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What it is
A synthetic hexapeptide growth-hormone secretagogue, one of the earlier compounds in this class.
How it is proposed to work
Agonism at the growth-hormone secretagogue receptor. Unlike ipamorelin it also drives ACTH and prolactin release, so the hormonal response is broader than growth hormone alone.
Approved medical uses
Used as a diagnostic agent to assess growth-hormone secretory capacity in some jurisdictions, and that use is well evidenced: a single injection has been validated against the insulin tolerance test with favourable reproducibility, and compared head to head with it in the same patients. That is a single-administration diagnostic use and is not an approval for repeated therapeutic use. Regulatory standing for the diagnostic indication is not recorded in this dossier's jurisdictions and should be verified locally before it is described as approved anywhere.
Human research
Each entry states what the study found and, separately, what it cannot show.
- Controlled human trial2007n = 135
Validation of a single-injection GHRP-2 test against the insulin tolerance test in adult GH deficiency
Finding. Seventy-seven healthy subjects and 58 patients already confirmed GH-deficient by insulin tolerance test each received a single intravenous dose of GHRP-2 after an overnight fast, with blood sampled over the following two hours; the reported methods name no co-administered agent, so this is GHRP-2 on its own rather than a combined GHRH plus GHRP-2 test. Peak growth hormone occurred within 60 minutes in every subject and was far lower in patients than in the healthy group, with no difference between hypothalamic and pituitary disease. Repeated tests showed favourable reproducibility, and the authors derived a peak-growth-hormone cut-off for diagnosing GH deficiency that corresponds to the insulin tolerance test's own diagnostic threshold. Responses were unaffected by gender and slightly lower in elderly subjects and those with adiposity, which the authors report did not influence the diagnosis.
Limitation. A single administration in a diagnostic setting. It establishes GHRP-2 as a reliable and reproducible pituitary stimulus and says nothing about repeated administration or any therapeutic outcome. It is typed as a controlled human trial because the compound was administered by the investigators against a healthy comparison group and MEDLINE indexes the report as a controlled clinical trial and validation study — but group membership was fixed by each patient's prior insulin-tolerance-test result rather than allocated, and the report describes no blinding, so the control is a comparison group and not a randomised arm. It was conducted by the KP-102 Study Group, a collaborative group named for the compound's own development code, so developer involvement should be assumed rather than treated as independent.
- Controlled human trial2014n = 126
Forty-eight weeks of twice-daily intranasal GHRP-2 in short children with GH deficiency
Finding. One hundred and twenty-six prepubertal short children with GH deficiency — all of whom had shown serum GH rising to 9 ng/ml after a preliminary dose of the spray — were divided by a double-blind method into a placebo group and two GHRP-2 spray groups, dosed by body weight, and treated twice daily for 48 continuous weeks. Mean height SD score changed by 0.07 on placebo, 0.03 on the lower spray and 0.02 on the higher, with no significant difference among the three groups; blood IGF-I at baseline and after 48 weeks likewise showed no significant difference among the three groups. Forty-four placebo, 40 lower-dose and 40 higher-dose subjects completed the 48 weeks. The authors conclude that growth cannot be promoted by a transient increase in endogenous GH secretion, speculating that the area under the curve of serum GH produced by the spray is too small to produce biological effects.
Limitation. The largest and longest controlled human GHRP-2 trial located, and a genuine null on growth — but it is not a test of the claim this dossier states. It tests an intranasal spray in GH-deficient children rather than injected GHRP-2 in adults, and its endpoint is height SD score rather than muscle mass, body composition or recovery. GH release was a prerequisite for entry, set at serum GH rising to 9 ng/ml after a preliminary spray dose, yet growth did not follow, and the authors attribute that to insufficient GH exposure rather than to the receptor mechanism. The IGF-I result is a between-group comparison — no significant difference among the three groups — and must not be read as a within-group finding that IGF-I did not move over 48 weeks. The report describes a double-blind three-group design but does not state that allocation was randomised, and the abstract reports no safety or adverse-event outcome in either direction.
- Randomised controlled trial2006n = 19
Food intake after subcutaneous GHRP-2 infusion in lean and obese adults
Finding. Nineteen healthy, weight-stable subjects — ten lean and nine obese — received a double-blind randomised subcutaneous infusion of GHRP-2 at a higher rate, at a lower rate, or placebo for 270 minutes across three study visits, then ate from an ad libitum buffet lunch after taped instructions to eat as much as they wanted. Food intake rose dose-dependently, by 10.2 ± 3.9% on the lower infusion and 33.5 ± 5.8% on the higher, both against placebo. Obesity status did not influence the effect, all subjects had greater ratings of appetite before the meal on the higher infusion while fullness afterwards was similar, and serum GH rose dose-dependently in all subjects.
Limitation. A single infusion per visit in a laboratory setting with one test meal, so it demonstrates that the orexigenic effect is real and dose-dependent in humans but not that it persists or that it produces weight change. Small, and conducted in healthy weight-stable volunteers rather than in any wasting population where appetite stimulation would be the therapeutic goal. The longest human appetite observation in this dossier is a separate and uncontrolled study — twelve months of twice-daily oral GHRP-2 in ten GH-deficient children (Mericq et al. 2003, PMID 14513874, whose abstract names the sponsor outright as GPA-748, Wyeth-Ayerst) — in which seven of ten patients reported increased appetite confined to the first six months, BMI SD score moved from 0.21 to 0.25 without reaching significance, and the authors state their conclusion as conditional on the dose used. Its appetite outcome was patient-reported rather than measured intake; it is named here for context and is not the evidence this entry rests on.
- Human open-label2013n = 71
GHRP-2, arginine and insulin tolerance tests compared in the same pre-operative patients
Finding. Insulin tolerance, arginine and GHRP-2 stimulation tests were each performed in the same 71 pre-operative adults with pituitary tumours, aged 18 to 65; the GHRP-2 test is described as its own stimulation test, with no GHRH co-administration reported. Median peak growth hormone was significantly higher with the GHRP-2 test than with the insulin tolerance test, and higher again than with the arginine test. Against insulin-tolerance-test-defined severe adult GH deficiency (defined by a low peak growth hormone on that test), the GHRP-2 test gave 81.3% sensitivity and 94.5% specificity, compared with 93.8% and 85.5% for the arginine test. The authors call both acceptable alternatives to the insulin tolerance test while concluding that the diagnostic method and criterion should be reconsidered and adjusted to each population.
Limitation. A within-subject diagnostic comparison in patients already known to have pituitary tumours, not a general population, and conducted entirely in Japanese patients — the authors themselves say the criterion needs adjusting per population. All 71 patients underwent all three tests openly: the report describes no control group, no allocation and no blinding, and MEDLINE indexes it as a comparative study rather than a controlled trial, which is why this entry is typed open-label rather than controlled. Sensitivity of roughly four in five means the GHRP-2 test missed some cases the reference standard identified, which is the specific way it falls short of the insulin tolerance test rather than a general endorsement.
- Human open-label1998n = 9
Five days of daily subcutaneous GHRP-2 in healthy young men
Finding. Nine healthy young men received a daily subcutaneous injection of GHRP-2 for five days, with growth hormone profiled on days 1, 3 and 5. GH release was maintained on each day, but analysis of variance showed that significant response attenuation occurred (P < 0.01): mean peak GH fell progressively across the three days, as did the area under the growth-hormone curve. Mean serum IGF-I did not increase over the five days, although osteocalcin, another serum marker of GH activity in tissue, rose significantly.
Limitation. Nine healthy young men, single-arm, with no control group and no blinding described in the report, and five days is far shorter than any therapeutic course — it shows attenuation begins early on a once-daily schedule but cannot say where the response settles or whether another schedule behaves differently. Its value here is the dissociation it documents on this schedule: a real, repeated GH pulse that did not move IGF-I. That dissociation belongs to intermittent dosing and must not be generalised to the compound, because under continuous infusion IGF-I rises substantially (PMIDs 10372723, 9467533, 12030918). IGF-I is also a hormone level rather than a clinical outcome, measured in subjects whose muscle and body composition were never assessed.
Preclinical research
Animal and laboratory work. Useful for generating hypotheses; it cannot establish that something works in people.
No preclinical studies catalogued.
Potential safety concerns
- CautionPreliminary
Raises cortisol and prolactin alongside growth hormone, but the magnitude depends on how it is given and is easy to overstate in either direction. After a bolus the ACTH and cortisol response is consistent enough to have been used diagnostically. Under continuous infusion the authors describe the prolactin and cortisol rises as minimal beside a several-fold rise in growth hormone, and in one infusion study in critically ill patients no effect on serum cortisol was detected at all. The prolactin component rests on thinner evidence than the cortisol component, so non-selective should not be read as affecting everything. That repeated use therefore carries endocrine consequences beyond the intended one is an inference from single-dose and short-infusion data rather than something measured over a course of treatment.
- CautionInsufficient
Repeated-dose human data exist but do not amount to a safety dataset for the way it is used outside trials. Exposure has been studied at five days, at eight and twelve months in small numbers of growth-hormone-deficient children, and at forty-eight weeks double-blind in one hundred and twenty-six children — but these are mostly open-label, mostly paediatric, almost entirely in deficiency rather than in healthy adults using it for body composition, and carry no follow-up beyond roughly two years. One concrete laboratory signal travels with them: in a randomised five-day infusion trial in critically ill men, serum lactate and white cell count at day five were increased by GHRP-2 given alone and with TRH, though not when it was combined with TRH and GnRH.
- CautionPromising
Measurably increases food intake. A double-blind randomised placebo-controlled infusion raised ad libitum intake dose-dependently in lean and obese adults, an earlier infusion study in seven lean men found every subject ate more than on saline, and seven of ten children reported increased appetite during twelve months of oral dosing. Graded promising rather than established because the replication is not independent — all three reports share an author, two come from the same laboratory at small scale, and the third is uncontrolled with patient-reported rather than measured intake. Relevant to anyone using it during energy restriction, and to the dose-dependent nature of the effect.
Known interactions and contraindication considerations
- Cortisol elevation is relevant to anyone on corticosteroids or with adrenal pathology.
This list is not exhaustive and is not a substitute for a clinician reviewing your full medication history.
Regulatory status
Status is shown per jurisdiction and is accurate only as of the date stated. Where a compound is approved, the approval is bound to a specific formulation, manufacturer and indication — shown in the detail column.
| Jurisdiction | Standing | Detail |
|---|---|---|
United States FDA | Unapproved / investigational as of 1 Jun 2026 | No marketing authorisation. |
European Union EMA | Unapproved / investigational as of 1 Jun 2026 | No marketing authorisation. |
India CDSCO | Unapproved / investigational as of 1 Jun 2026 | Not approved for human use. Approval status for diagnostic use differs by country — verify locally. |
Japan PMDA / MHLW | Recommended as of 20 Sept 2026 | Recorded as recommended rather than approved, and the distinction is deliberate. What we can source is clinical standing: a peer-reviewed comparison states that the glucagon, arginine and GHRP-2 tests are recommended as alternatives to the insulin tolerance test in Japan for diagnosing adult growth-hormone deficiency. We have not verified a marketing authorisation against the Japanese register, so this row does not assert one. It covers single-administration diagnostic use only and is not a standing of any kind for repeated or therapeutic use. |
How it is being used
What the grey community actually runs, the reasoning they give, and our read on whether it follows from known biology. This is observation, not evidence, and not a recommendation.
Growth-hormone release
What is run
Pre-sleep and fasted, sometimes with additional daytime administrations.
Their mechanistic reasoning
That it produces a reliably larger growth-hormone pulse than ipamorelin, and that the cortisol and prolactin rise is small enough not to matter at the frequencies used.
Reported in the community’s own terms. Not our position.
Stacked with
- A GHRH analogue—Separate receptor, larger combined pulse.
Regimen shape
- Dose
- figure withheld
- Scale
- Microgram-scale
- Route
- Subcutaneous injection
- Frequency
- Daily, sometimes multiple times daily
- Timing
- Pre-sleep and fasted
- Duration
- Multi-week blocks
Our read
The first half is accurate — it is a more potent stimulus. The second half is the assumption doing the work, and it is untested. Repeated cortisol elevation is not obviously trivial in someone training hard, and nobody using it recreationally is measuring it. Ipamorelin exists specifically because this trade-off was considered worth avoiding.
What the community reports
The comparison is between how sure the community is and how much is actually known — evidence strength, not direction. A compound can have solid research that came out negative.
Displaced by ipamorelin in most current discussion. Where it is still used, the cortisol and prolactin trade-off is usually acknowledged rather than denied — the community here is fairly clear-eyed.
Commonly reported as helping
- A stronger perceived pulse than ipamorelin
- Appetite increase, useful to some in a surplus
Also reported, when it goes wrong
- Noticeable hunger, unwanted by most current users
- Reports of lethargy attributed to cortisol
- Water retention
Why these reports can mislead
Perceived pulse strength is not measurable by a user. Reports of it being 'stronger' describe subjective sensations — flushing, hunger, drowsiness — that reflect off-target effects at least as much as growth-hormone release.
Direct quotations are not published here yet. We will only carry verbatim reports once they are sourced, dated and checked — an unattributed quote is a testimonial, and testimonials are exactly what this section exists to replace.
Watch for, in this use specifically
- Cortisol and prolactin rise alongside growth hormone. If you are going to run it, measure them.
- No adequate human dataset for repeated long-term use.
Active clinical trials
No registered trials currently tracked for GHRP-2.
What remains unknown
The questions that would change our assessment if they were answered.
- Do the cortisol and prolactin effects matter clinically with repeated use?
- Would an adequately exposed regimen — continuous rather than intermittent — produce a body-composition result? IGF-I does rise under continuous infusion, and no one has carried that through to a muscle or body-composition endpoint.
- Is the appetite effect useful in a wasting population? It is the best-measured thing this compound does and has never been taken to a clinical endpoint.
References
- 1.Chihara K, Shimatsu A, Hizuka N, et al. A simple diagnostic test using GH-releasing peptide-2 in adult GH deficiency. Eur J Endocrinol. 2007.PMID 17609397doi
- 2.Tanaka T, Hasegawa Y, Yokoya S, Nishi Y. Increased Secretion of Endogenous GH after Treatment with an Intranasal GH-releasing Peptide-2 Spray Does Not Promote Growth in Short Children with GH Deficiency. Clin Pediatr Endocrinol. 2014.PMID 25374440doi
- 3.Laferrère B, Hart AB, Bowers CY. Obese subjects respond to the stimulatory effect of the ghrelin agonist growth hormone-releasing peptide-2 on food intake. Obesity (Silver Spring). 2006.PMID 16861611doi
- 4.Kinoshita Y, Tominaga A, Usui S, et al. The arginine and GHRP-2 tests as alternatives to the insulin tolerance test for the diagnosis of adult GH deficiency in Japanese patients: a comparison. Endocr J. 2013.PMID 23079545doi
- 5.Nijland EA, Strasburger CJ, Popp-Snijders C, et al. A five day treatment with daily subcutaneous injections of growth hormone-releasing peptide-2 causes response attenuation and does not stimulate insulin-like growth factor-I secretion in healthy young men. Eur J Endocrinol. 1998.PMID 9820615doi
Editorial change history
When we change a grade or a regulatory note, we log it here rather than editing quietly.
Dossier created.
Evidence grade changed from "preliminary" to "insufficient", and the human-research section filled with five cited studies in place of a single placeholder slot. Recorded rather than quietly amended, because the grade moved on a disputed reading of the literature and the reasoning needs to be auditable. The prior summary's framing that no therapeutic outcome trial exists was wrong: a 48-week double-blind placebo-controlled trial of intranasal GHRP-2 in 126 GH-deficient children (PMID 25374440) found no growth benefit over placebo and no between-group difference in IGF-I, and is now cited. That trial was considered as grounds for "tested-negative" and rejected, because it tested a different route, a different population and a growth endpoint rather than the muscle-recovery claim this dossier states, and because its authors attribute the null to insufficient GH exposure; no human study of GHRP-2 has measured muscle, body composition, strength or recovery at all, so grading it tested-negative would assert that the claim on this page was tested and failed when it has not been tested. A supporting argument that GHRP-2 raises GH without ever moving IGF-I was also rejected as false: that dissociation holds for the intermittent schedules tested but not for continuous exposure, where IGF-I rises substantially (PMIDs 10372723, 9467533, 12030918). Diagnostic validation (PMIDs 17609397, 23079545) is substantial and is now stated explicitly in approvedUses and evidenceSummary so the grade is not read as saying the compound is inert, and the unsourced claim that it is "used diagnostically in Japan" is replaced with what the cited paper supports plus a verify-locally caveat. The human food-intake evidence removed from the GHRP-6 dossier in the compound-conflation correction is placed here, where it was generated, and carried as a new safety signal graded "promising".
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