone secretagogue receptor; not a fragment of a natural hormone
Registered human trials: 0
…with published results: 0
Largest human trial: 76 patients with non-functioning pituitary adenomas (Japan, 2019), 36 of whom were classified with severe adult growth hormone deficiency — a single diagnostic injection to measure peak growth hormone response before pituitary surgery, not a treatment trial
Studied for: diagnostic growth hormone stimulation testing (approved use, Japan), evaluation of growth hormone deficiency in adults and adolescents
Dosing evidence: No human dose establishedThe only established human dosing is a single injection used in an approved Japanese diagnostic test for growth hormone deficiency; no dose has ever been studied for repeated self-administration, muscle building, fat loss, or anti-aging.
Regulatory status: Approved in Japan only, and only as a single-injection diagnostic reagent (marketed as pralmorelin) used to test pituitary growth hormone reserve — not as a treatment for anything. A separate development program aimed at treating short stature was underway in Japan as of a 2004 review but this review found no evidence it was ever approved for that use. GHRP-2 is not approved as a therapeutic anywhere, including the United States, where its development for GH deficiency was discontinued.
Anti-doping status: Prohibited at all times by the World Anti-Doping Agency, as a growth hormone-releasing peptide (GHRP class, S2); anti-doping laboratories have developed and validated methods specifically to detect its abuse

What it is

GHRP-2 is a fully synthetic chain of six amino acids, developed decades ago as one of a family of small peptides designed to mimic ghrelin's action on the pituitary gland and trigger a pulse of growth hormone release. Under the generic name pralmorelin, it holds one narrow, genuine medical approval — but not for anything it's marketed for online today.

It is prohibited in competitive sport at all times, and anti-doping laboratories have specifically identified it in confiscated black-market growth-promoting products.

What the studies actually found

The clearest, most repeated human finding is a diagnostic one: giving GHRP-2 by injection reliably triggers a large, measurable spike in growth hormone in healthy people, and a much smaller one in people whose pituitary gland can't produce growth hormone normally. That difference is real, reproducible, and is precisely why the test exists — clinicians in Japan have used it for years to evaluate patients before and after pituitary surgery, in the elderly, and in adolescents with suspected growth hormone deficiency.

That is a real, useful, and repeatedly confirmed finding. It is also a completely different question from whether GHRP-2 builds muscle, burns fat, or slows aging when someone injects it repeatedly outside a clinical setting — a question none of these studies asked.

What exists in humans

No trial of GHRP-2 is registered on ClinicalTrials.gov. What exists instead is a body of published diagnostic-testing research — mostly out of Japan, where GHRP-2 (as pralmorelin) has been an approved tool for evaluating pituitary growth hormone reserve since the mid-2000s. Recent examples include studies in 76 patients with pituitary tumors, 65 elderly patients, and 23 adolescents, all using the same design: a single injection, followed by blood draws to see how high growth hormone rises.

A separate development track once aimed at a genuine therapeutic use — treating short stature in children — was in Phase II testing in Japan as of a 2004 regulatory review, with US development by Wyeth discontinued around the same time. This review found no evidence that a therapeutic approval for that use was ever granted.

No human trial has tested GHRP-2 for muscle growth, fat loss, or anti-aging — the uses it is most commonly marketed for today. Separately, anti-doping researchers have built and validated laboratory methods specifically to catch GHRP-2 abuse in athletes, including a study that gave a single 100 microgram intravenous dose to track how long it remains detectable in blood — evidence of real-world misuse, not of any benefit.

What doses have been studied in humans

The only defined human dosing that exists is diagnostic: a single injection, given once, to provoke a short-lived spike in growth hormone that clinicians measure over the following hour or two. That regimen was designed to reveal whether someone's pituitary gland works, not to build muscle, burn fat, or produce any lasting effect — and it has never been studied as a repeated-dose regimen in healthy people.

No study has given GHRP-2 repeatedly over days, weeks, or months to see what happens to body composition, strength, sleep, or aging. Amounts described online for those purposes do not come from any published human study of repeated dosing. They typically trace back to the single diagnostic dose, or to animal research, scaled using conversions that estimate comparable exposure between species or contexts — not effectiveness or safety for a different purpose entirely.

What remains unknown

Whether repeated self-administration produces any lasting change in muscle, fat, or hormone levels — this has never been studied
Whether the short stature program that reached Phase II in Japan was ever completed or abandoned
What long-term or repeated use does to the pituitary gland, given that the approved use is a single provocative test, not ongoing therapy
Whether the diagnostic dose has any relationship to what's used, unsupervised, by people buying it online
What is actually in an unregulated vial sold as "GHRP-2" outside Japan's approved diagnostic product

Registry and study records

Robust growth hormone responses to GH-releasing peptide 2 in adolescents: PubMed · DOI: 10.1515/jpem-2024-0115 — n=23 adolescents, retrospective, diagnostic testing only
Assessment of anterior pituitary reserve capacity based on growth hormone response to growth hormone-releasing peptide-2 test in the elderly: PubMed · DOI: 10.1016/j.ghir.2023.101545 — n=65 patients aged 65+, diagnostic testing only
Preoperative growth hormone (GH) peak values during a GH releasing peptide-2 test reflect the severity of hypopituitarism...: PubMed · DOI: 10.1507/endocrj.EJ19-0288 — n=76 patients with pituitary tumors, Japan, diagnostic testing only
Pralmorelin: GHRP 2, GPA 748, growth hormone-releasing peptide 2, KP-102 D, KP-102 LN: PubMed · DOI: 10.2165/00126839-200405040-00011 — regulatory history review, Drugs in R&D, 2004
On the road of dried blood spot sampling for antidoping tests: Detection of GHRP-2 abuse: PubMed · DOI: 10.1002/dta.2975 — anti-doping detection method, includes a single-dose (100 µg IV) human administration study

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Evidence last reviewed: September 2026. Peptide Proof reports what studies found. We do not give medical advice, dosing guidance, or treatment recommendations.