GHRP-2

pralmorelin, KP-102, GPA-748, GHRP-2, D-Ala-D-βNal-Ala-Trp-D-Phe-Lys-NH₂; brand GHRP Kaken 100 (Japan, diagnostic)

Growth hormone axis

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Note on this profile. Pralmorelin is an approved diagnostic agent in Japan (GHRP Kaken 100) for testing growth hormone deficiency. It is not approved as a treatment anywhere. Its use for body composition, appetite or "anti-ageing" is unapproved, and in the United States the FDA has specifically restricted compounding of it.

Summary

Class: Synthetic hexapeptide (6 amino acids, several non-natural); a growth hormone releasing peptide (GHRP) and ghrelin-receptor (GHS-R1a) agonist developed before ghrelin itself was discovered
Mechanism: Mimics ghrelin at pituitary and hypothalamic receptors to release a large pulse of growth hormone, and also raises cortisol, ACTH and prolactin and stimulates appetite
Routes studied: Intravenous (diagnostic; human pharmacology), subcutaneous (human and animal studies; community), intranasal and oral (human pharmacology studies — low bioavailability)
Dose range reported: Approved diagnostic (Japan): 100 µg IV bolus. Human studies: 1 µg/kg IV; 1–3 µg/kg subcutaneous; oral 300–600 µg/kg in short-stature children. Community: 100–300 µg subcutaneous 1–3 times daily, often with a GHRH analogue. No approved treatment dose
Half-life: Short; plasma half-life on the order of 30–60 minutes after IV, with GH peaking at 15–30 minutes and returning to baseline by 2–3 hours
Storage: Lyophilised: refrigerate. Reconstituted: refrigerate; community practice is use within ~4 weeks
Regulatory status: Approved diagnostic in Japan †; not approved anywhere as a treatment. On FDA's 2023 Category 2 compounding list

Doses are as reported in studies or by the community — never recommendations.

1What it is

GHRP-2 belongs to a family of small synthetic peptides created by Cyril Bowers and colleagues at Tulane from the late 1970s onward by modifying enkephalin (an opioid peptide) until it released growth hormone without any opioid activity. GHRP-6 came first; GHRP-2 was a more potent successor developed in the early 1990s with Kaken Pharmaceutical in Japan. These peptides were the tool that led to the discovery of the ghrelin receptor in 1996 and then of ghrelin itself in 1999 — the body's own "hunger hormone", which turned out to be the natural ligand for the receptor the GHRPs had been hitting all along.

In Japan, pralmorelin was approved as a diagnostic test for GH deficiency. In the rest of the world it never became a medicine. It remains in community use as a strong GH releaser, with the trade-off that it is less selective than ipamorelin: it raises cortisol and prolactin and noticeably stimulates hunger.

2How it's thought to work

Pituitary GH release. binds on somatotrophs, acting through a different second-messenger pathway from GHRH, which is why combining the two is more than additive.

Hypothalamus. stimulates GHRH-releasing neurons and may reduce somatostatin tone, which amplifies the pulse further.

HPA axis. raises ACTH and cortisol acutely, more than ipamorelin, less than GHRP-6 in some comparisons; also raises prolactin.

Appetite. ghrelin-receptor activation in the hypothalamus increases hunger within an hour of dosing.

Other ghrelin-mimetic effects. animal data on gut motility, cardioprotection and anti-inflammatory signalling, as for ghrelin.

Activates the ghrelin receptor: a large pulse of growth hormone, plus smaller rises in ACTH/cortisol (adrenal) and prolactin.Schematic — not to scale

3What the research shows

Diagnostic GH stimulation

In Japanese trials, 100 µg IV pralmorelin produced a robust GH peak in healthy adults and distinguished severe adult GH deficiency with sensitivity and specificity comparable to insulin tolerance testing, with a GH cut-off of 9 ng/ml (Chihara 2007, Eur J Endocrinol). This is the basis of the Japanese approval and the best controlled human evidence. [2]

Graded A/B

GH release and pharmacology

Single IV or doses in healthy adults release more GH than GHRH alone, and the combination of GHRP-2 with GHRH produces a synergistic peak several-fold higher than either (Bowers 1990, J Clin Endocrinol Metab; Arvat 1997). Oral and intranasal GHRP-2 release GH at much higher doses because of poor bioavailability (Pihoker 1997, J Endocrinol — oral in children). [1][3]

Growth in children with short stature

Open-label studies of oral or subcutaneous GHRP-2 in GH-deficient and short children reported increased growth velocity over 6–12 months in some participants (Mericq 1998, J Clin Endocrinol Metab; Pihoker 1997). Small, uncontrolled or partly controlled, and never pursued to approval. [3][4]

Graded A (small)

Appetite and food intake

A placebo-controlled crossover study in healthy men found a subcutaneous GHRP-2 infusion increased food intake by about a third (Laferrère 2005, J Clin Endocrinol Metab). This supports its ghrelin-mimetic identity and is also the main reason some researchers avoid it. [5]

Graded B/—

Body composition, sleep, recovery

A short study of repeated bedtime GHRP-2 in older adults increased GH and IGF-1 and improved some sleep measures; no robust body-composition trial exists. Community reports of muscle gain or fat loss are anecdotal. Related evidence from other ghrelin mimetics (e.g. MK-677) shows modest lean-mass gains alongside raised appetite and glucose.

Cardiac and anti-inflammatory effects

Rodent and ex-vivo data on cardioprotection and reduced inflammatory signalling via and CD36. No human data.

4Reported side effects and interactions

Literature-reported

flushing, warmth and sweating shortly after IV dosing (common), transient drowsiness, hunger, headache; rises in cortisol and prolactin within normal ranges after single doses; a rise in blood glucose after repeated dosing in some studies; injection-site reactions. Children in long-term studies had no serious events, but numbers were small. Anti-GHRP antibodies were not a notable finding.

Community-reported

intense hunger 30–60 minutes after injection (the hallmark), water retention, tingling in hands, flushing and a brief "head rush", lethargy or sleepiness after dosing, increased cortisol-type effects such as feeling wired or anxious at higher doses, vivid dreams, occasional headache and nausea.

Class-level considerations from GH physiology. raised IGF-1 over time; reduced insulin sensitivity and higher fasting glucose with sustained GH elevation; fluid retention; carpal-tunnel symptoms; theoretical concern in active malignancy. Specific to GHRP-2: chronic cortisol and prolactin elevation have not been studied with repeated daily dosing and are the reason ipamorelin is often preferred.

Interactions. synergistic with GHRH analogues (intended); glucose-lowering medicines may need monitoring if GH/IGF-1 rises; glucocorticoids blunt the GH response; dopamine and antagonists may alter the prolactin effect (theoretical).

Markers researchers commonly monitor

Marker	Why it's watched
IGF-1	the main downstream marker of GH-axis effect; the compound's point is to raise it, and values above the age-adjusted range are the usual reason to reduce exposure.
Cortisol (morning serum or salivary)	GHRP-2 raises ACTH/cortisol acutely; the first marker that separates it from ipamorelin.
Prolactin	also raised by GHRP-2; relevant if libido, mood or breast symptoms appear.
Fasting glucose, fasting insulin, HbA1c	sustained GH elevation and ghrelin-mimetic effects both push glucose up.
Body weight and appetite diary	hunger is the dominant practical effect and can undermine fat-loss aims.
IGFBP-3	for interpreting IGF-1.
Blood pressure and fluid retention	practical GH-excess signs.
General baseline CBC, CMP, lipids

Free for everyone. Safety information is never behind a paywall.

5Reconstitution and handling

Commonly supplied in 5 mg and 10 mg vials. with , swirl gently, refrigerate. Often reconstituted together with Mod GRF 1-29 or sermorelin; the calculator supports a two-peptide mix. Doses in human studies were given fasting, because glucose and fatty acids blunt GH release.

Open in calculator, pre-loaded →

6Commonly studied alongside

GHRH analogues — Mod GRF 1-29/CJC-1295, sermorelin, tesamorelin (synergistic GH release; the GHRP + GHRH combination is well documented in acute human studies), GHRP-6 and ipamorelin (as alternatives within the same class), MK-677 (oral ghrelin mimetic; community).

Informational cross-links. Not stack recommendations.

7Regulatory status by region

Region	Status (checked —)
United States	Not FDA-approved. Placed in Category 2 of FDA's bulk drug substances list for compounding (2023), citing safety concerns; compounding pharmacies are restricted from using it
European Union	Not authorised
United Kingdom	Not licensed
Australia	Not approved; prescription-only (Schedule 4) classification for GH secretagogues
South Africa	Not registered
Japan (for reference)	Approved as a diagnostic agent for GH deficiency (GHRP Kaken 100, pralmorelin hydrochloride) †
Sport	Prohibited by WADA (S2 — growth hormone secretagogues; GHRP-2 is named on the list). Several athlete sanctions have involved GHRP-2

8Open questions

Does chronic daily GHRP-2 at community doses change body composition in adults? No controlled trial.
What do repeated daily cortisol and prolactin pulses do over months?
Does the pituitary desensitise with continued GHRP exposure? Acute studies suggest sustained response over days to weeks; long-term data are absent.
Why did pralmorelin never progress beyond a diagnostic in Japan?

9References

1Bowers 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. J Clin Endocrinol Metab. PubMed · DOI
2Chihara K et al. (2007). A simple diagnostic test using GH-releasing peptide-2 in adult GH deficiency. Eur J Endocrinol. PubMed · DOI
3Pihoker C, Badger TM, Reynolds GA, Bowers CY (1997). Treatment effects of intranasal growth hormone releasing peptide-2 in children with short stature. J Endocrinol. PubMed · DOI
4Mericq V et al. (1998). Effects of eight months treatment with graded doses of a growth hormone (GH)-releasing peptide in GH-deficient children. J Clin Endocrinol Metab. PubMed · DOI
5Laferrère B, Abraham C, Russell CD, Bowers CY (2005). Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men. J Clin Endocrinol Metab. PubMed · DOI
6Bowers CY (1998). Growth hormone-releasing peptide (GHRP). Cell Mol Life Sci. PubMed · DOI
7Howard AD et al. (1996). A receptor in pituitary and hypothalamus that functions in growth hormone release. Science. PubMed · DOI
8FDA (2023). Certain bulk drug substances for use in compounding that may present significant safety risks — GHRP-2. PubMed

References are being resolved to PubMed/DOI identifiers; links search PubMed for the citation until then.

† Being confirmed by our reviewers against current sources.

10Community

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11Page history

25 Oct 2026Profile published — awaiting medical review

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