GHRP-2
The second-generation growth hormone-releasing peptide, sold in Japan under its drug name, pralmorelin, as a single-dose test for growth hormone deficiency. It reliably releases growth hormone, raises ACTH and cortisol and increases appetite; the plans to make it a treatment were never approved.
GHRP-2 is a synthetic six-residue peptide that activates the ghrelin receptor. One 100 µg intravenous dose is its approved use in Japan, and because it also releases ACTH and cortisol, Japanese endocrinologists use it to test the adrenal axis. In the US it is not approved, FDA's lists leave no compounding route for it, and WADA prohibits it.
What is it?
GHRP-2 is one of the synthetic growth hormone-releasing peptides developed by Cyril Bowers's group at Tulane with Polygen in Germany. It mimics ghrelin, the stomach hormone that binds the same growth hormone secretagogue receptor, and releases growth hormone from the pituitary; in the developers' 1993 human studies GHRP-6, GHRP-1 and GHRP-2 were, in that order, increasingly effective, and all three worked even by mouth. Its drug name is pralmorelin, and under that name Kaken Pharmaceutical markets it in Japan as GHRP Kaken 100, a single 100 µg intravenous dose used to test for growth hormone deficiency. Development as a treatment went further than that for a while: a 2004 profile describes phase II trials in Japan for short stature and in the US for growth hormone deficiency, the latter apparently discontinued. None became an approved therapy.
Its value as a test rests on how reliably it works. In the validation study, 77 healthy adults and 58 patients with severe deficiency received 100 µg intravenously after an overnight fast: growth hormone peaked within an hour in everyone, at 84.6 µg/L on average in the healthy group against 1.36 in patients, and a cut-off of 15 µg/L matched the standard insulin test's 3 µg/L, with good reproducibility and only mild effects of age and body fat. It works even when the hypothalamic signal is broken: in 11 people with a mutated GHRH receptor, GHRP-2 still raised growth hormone 4.5-fold, against 79-fold in controls, showing a direct action on the pituitary. It also combines with other stimuli. Arginine and GHRP-2 together released more growth hormone than either alone in men and women, and chronic GHRP-2 turned its combination with GHRH from additive to synergistic, with desensitisation depending on dose and frequency.
GHRP-2 does not release growth hormone alone. The same receptor sits on the cells that make ACTH, and Japanese groups now use this: in 47 patients with suspected pituitary or hypothalamic disease, a cortisol peak below 11.6 µg/dL after the GHRP-2 test identified adrenal insufficiency with 89.7% sensitivity and 88.9% specificity, comparable to the CRH test though not to insulin-induced hypoglycaemia. In rats it raised ACTH and corticosterone but not prolactin, and in mouse pituitary cells it stimulated ACTH secretion and synthesis directly. It also makes people hungry, as ghrelin does: seven lean men infused with GHRP-2 ate 35.9% more at a buffet meal than on saline, every one of them eating more.
The treatment studies are small and old. Fifteen children with short stature given intranasal GHRP-2 two or three times a day grew 6.1 cm a year at six months against 3.7 cm before, without any change in IGF-1; there was no control group. In 33 men with prolonged critical illness, randomised to placebo or GHRP-2 infusions with or without TRH and GnRH for five days, GHRP-2 restarted growth hormone secretion and normalised IGF-1 and its binding proteins, and only the three-hormone combination raised testosterone. None of this was followed by the larger trials a therapy needs.
Outside medicine its draw is the hope of a growth-promoting effect, the reason a 2010 doping paper gives for its prohibition in sport. That use rests on none of the studies above, which gave it intravenously, by infusion or by nasal spray under supervision. Its legal position in the US is closed on both compounding routes: FDA's 503A list puts it in Category 3 (nominated without adequate support), which the interim policy does not cover, and it has been in 503B Category 2 (significant safety risks) since September 29, 2023. In sport WADA names it outright, as GHRP-2 (pralmorelin), and doping laboratories can find it: after intravenous doses in ten men, both the unchanged peptide and its metabolite AA-3 were detected in urine, and a 2010 study showed GHRP-2 can mask the isoform test for growth hormone doping while itself remaining detectable.
Mechanism of Action
GHRP-2 activates the growth hormone secretagogue receptor, the receptor ghrelin uses. That receptor sits on the pituitary's growth-hormone cells, in the hypothalamus and on the cells that make ACTH, which is why one peptide releases growth hormone, cortisol and appetite at once.
Growth hormone from the pituitary
It acts on the pituitary directly: in people whose GHRH receptor does not work it still raised growth hormone, though far less than in controls, and it released growth hormone from cultured rat pituitary cells.
Works with GHRH and against somatostatin
Its effect needs the hypothalamus for full size and adds to GHRH, synergistically after chronic use; in rats and dogs it was less damped by somatostatin than GHRH was.
Same receptor as GHRP-6
In rat pituitary cells GHRP-2 and GHRP-6 desensitised cells to each other but not to GHRH, and a receptor antagonist blocked it: one receptor, two structures.
ACTH, cortisol and appetite
It releases ACTH and cortisol, the basis of the Japanese adrenal test, and like ghrelin it increases food intake.
Published Research
PubMed returns 261 records for GHRP-2, pralmorelin or KP-102. Our evidence set holds 53 papers; 30 name the peptide in their titles and have an abstract, and 18 are carded below: 12 studies in people, 1 review, 3 animal studies and 2 cell studies. Most human studies are single-dose physiology or diagnostic studies; none is a large trial of treatment. The developers' 1993 overview is listed in the references.
Chronic GHRP-2 and GHRH in younger and older adults
Normal men and women received GHRP-2, GHRH or both for 7 to 30 days. Either peptide given chronically converted the additive growth hormone response to the combination into a synergistic one, of different types. Whether the response desensitised during chronic dosing depended partly on dose and frequency.
Critical illness: GHRP-2, TRH and GnRH for five days, 33 men
Men with prolonged critical illness were randomised to placebo, GHRP-2 (1 µg/kg/h), GHRP-2 with TRH, or both with pulsatile GnRH. GHRP-2 reactivated growth hormone secretion and normalised IGF-1, IGFBP-3 and the acid-labile subunit; adding TRH restored thyroid hormones within a day, and only the three-hormone combination raised testosterone, by up to 312%.
Arginine, GHRP-2 and exercise, 9 men and 9 women
During 30 minutes of exercise with saline, arginine (30 g), GHRP-2 (1 µg/kg) or both, growth hormone release ranked arginine + GHRP-2 above GHRP-2 above arginine above saline, as at rest. Exercise boosted each agent's effect but blunted their synergy, and sex changed its relative size.
The GHRP-2 test for adrenal failure, 47 patients
Patients with suspected hypothalamic-pituitary disease had insulin tolerance, CRH and GHRP-2 tests. A peak cortisol below 11.6 µg/dL after GHRP-2 predicted secondary adrenal insufficiency with 89.7% sensitivity and 88.9% specificity. Its responses did not correlate with the CRH test, pointing to direct pituitary stimulation; it matched the CRH test but not the insulin test.
Validating the GHRP-2 test for adult growth hormone deficiency, 135 adults
Seventy-seven healthy adults and 58 patients with severe deficiency by the insulin tolerance test received 100 µg GHRP-2 intravenously after an overnight fast. Growth hormone peaked within 60 minutes in all, at 84.6 µg/L on average in the healthy group against 1.36 in patients. A 15 µg/L cut-off matched the insulin test's 3 µg/L; responses were reproducible and only slightly lower with age and adiposity.
Age and GHRP-2 efficacy under a leuprolide/testosterone clamp, 22 men
Young and older men had their sex steroids fixed with leuprolide and replacement testosterone, then received arginine with GHRH or GHRP-2. Young men released 1.3-fold more growth hormone to arginine/GHRP-2 than older men. IGF-1 was the main positive predictor of GHRP-2 efficacy, and abdominal visceral fat the main negative predictor of GHRH efficacy.
GHRP-2 increases food intake, 7 men
Lean healthy men received a subcutaneous GHRP-2 infusion (1 µg/kg/h) or saline for 270 minutes before a buffet meal. They ate 35.9% more with GHRP-2, every subject increasing intake, with no change in macronutrient mix, while growth hormone rose about 13-fold by area under the curve.
Detecting GHRP-2 and its metabolite in urine, 10 men
A liquid chromatography-tandem mass spectrometry method for doping control measured GHRP-2 and its metabolite AA-3 at 0.5 to 10 ng/mL with 84% to 101% recovery. After intravenous GHRP-2 in ten male volunteers, the unchanged peptide and AA-3 were detected in every urine sample.
GHRP-2 and the growth hormone doping test
In Japanese men, 100 µg of intravenous GHRP-2 raised recombinant and pituitary growth hormone isoform readings together, so it did not change the isoform ratio itself, but given after recombinant growth hormone it cut the elevated ratio to about 40%, masking the doping signal. GHRP-2 and its metabolite remained detectable in urine during that window.
The GHRP-2 test in TSH-secreting pituitary tumours, 5 patients
GHRP-2 does not raise TSH in normal people, but in two of five patients with TSH-producing adenomas it raised TSH by more than 50%, and in a third by 48%; after one tumour was fully removed the response disappeared. The authors propose the test alongside the TRH test.
Intranasal GHRP-2 in children with short stature, 15 children
Children with growth hormone deficiency or idiopathic short stature took intranasal GHRP-2 (5 to 15 µg/kg) twice, then three times, a day. Height velocity rose from 3.7 to 6.1 cm a year at six months and 6.0 at 18 to 24 months, with no change in IGF-1 or IGFBP-3; it was well tolerated. There was no control group.
GHRP-2 with a mutated GHRH receptor, 11 patients vs 8 controls
In isolated growth hormone deficiency caused by a homozygous GHRH-receptor mutation, GHRP-2 raised growth hormone 4.5-fold, far less than the 79-fold rise in controls, but clearly. ACTH, cortisol and prolactin were similar in both groups, and TSH did not change. An intact GHRH system is not required for its action.
Pralmorelin: a development profile
A drug profile: developed from Tulane and Polygen work, licensed to Kaken, which kept Japanese rights and sublicensed the US and Canada to Wyeth. It was awaiting approval in Japan as a diagnostic, in phase II in Japan for short stature, and its US phase II development for growth hormone deficiency appeared discontinued. A growth hormone peak cut-off of 15.0 µg/L separated deficiency from health.
KP-102 (GHRP-2) pharmacology in rats and dogs
In conscious rats GHRP-2 released more growth hormone than injected GHRH, and it worked in conscious dogs where GHRH failed, suggesting less sensitivity to somatostatin. It needed the pituitary and, for its full effect, the hypothalamus. It raised ACTH and corticosterone but not prolactin, and three weeks of dosing accelerated growth slightly.
KP-102 (GHRP-2) general safety pharmacology
Across animal models, GHRP-2 at growth hormone-releasing doses had no obvious effect on the central or autonomic nervous system, respiration, circulation, digestion, kidney function or blood, apart from slight ileal contractions at high doses in isolated tissue.
Pralmorelin pharmacokinetics in rats
After a 3 mg/kg intravenous dose in 24 rats, plasma levels fell rapidly in two phases, and biliary excretion was so fast that 80% of the dose was recovered unchanged in bile within an hour. A physiologically based model described its distribution into tissues.
GHRP-2 and GHRP-6 share a receptor (rat pituitary cells)
In primary rat pituitary cells GHRP-2, like GHRP-6, acted synergistically with GHRH. Combining the two peptides at maximal doses added nothing, each desensitised cells to the other but not to GHRH, and a peptide antagonist blocked GHRP-2: the same receptor and mechanism despite different structures.
GHRP-2 releases ACTH from mouse pituitary cells
Mouse anterior pituitary cells express the GHRP receptor, and GHRP-2 directly stimulated ACTH secretion and pro-opiomelanocortin synthesis through cyclic AMP, via both protein kinase A and C pathways, a direct route for the ACTH release seen in people.
Dosing Data
GHRP-2's only approved use is Japan's diagnostic test; its validation study gave 100 µg intravenously, once, after an overnight fast. The other rows are research doses from the studies above, given under supervision.
Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
→ Full GHRP-2 dosage guide — the Japanese diagnostic dose and the research regimens
Side Effects & Contraindications
Reported Side Effects
From the studies above; the Japanese diagnostic has its own label, which we have not read.
Contraindications & Cautions
No US label exists; from the studies above, and a clinician decides.
Legal Status
GHRP-2 is approved only in Japan, as a diagnostic. The sport row below comes from the dataset.
Frequently Asked Questions
?Is GHRP-2 the same as pralmorelin?
Yes. Pralmorelin is the international nonproprietary name for GHRP-2, also coded KP-102 and GPA-748 in development. Under that name it is sold in Japan as GHRP Kaken 100.
?Is GHRP-2 approved anywhere?
Only in Japan, and only as a diagnostic: a single 100 µg intravenous dose to test for growth hormone deficiency. Treatment development for short stature and growth hormone deficiency reached phase II and was not approved.
?Does GHRP-2 raise cortisol or prolactin?
It raises ACTH and cortisol: enough that a cortisol cut-off after the GHRP-2 test identified adrenal insufficiency with about 89% sensitivity and specificity. In rats it raised corticosterone but not prolactin, and in one human study prolactin after GHRP-2 was similar in patients and controls. None of the studies carded here reports a prolactin rise, and this site's earlier claim of one had no source.
?Does GHRP-2 make you hungry?
Yes. Like ghrelin, it increased food intake: seven lean men infused with GHRP-2 ate 35.9% more at a buffet meal than on saline, and every one of them ate more.
?Can GHRP-2 be compounded in the US?
No. FDA's 503A list puts it in Category 3 (nominated without adequate support), which the interim policy does not cover, and it has been in 503B Category 2 (significant safety risks) since September 29, 2023.
?Is GHRP-2 banned in sport?
Yes. WADA's Prohibited List names GHRP-2 (pralmorelin) under S2.2.4, and the Legal table below gives the 2026 and 2027 entries. Doping laboratories detect both the peptide and its metabolite AA-3 in urine.
References
- [other] NIH NCATS Inxight Drugs: pralmorelin (GHRP Kaken 100), marketed by Kaken Pharmaceutical in Japan as a single-dose diagnostic for growth hormone deficiency (read 2026-09-28).
- [fda-pi] US FDA. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A (updated May 14, 2026): GHRP-2 in Category 3, nominated without adequate support.
- [fda-pi] US FDA. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (current as of April 22, 2026): GHRP-2 in 503B Category 2 since September 29, 2023.
- [Human] Bowers CY, et al. "GHRP-2, GHRH and SRIF interrelationships during chronic administration of GHRP-2 to humans." J Pediatr Endocrinol Metab, 1996;9 Suppl 3:261-70. PMID: 8887169.
- [Human] Van den Berghe G, et al. "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." Clin Endocrinol (Oxf), 2002;56(5):655-69. PMID: 12030918.
- [Human] Wideman L, et al. "Synergy of L-arginine and GHRP-2 stimulation of growth hormone in men and women: modulation by exercise." Am J Physiol Regul Integr Comp Physiol, 2000;279(4):R1467-77. PMID: 11004017.
- [Human] Arimura H, et al. "Investigation of the clinical significance of the growth hormone-releasing peptide-2 test for the diagnosis of secondary adrenal failure." Endocr J, 2016;63(6):533-44. PMID: 27020037.
- [Human] Chihara K, et al. "A simple diagnostic test using GH-releasing peptide-2 in adult GH deficiency." Eur J Endocrinol, 2007;157(1):19-27. PMID: 17609397.
- [Human] Veldhuis JD, et al. "Factors other than sex steroids modulate GHRH and GHRP-2 efficacies in men: evaluation using a GnRH agonist/testosterone clamp." J Clin Endocrinol Metab, 2009;94(7):2544-50. PMID: 19351731.
- [Human] Laferrère B, et al. "Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men." J Clin Endocrinol Metab, 2005;90(2):611-4. PMID: 15699539.
- [Human] Okano M, et al. "Determination of growth hormone secretagogue pralmorelin (GHRP-2) and its metabolite in human urine by liquid chromatography/electrospray ionization tandem mass spectrometry." Rapid Commun Mass Spectrom, 2010;24(14):2046-56. PMID: 20552695.
- [Human] Okano M, et al. "Influence of intravenous administration of growth hormone releasing peptide-2 (GHRP-2) on detection of growth hormone doping: growth hormone isoform profiles in Japanese male subjects." Drug Test Anal, 2010;2(11-12):548-56. PMID: 21249726.
- [Human] Kageyama K, et al. "Evaluation of growth hormone-releasing peptide-2 for diagnosis of thyrotropin-producing pituitary adenomas." Endocr J, 2018;65(10):1049-1054. PMID: 29973439.
- [Human] Pihoker C, et al. "Treatment effects of intranasal growth hormone releasing peptide-2 in children with short stature." J Endocrinol, 1997;155(1):79-86. PMID: 9390009.
- [Human] Gondo RG, et al. "Growth hormone-releasing peptide-2 stimulates GH secretion in GH-deficient patients with mutated GH-releasing hormone receptor." J Clin Endocrinol Metab, 2001;86(7):3279-83. PMID: 11443201.
- [Review] "Pralmorelin: GHRP 2, GPA 748, growth hormone-releasing peptide 2, KP-102 D, KP-102 LN, KP-102D, KP-102LN." Drugs R D, 2004;5(4):236-9. PMID: 15230633.
- [Animal] Doi N, et al. "Pharmacological characteristics of KP-102 (GHRP-2), a potent growth hormone-releasing peptide." Arzneimittelforschung, 2004;54(12):857-67. PMID: 15646370.
- [Animal] Furuta S, et al. "General pharmacology of KP-102 (GHRP-2), a potent growth hormone-releasing peptide." Arzneimittelforschung, 2004;54(12):868-80. PMID: 15646371.
- [Animal] Nasu R, et al. "Physiologically based pharmacokinetic model for pralmorelin hydrochloride in rats." Drug Metab Dispos, 2005;33(10):1488-94. PMID: 16033952.
- [In Vitro] Cheng J, et al. "Growth hormone releasing peptides: a comparison of the growth hormone releasing activities of GHRP-2 and GHRP-6 in rat primary pituitary cells." Life Sci, 1997;60(16):1385-92. PMID: 9096259.
- [In Vitro] Kageyama K, et al. "Growth hormone-releasing peptide-2 stimulates secretion and synthesis of adrenocorticotropic hormone in mouse pituitary." Regul Pept, 2009;158(1-3):116-20. PMID: 19682503.
- [Review] Bowers CY. "GH releasing peptides--structure and kinetics." J Pediatr Endocrinol, 1993;6(1):21-31. PMID: 8374685.
- [other] Kaken Pharmaceutical. Injection GHRP Kaken 100 (pralmorelin hydrochloride) package insert, 2nd edition, revised July 2022 (JAPIC; read September 30, 2026): diagnosis of growth hormone deficiency; 100 µg IV in adults, 2 µg/kg up to 100 µg at ages 4 to 17.
Sources & Citations
Every PubMed citation on this page has been checked against its record. The Japanese approval comes from the NIH NCATS record and FDA's categories from its lists, read September 26 to 28, 2026. Grey Peptides sells nothing and links to no vendor.
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