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GHRP-2 vs GHRP-6: differences, evidence and safety

Updated September 25, 202612 min

GHRP-2 vs GHRP-6: differences, evidence and safety

Answer first

GHRP-2 and GHRP-6 are lab-made peptides of six building blocks that act on the ghrelin receptor and release growth hormone. Both also raise cortisol and prolactin. GHRP-2 is licensed in Japan, but only as a one-off diagnostic test. GHRP-6 is approved nowhere. No study comparing their effects in people directly could be found.

At a glance

AttributeGHRP-2GHRP-6
Substance classGrowth hormone axisGrowth hormone axis
Legal categoryPrescription medicineResearch chemical
Approval status by market
United StatesNot approved (2023-09-29)Not approved (2023-09-29)
European UnionNot approved (2026-09-10)Not approved (2026-09-10)
GermanyNot approved (2026-09-10)Not approved (2026-09-10)
United KingdomNot approved (2026-09-10)Not approved (2026-09-10)
AustraliaScheduled substance (2026-05-28)Scheduled substance (2026-05-28)
CanadaNot approved (2026-09-10)Not approved (2026-09-10)
SwitzerlandNot approved (2026-09-10)Not approved (2026-09-10)
WADA statusProhibited (S2.2.4, 2026)Prohibited (S2.2.4, 2026)
Development stageApprovedPhase 3
Strongest evidencePhase 2 randomised trialPhase 3 randomised trial
Registered trials (ClinicalTrials.gov)00
Sequence length6 amino acids6 amino acids
Molecular weight818 g/mol873 g/mol
Last verified2026-09-102026-09-10

How they work

Both peptides dock onto the receptor for the hunger hormone ghrelin, called GHS-R, and the pituitary gland answers with a burst of growth hormone [1], [2]. Neither copies the body's own releasing hormone GHRH.

GHRP-2

  • Its route runs mainly through the hypothalamus, the brain region above the pituitary [1]. The pituitary itself is essential: in rats whose pituitary had been removed, it did nothing at all [3].
  • In conscious rats it released more growth hormone than injected GHRH did, and in conscious dogs it worked where GHRH failed. The authors read this as lower sensitivity to the brake hormone somatostatin [3].
  • It works even when the GHRH receptor is broken. In eleven people carrying a disabling mutation of that receptor, growth hormone still rose to 4.5 times the starting level (p = 0.002) [4].
  • One of its six building blocks, 2-naphthylalanine, does not occur in proteins at all [5].

GHRP-6

  • It came first. Cyril Bowers and Frank Momany published it in 1984, its receptor was cloned in 1996, and ghrelin itself was isolated three years later [6], [2], [7].
  • It uses a receptor of its own. In five healthy men whose response to GHRH had been blunted by a six-hour GHRH infusion, the response to GHRP-6 survived [8].
  • Yet it needs GHRH in the background. In nine healthy men, blocking the GHRH receptor cut the peak from 33.8 ± 4.8 to 6.2 ± 1.8 micrograms per litre (p < 0.0001) [9].
  • Tissue-protecting effects are attributed to a second receptor, CD36. That work comes almost entirely from one research line in Havana and from animal models [10].

The key difference is therefore not the target. Both press the same button, and both come from the numbered synthesis series of the Bowers group at Tulane University [11], [7]. They differ in their building blocks, in which effects were measured in people, and in legal standing.

Both leave the blood quickly. GHRP-2 has an elimination half-life of 0.42 to 0.69 hours in healthy adult men [1]. GHRP-6 cleared in two phases in nine healthy men, with half-lives of 7.6 ± 1.9 minutes and then 2.5 ± 1.1 hours [12].

What the studies show

Head-to-head: both in the same experiment

Head-to-head, animal In conscious pigs, one research team compared GHRP-2, GHRP-6 and ipamorelin. GHRP-2 and GHRP-6 both raised the stress hormones ACTH and cortisol, while ipamorelin left them untouched [13].

For growth hormone, GHRP-6 was less potent but more effective than GHRP-2. In pharmacology, "less potent" means more substance is needed for a given effect, and "more effective" means a larger maximum response. The underlying figures are amounts per kilogram and are not repeated on this page [13].

Head-to-head, human detection study An anti-doping research group gave five peptides of this family through the nose, GHRP-2 and GHRP-6 among them. GHRP-6 turned up in urine largely unchanged for up to 23 hours, its fragments for only 12 hours. GHRP-2 lasted 47 hours, the longest window of the five [14].

Beyond these two, no study that compares the effects of GHRP-2 and GHRP-6 directly in people could be found in the published record reviewed for this page. The early comparative studies of the Tulane series, where GHRP-2 carried the code KP 102, report no results against GHRP-6 in the sources reviewed [11].

Growth hormone release

Human, single dose For GHRP-6, eighteen healthy men received three rising test levels into a vein, plus a dummy. Peak growth hormone climbed from 1.2 ± 0.3 on the dummy to 7.6 ± 2.5, 16.5 ± 4.1 and 68.7 ± 15.5 micrograms per litre [15].

Diagnostic accuracy study In 77 healthy people, GHRP-2 raised growth hormone to an average peak of 84.6 ± 60.9 micrograms per litre. In 58 patients with severe deficiency the peak was 1.36 ± 2.60 micrograms per litre (p < 0.001) [16].

Stress hormones and prolactin

Neither peptide is selective for growth hormone.

Human, single dose In six young adults, GHRP-2 raised ACTH and cortisol as much as hCRH, the natural hormone used in hospital to test the adrenal glands. Prolactin rose too, less than after TRH (p < 0.01). The authors called the effect "not fully specific" [17].

Human, single dose In the 18 men given GHRP-6, prolactin and cortisol roughly doubled at the highest test level. They did not move at the two lower ones [15]. After a nasal evening dose, ACTH showed a trend upwards in the first half of the night [18].

Appetite and food intake

A common claim holds that GHRP-6 causes hunger and GHRP-2 does not. The human data on GHRP-2 say otherwise [19], [20].

Controlled cross-over After an infusion of GHRP-2, seven lean healthy men ate 35.9 ± 10.9 per cent more than after saline (p = 0.008). Every one of them ate more [19].

Double-blind randomised In 19 people, ten lean and nine with obesity, food intake rose step-wise under GHRP-2. It went up by 10.2 ± 3.9 per cent at the lower level (p = 0.011) and by 33.5 ± 5.8 per cent at the higher. Obesity made no difference [20].

Open, uncontrolled Seven of ten children taking GHRP-2 by mouth for twelve months reported a markedly bigger appetite in the first six months. Their body mass index score did not shift significantly (0.21 ± 1.5 against 0.25 ± 1.5) [21].

Animal data For GHRP-6, the eating effect is documented only in rats, with the peptide injected straight into the brain ventricles. Eating rose in step with the amount given (p < 0.01), while growth hormone did not follow [22]. No human study of appetite after GHRP-6 could be found in the sources reviewed, nor any comparing the two peptides on hunger [22].

As a diagnostic test

Both peptides have been tested as a way to detect growth hormone deficiency in adults.

Diagnostic accuracy study In the GHRP-2 study above, sensitivity and specificity crossed between 15 and 20 micrograms per litre. Whether the deficiency arose in the hypothalamus or in the pituitary made no difference [16].

Diagnostic validation For GHRP-6, 49 adults with suspected pituitary disease and 20 healthy controls were tested against the insulin tolerance test. A cut-off of 3.5 micrograms per litre gave 80 per cent sensitivity at 95 per cent specificity. No side effects occurred [23].

Longer use and IGF-1

Controlled infusion study Seventeen healthy older adults received GHRP-2 as a continuous infusion under the skin for 30 days. Pulsatile growth hormone more than tripled on day 1 and stayed more than 1.8-fold higher on days 14 and 30 (p < 0.001). IGF-1 reached a raised plateau (p < 0.025) [24].

Open, uncontrolled In six children with growth hormone deficiency treated with GHRP-2 for eight months, night-time growth hormone rose but IGF-1 and IGFBP-3 did not [25]. Over 6 to 24 months of nasal use, growth speed rose from 3.7 ± 0.2 to 6.1 ± 0.3 centimetres a year. IGF-1 stayed flat [26].

Human, repeated dosing For GHRP-6, the longest human exposure lasted days, not months. After repeated nasal doses over about two days, IGF-1 rose from 94.5 ± 5.8 to 125.8 ± 6.0 micrograms per litre in six men [27]. A 34-hour infusion in nine young men lifted it from 252 ± 23 to 312 ± 23 micrograms per litre [28].

Seven women aged 65 to 82 took GHRP-6 by mouth for four days. That brought no significant IGF-1 rise, at 77.1 ± 8.4 against 84.1 ± 12.2 micrograms per litre [29].

Illness trials and missed endpoints

Randomised cross-over In adults with prolonged critical illness, GHRP-2 on its own did not lower urea production, and osteocalcin did not rise [30]. The study did not look at survival or recovery [30].

Phase 3 randomised For GHRP-6, the COURAGE-2 trial randomised 188 people with acute ischaemic stroke. It tested a fixed combination with the growth factor EGF against standard care, without blinding. Disability scores, the Barthel index and survival showed no difference at three or six months [31].

Because the trial tested a combination, the share of GHRP-6 in any effect cannot be separated out [31].

These results come from different populations, routes, designs and study lengths. The figures for GHRP-2 and GHRP-6 therefore cannot be set against each other. No human study of either peptide that measured muscle, body fat or strength could be found in the sources reviewed [24], [32].

Safety

The two safety records differ in kind. GHRP-2 has official Japanese product information, but it describes a single diagnostic injection in a fasted person lying down. GHRP-6 has no product information anywhere, so its record rests on hormone measurements, one dog study and one combination trial [1], [31].

GHRP-2, from the Japanese product information and the FDA:

  • A feeling of heat in 16.0 per cent. It is the only side effect given a figure. Low blood pressure, a rise in the liver enzyme ALT, drowsiness and a raised white cell count each occurred in 0.1 to 5 per cent [1].
  • Pregnancy is a contraindication. In people with a pituitary adenoma, bleeding into the gland (pituitary apoplexy) has been reported for related substances, and it can be life-threatening [1].
  • Reported serious events. The FDA names increased insulin requirement, death of critically ill study subjects, infection and pancreatitis, "though causality has not been established" [5].

GHRP-6, from the studies and the FDA:

  • No adverse effects were reported in 18 men at any test level or in 69 people during diagnostic testing. These were single doses [15], [23].
  • Slower heart rate in dogs. In beagles treated for 28 days, heart rate fell at every dose level. No organ damage was found [33].
  • Serious adverse events in the stroke trial hit 30 of the 95 treated patients and 48 of all 188 (odds ratio 1.92, 95 per cent confidence interval 0.981 to 3.767). None was judged treatment-related [31].
  • The FDA's concerns name "potential effect on cortisol and increase in blood glucose due to decreases in insulin sensitivity" [34].

Shared risks. On 29 September 2023 the FDA placed both peptides in category 2 of bulk substances that may present significant safety risks. For both, it cites immunogenicity risk from aggregation and peptide-related impurities [5], [34].

Thirteen American pharmacy-made injections containing GHRP-6 were recalled between 2013 and 2018, several of them also containing GHRP-2. Twelve lacked sterility assurance, and one contained the germ Bacillus circulans [35].

Grey-market material is unreliable for both. GHRP-2 was found undeclared in tablets sold openly as a food supplement [36]. Two laboratories found Gly-GHRP-6, a variant with an extra building block, in seized doping material [37], [38].

No study comparing the safety of the two could be found, so neither can be called safer.

Why this page lists no doses. GHRP-2 is a prescription medicine in Japan, where the amounts belong to the product label and the doctor giving the test [1]. GHRP-6 has no approved use, and its studies used widely differing amounts for entirely different questions [15], [12]. This page therefore reports what was measured without repeating the amounts.

GHRP-2, under its generic name pralmorelin, has been a prescription medicine in Japan since 22 October 2004, licensed only as a single diagnostic injection [39], [1]. GHRP-6 is approved nowhere; in Cuba it is the investigational product CIGB-500 [33], [40]. Neither is approved in the seven markets tracked here. Australia lists both as prescription-only, and possession without authority is illegal [41], [42]. Both are banned in sport at all times under S2.2.4 of the 2026 list, and German anti-doping law names both [43], [44]. Status: 10 September 2026.

GHRP-2

Status at a glance

MarketStatusDate
United StatesNot approved2023-09-29
European UnionNot approved2026-09-10
GermanyNot approved2026-09-10
United KingdomNot approved2026-09-10
AustraliaScheduled substance2026-05-28
CanadaNot approved2026-09-10
SwitzerlandNot approved2026-09-10
Development stage
Approved
Strongest evidence
Phase 2 randomised trial
WADA status
Prohibited (S2.2.4, 2026)
Last verified
2026-09-10
Version
1.0

This page lists no doses.

GHRP-6

Status at a glance

MarketStatusDate
United StatesNot approved2023-09-29
European UnionNot approved2026-09-10
GermanyNot approved2026-09-10
United KingdomNot approved2026-09-10
AustraliaScheduled substance2026-05-28
CanadaNot approved2026-09-10
SwitzerlandNot approved2026-09-10
Development stage
Phase 3
Strongest evidence
Phase 3 randomised trial
WADA status
Prohibited (S2.2.4, 2026)
Last verified
2026-09-10
Version
1.0

Used together?

The blend directory lists no product that combines GHRP-2 and GHRP-6. GHRP-2 appears there only in the CJC-1295 + GHRP-2 Blend, with the note that the mixture holds no approval. The full list is under blends.

No study of GHRP-2 and GHRP-6 given together could be found in the sources reviewed for this page. Both act on the same receptor, and no description of what the combination does or how safe it is could be found in the published record.

Several of the recalled American pharmacy-made injections did contain both peptides, together with sermorelin. They were withdrawn over sterility concerns [35].

Frequently asked questions

Which is better, GHRP-2 or GHRP-6?

Neither can be ranked, because no study comparing their effects in people could be found. GHRP-2 raised food intake by 35.9 ± 10.9 per cent in seven lean men and holds a Japanese licence as a diagnostic test. GHRP-6 was studied mainly for growth hormone release after single doses, and its one large trial missed its primary endpoint.

Is GHRP-2 or GHRP-6 safer?

No study comparing their safety could be found, so no ranking is possible. GHRP-2 has official side effect figures for one diagnostic injection, led by a feeling of heat in 16.0 per cent. GHRP-6 has no product information at all. The FDA lists both among bulk substances that may present significant safety risks.

What is the difference between GHRP-2 and GHRP-6?

Both are peptides of six building blocks that act on the ghrelin receptor. Their sequences differ, and GHRP-2 contains the unnatural building block 2-naphthylalanine. GHRP-2 has a generic name, pralmorelin, and a Japanese licence as a diagnostic. GHRP-6 is older, has no generic name and is approved nowhere.

Can GHRP-2 and GHRP-6 be taken together?

No study of the two given together could be found, so nothing is known about the effect or the safety of the combination. Both act on the same receptor. The blend directory lists no product containing both, although several recalled American pharmacy-made injections combined them with sermorelin.

Does GHRP-2 or GHRP-6 cause more hunger?

Human data on appetite could be found only for GHRP-2. Seven lean men ate 35.9 ± 10.9 per cent more than on placebo, and a double-blind study in 19 people found rises of 10.2 ± 3.9 and 33.5 ± 5.8 per cent. For GHRP-6 the eating effect is documented only in rats, and no study comparing the two on hunger could be found.

Do GHRP-2 and GHRP-6 raise cortisol and prolactin?

Yes, both do. In six young adults GHRP-2 raised ACTH and cortisol as much as hCRH, and prolactin rose too. GHRP-6 roughly doubled prolactin and cortisol at the highest test level in 18 men. In pigs, both raised ACTH and cortisol while ipamorelin did not.

Is GHRP-2 approved in Japan as a treatment?

No. Japan licensed GHRP-2 on 22 October 2004 as a diagnostic, given once into a vein to test for growth hormone deficiency. The attempt to develop it as a treatment stopped in phase 2. GHRP-6 has no approval in any country.

Are GHRP-2 and GHRP-6 banned in sport?

Yes, both at all times, in and out of competition. Section S2.2.4 of the 2026 Prohibited List names both. In a nasal study, GHRP-2 stayed detectable in urine for 47 hours and GHRP-6 for up to 23 hours.

How long do GHRP-2 and GHRP-6 stay in the body?

Not long. GHRP-2 has an elimination half-life of 0.42 to 0.69 hours in healthy adult men. GHRP-6 cleared in two phases in nine healthy men, with half-lives of 7.6 ± 1.9 minutes and 2.5 ± 1.1 hours.

Sources

Note on titles: where an original entry names a brand, it is replaced by a neutral description. This applies to entries 1 and 39. Publisher, date, codes and web address are unchanged.

  1. Pralmorelin dihydrochloride for injection — Japanese prescribing information. Kaken Pharmaceutical Co., Ltd., revision of July 2022, read in full on 10 September 2026 through KEGG MEDICUS, japic_code 00050479. Sections used: indication (4), administration (6, 7.1), contraindications (2.1, 9.5 to 9.7), side effects with frequencies (11.2), handling (14.1), other precautions (15.1), pharmacokinetics (16.1 to 16.5), clinical results (17.1.1, 17.1.2), pharmacology (18), physicochemical data (19.1) and storage (20). https://www.kegg.jp/medicus-bin/japic_med?japic_code=00050479
  2. Howard AD, Feighner SD, Cully DF, et al. (1996). A receptor in pituitary and hypothalamus that functions in growth hormone release. Science 273(5277):974-977. PMID 8688086. DOI 10.1126/science.273.5277.974
  3. Doi N, Hirotani C, Ukai K, Shimada O, Okuno T, Kurasaki S, Kiyofuji T, Ikegami R, Futamata M, Nakagawa T, Ase K, Chihara K (2004). Pharmacological characteristics of KP-102 (GHRP-2), a potent growth hormone-releasing peptide. Arzneimittelforschung 54(12):857-867. PMID 15646370. DOI 10.1055/s-0031-1297041. Conscious and anaesthetised rats, conscious dogs, cultured pituitary cells, and rats after removal of the pituitary or damage to the median eminence.
  4. Gondo RG, Aguiar-Oliveira MH, Hayashida CY, Toledo SP, Abelin N, Levine MA, Bowers CY, Souza AH, Pereira RM, Santos NL, Salvatori R (2001). Growth hormone-releasing peptide-2 stimulates GH secretion in GH-deficient patients with mutated GH-releasing hormone receptor. Journal of Clinical Endocrinology and Metabolism 86(7):3279-3283. PMID 11443201. DOI 10.1210/jcem.86.7.7694. Eleven people with a homozygous receptor mutation and eight controls.
  5. US Food and Drug Administration. Certain bulk drug substances for use in compounding that may present significant safety risks. Entry "Growth hormone releasing peptide-2 (GHRP-2) (for injectable and nasal routes of administration)", category 2, column 503B, dated 29 September 2023. Page content current as of 22 April 2026, read on 10 September 2026; the column was checked in the HTML source of the table row. Section 503B covers outsourcing facilities, not pharmacy compounding under 503A. https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
  6. Bowers CY, Momany FA, Reynolds GA, Hong A (1984). On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone. Endocrinology 114(5):1537-1545. PMID 6714155. DOI 10.1210/endo-114-5-1537
  7. Bowers CY (2012). History to the discovery of ghrelin. Methods in Enzymology 514:3-32. PMID 22975043. DOI 10.1016/B978-0-12-381272-8.00001-5
  8. Robinson BM, Friberg RD, Bowers CY, Barkan AL (1992). Acute growth hormone (GH) response to GH-releasing hexapeptide in humans is independent of endogenous GH-releasing hormone. Journal of Clinical Endocrinology and Metabolism 75(4):1121-1124. PMID 1400881. DOI 10.1210/jcem.75.4.1400881
  9. Pandya N, DeMott-Friberg R, Bowers CY, Barkan AL, Jaffe CA (1998). Growth hormone (GH)-releasing peptide-6 requires endogenous hypothalamic GH-releasing hormone for maximal GH stimulation. Journal of Clinical Endocrinology and Metabolism 83(4):1186-1189. PMID 9543138. DOI 10.1210/jcem.83.4.4711
  10. Berlanga-Acosta J, Abreu-Cruz A, Garcia Del Barco Herrera D, et al. (2017). Synthetic growth hormone-releasing peptides (GHRPs): a historical appraisal of the evidences supporting their cytoprotective effects. Clinical Medicine Insights: Cardiology 11:1179546817694558. PMID 28469491, PMCID PMC5392015. DOI 10.1177/1179546817694558
  11. Pralmorelin: GHRP 2, GPA 748, growth hormone-releasing peptide 2, KP-102 D, KP-102 LN (2004). Drugs in R&D 5(4):236-239. PMID 15230633. DOI 10.2165/00126839-200405040-00011. Company history, code assignment, the licence chain from Kaken to Wyeth and the discontinuation of the American development. The same entry names a German company as a co-developer and describes the series as three to five building blocks long, neither of which could be confirmed independently.
  12. Cabrales A, Gil J, Fernandez E, et al. (2013). Pharmacokinetic study of growth hormone-releasing peptide 6 (GHRP-6) in nine male healthy volunteers. European Journal of Pharmaceutical Sciences 48(1-2):40-46. PMID 23099431. DOI 10.1016/j.ejps.2012.10.006
  13. Raun K, Hansen BS, Johansen NL, Thøgersen H, Madsen K, Ankersen M, Andersen PH (1998). Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology 139(5):552-561. PMID 9849822. DOI 10.1530/eje.0.1390552. Conscious pigs; the study that measured the difference in selectivity between GHRP-2, GHRP-6 and ipamorelin.
  14. Semenistaya E, Zvereva I, Thomas A, Thevis M, Krotov G, Rodchenkov G (2015). Determination of growth hormone releasing peptides metabolites in human urine after nasal administration of GHRP-1, GHRP-2, GHRP-6, hexarelin and ipamorelin. Drug Testing and Analysis 7(10):919-925. PMID 25869809. DOI 10.1002/dta.1787. GHRP-2 had the longest detection window of the five, at 47 hours.
  15. Bowers CY, Reynolds GA, Durham D, Barrera CM, Pezzoli SS, Thorner MO (1990). Growth hormone (GH)-releasing peptide stimulates GH release in normal men and acts synergistically with GH-releasing hormone. Journal of Clinical Endocrinology and Metabolism 70(4):975-982. PMID 2108187. DOI 10.1210/jcem-70-4-975
  16. Chihara K, Shimatsu A, Hizuka N, Tanaka T, Seino Y, Kato Y (2007). A simple diagnostic test using GH-releasing peptide-2 in adult GH deficiency. European Journal of Endocrinology 157(1):19-27. PMID 17609397. DOI 10.1530/EJE-07-0066. Seventy-seven healthy people and 58 patients, with the cut-off derived against the insulin tolerance test. The accompanying commentary is PMID 17609398.
  17. Arvat E, di Vito L, Maccagno B, Broglio F, Boghen MF, Deghenghi R, Camanni F, Ghigo E (1997). Effects of GHRP-2 and hexarelin, two synthetic GH-releasing peptides, on GH, prolactin, ACTH and cortisol levels in man. Comparison with the effects of GHRH, TRH and hCRH. Peptides 18(6):885-891. PMID 9285939. DOI 10.1016/s0196-9781(97)00016-8. The source of the phrase "not fully specific". The abstract carries several typesetting errors in which half-sentences are missing, so individual figures cannot be taken from it with confidence; it also prints a shortened five-part sequence.
  18. Frieboes RM, Murck H, Antonijevic IA, Steiger A (1999). Effects of growth hormone-releasing peptide-6 on the nocturnal secretion of GH, ACTH and cortisol and on the sleep EEG in man: role of routes of administration. Journal of Neuroendocrinology 11(6):473-478. PMID 10336729. DOI 10.1046/j.1365-2826.1999.00364.x
  19. Laferrère B, Abraham C, Russell CD, Bowers CY (2005). Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men. Journal of Clinical Endocrinology and Metabolism 90(2):611-614. PMID 15699539. DOI 10.1210/jc.2004-1719. Seven lean men, infusion under the skin against saline, free-choice meal.
  20. Laferrère B, Hart AB, Bowers CY (2006). Obese subjects respond to the stimulatory effect of the ghrelin agonist growth hormone-releasing peptide-2 on food intake. Obesity (Silver Spring) 14(6):1056-1063. PMID 16861611. DOI 10.1038/oby.2006.121. Nineteen people, double-blind, randomised, two levels against placebo.
  21. Mericq V, Cassorla F, Bowers CY, Avila A, Gonen B, Merriam GR (2003). Changes in appetite and body weight in response to long-term oral administration of the ghrelin agonist GHRP-2 in growth hormone deficient children. Journal of Pediatric Endocrinology and Metabolism 16(7):981-985. PMID 14513874. DOI 10.1515/jpem.2003.16.7.981. Ten children over twelve months; the body mass index endpoint was missed.
  22. Locke W, Kirgis HD, Bowers CY, Abdoh AA (1995). Intracerebroventricular growth-hormone-releasing peptide-6 stimulates eating without affecting plasma growth hormone responses in rats. Life Sciences 56(16):1347-1352. PMID 8614257. DOI 10.1016/0024-3205(95)00087-9
  23. Alaioubi B, Mann K, Petersenn S (2009). Diagnosis of growth hormone deficiency in adults: provocative testing with GHRP6 in comparison to the insulin tolerance test. Hormone and Metabolic Research 41(3):238-243. PMID 19006049. DOI 10.1055/s-0028-1093350
  24. Bowers CY, Granda R, Mohan S, Kuipers J, Baylink D, Veldhuis JD (2004). Sustained elevation of pulsatile growth hormone secretion and IGF-I, IGFBP-3 and IGFBP-5 concentrations during 30-day continuous subcutaneous infusion of GH-releasing peptide-2 in older men and women. Journal of Clinical Endocrinology and Metabolism 89(5):2290-2300. PMID 15126555. DOI 10.1210/jc.2003-031799. With the earlier report by Bowers CY, Granda-Ayala R (2001), Endocrine 14(1):79-86, PMID 11322505.
  25. Mericq V, Cassorla F, Salazar T, Avila A, Iñiguez G, Bowers CY, Merriam GR (1998). Effects of eight months treatment with graded doses of a growth hormone (GH)-releasing peptide in GH-deficient children. Journal of Clinical Endocrinology and Metabolism 83(7):2355-2360. PMID 9661608. DOI 10.1210/jcem.83.7.4969. Six children, no control group; contains the authors' call for longer-acting formulations.
  26. Pihoker C, Badger TM, Reynolds GA, Bowers CY (1997). Treatment effects of intranasal growth hormone releasing peptide-2 in children with short stature. Journal of Endocrinology 155(1):79-86. PMID 9390009. DOI 10.1677/joe.0.1550079. Fifteen children, open and uncontrolled, half of them without a deficiency.
  27. Hayashi S, Okimura Y, Yagi H, et al. (1991). Intranasal administration of His-D-Trp-Ala-Trp-D-Phe-LysNH2 (growth hormone releasing peptide) increased plasma growth hormone and insulin-like growth factor-I levels in normal men. Endocrinologia Japonica 38(1):15-21. PMID 1915110. DOI 10.1507/endocrj1954.38.15
  28. Jaffe CA, Ho PJ, Demott-Friberg R, Bowers CY, Barkan AL (1993). Effects of a prolonged growth hormone (GH)-releasing peptide infusion on pulsatile GH secretion in normal men. Journal of Clinical Endocrinology and Metabolism 77(6):1641-1647. PMID 7903313. DOI 10.1210/jcem.77.6.7903313
  29. Ghigo E, Arvat E, Rizzi G, et al. (1994). Growth hormone-releasing activity of growth hormone-releasing peptide-6 is maintained after short-term oral pretreatment with the hexapeptide in normal aging. European Journal of Endocrinology 131(5):499-503. PMID 7952160. DOI 10.1530/eje.0.1310499
  30. Van den Berghe G, Baxter RC, Weekers F, Wouters P, Bowers CY, Iranmanesh A, Veldhuis JD, Bouillon R (2002). The combined administration of GH-releasing peptide-2 (GHRP-2), TRH and GnRH to men with prolonged critical illness evokes superior endocrine and metabolic effects compared to treatment with GHRP-2 alone. Clinical Endocrinology (Oxford) 56(5):655-669. PMID 12030918. DOI 10.1046/j.1365-2265.2002.01255.x. The largest of the intensive care studies; the peptide on its own left the metabolic markers unchanged.
  31. Hernandez-Bernal F, Subiros-Martinez N, Gutierrez-Ronquillo JH, et al., COURAGE Research Group (2026). Phase III open-label, randomized clinical trial of epidermal growth factor and growth hormone releasing hexapeptide in acute ischemic stroke. Journal of Clinical Neuroscience 152:112195. PMID 42462342. DOI 10.1016/j.jocn.2026.112195
  32. Dominikowski A, Rekos Z, Olejarz M, Szczepanek-Parulska E, Domin R, Ruchala M (2026). The emerging landscape of performance-enhancing peptides modulating the GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. Frontiers in Endocrinology 17:1822475. PMID 42395176, PMCID PMC13322892. DOI 10.3389/fendo.2026.1822475
  33. Castro J, Shaikh I, Silo S, et al. (2025). Subchronic safety assessment of CIGB-500 in beagle dog after repeated daily dose administration over 28 days. Regulatory Toxicology and Pharmacology 158:105798. PMID 40024561. DOI 10.1016/j.yrtph.2025.105798
  34. U.S. Food and Drug Administration. Certain bulk drug substances for use in compounding that may present significant safety risks. Category 2 table, row "Growth hormone releasing peptide-6 (GHRP-6)", section 503B, added 29 September 2023; page last modified 22 April 2026. Full text read 10 September 2026. https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
  35. openFDA drug enforcement API. Query for "GHRP-6" on 10 September 2026 returned 13 records, all read individually: D-1052-2014, D-0120 to D-0122-2016, D-0364-2016, D-0228-2017, D-0290 to D-0293-2017, D-0396 and D-0397-2017, D-0184-2019. https://api.fda.gov/drug/enforcement.json
  36. Thomas A, Kohler M, Mester J, Geyer H, Schänzer W, Petrou M, Thevis M (2010). Identification of the growth-hormone-releasing peptide-2 (GHRP-2) in a nutritional supplement. Drug Testing and Analysis 2(3):144-148. PMID 20878896. DOI 10.1002/dta.120. Identified and quantified in tablets sold openly as a supplement, where it was not declared. The Cologne laboratory's annual report on confiscated black-market products for 2009 is PMID 21204286.
  37. Krug O, Thomas A, Malerod-Fjeld H, et al. (2018). Analysis of new growth promoting black market products. Growth Hormone and IGF Research 41:1-6. PMID 29864719. DOI 10.1016/j.ghir.2018.05.001
  38. Gajda PM, Holm NB, Hoej LJ, et al. (2019). Glycine-modified growth hormone secretagogues identified in seized doping material. Drug Testing and Analysis 11(2):350-354. PMID 30136411. DOI 10.1002/dta.2489
  39. KEGG BRITE br08318, New drug approvals in Japan, retrieved 10 September 2026. The row dated 2004/10/22 for D02040, class 7223, pralmorelin dihydrochloride, Kaken Pharmaceutical, stands under drugs with new active ingredients, which fixes both the approval date and the licence holder.
  40. Registro Publico Cubano de Ensayos Clinicos (rpcec.sld.cu). Not reachable on 10 September 2026, with DNS resolution failing, so the registration numbers of the Cuban studies could not be verified and no Cuban marketing approval could be confirmed either way.
  41. Therapeutic Goods (Poisons Standard—June 2026) Instrument 2026, F2026L00633, registered 28 May 2026, full text read on 10 September 2026. Schedule 4 carries "# PRALMORELIN (GROWTH HORMONE RELEASING PEPTIDE-2 (GHRP-2))." and the class entry for the growth hormone releasing peptides. Appendix D, clause 5, headed "Poisons for which possession without authority is illegal", lists pralmorelin at item 30 and the class at item 19.
  42. Therapeutic Goods (Poisons Standard - June 2026) Instrument 2026, F2026L00633, registered 28 May 2026. Schedule 4 entries "# GROWTH HORMONE RELEASING PEPTIDES (GHRPs)." and "# GROWTH HORMONE RELEASING PEPTIDE-6 (GHRP-6)."; Appendix D, clause 5, items 19, 20 and 22. Text extract read 10 September 2026. https://www.legislation.gov.au/F2026L00633/asmade
  43. World Anti-Doping Agency, The 2026 Prohibited List, section S2.2.4. Full text read on 10 September 2026. The entry names the growth hormone releasing peptides individually, including "GHRP-2 (pralmorelin)", and lists the GHRH analogues separately in the same section. The 2025 list was checked in the same run and carries the same entry. https://www.wada-ama.org/en/prohibited-list
  44. Annex to section 2 subsection 3 of the German Anti-Doping Act (AntiDopG), published at BGBl. 2023 I No. 67, 1-5, section II.2.4, full text read on 10 September 2026. It names "GHRP-2, also known as pralmorelin" as the first example, followed by GHRP-2-Gly, GHRP-6, GHRP-6-Gly and hexarelin. Germany has no marketing authorisation for the substance.

Further reading

Last reviewed: September 2026

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