Section 01
What it's used for
Approved Diagnostic Test in Japan
GHRP-2 (pralmorelin) is approved in Japan as a diagnostic test for how much growth hormone the pituitary gland can release. It's considered reliable: a growth-hormone peak below 9-15 ng/mL, depending on protocol, signals deficiency.
▸Clinical wording
GHRP-2 (pralmorelin) is approved in Japan for diagnostic evaluation of pituitary GH secretory reserve. The GHRP-2 stimulation test is considered reliable, with a GH peak cutoff of <9-15 ng/mL indicating GH deficiency, depending on the protocol.
Body Composition Claims Unproven
Claims that GHRP-2 improves body composition in healthy people come only from sellers and online communities — no human study shows lean-mass gain or fat loss. The one animal study found it increased fat mass in mice, opposite of the claim.
▸Clinical wording
Claims that GHRP-2 improves body composition in healthy volunteers appear in vendor and community material, but no published human study was found showing GHRP-2 producing lean-mass gain, nitrogen retention, or visceral-fat reduction. The one relevant animal study identified found that GHRP-2 increased fat mass in mice, the opposite of the claimed effect.
Deep Sleep Research
Researchers observed that taking GHRP-2 before bed significantly increases deep, slow-wave sleep time and boosts growth-hormone pulses during sleep. It is being studied for improving recovery and age-related sleep decline.
▸Clinical wording
GHRP-2 administered before bedtime significantly increases stage 3/4 slow-wave sleep duration and GH pulse amplitude during sleep. This makes it particularly researched for recovery optimization and age-related sleep deterioration.
Heart Protection: Isolated Hearts Only
In isolated rat and rabbit hearts, GHRP-2 protected against blocked-then-restored blood flow injury and improved heart relaxation, without growth hormone. No study found it shrinks heart-attack damage or scarring; evidence is animal-only.
▸Clinical wording
In isolated rat and rabbit heart models, GHRP-2 protected against ischemia-reperfusion injury and myocardial stunning independent of GH release, improving measures of diastolic function such as LVEDP and dP/dt. No publication was found reporting that GHRP-2 reduces infarct size, and no study was found demonstrating anti-fibrotic effects in cardiac tissue; the evidence for this direction is limited to isolated-heart animal models.
Muscle Wasting in Severe Illness
Researchers are studying GHRP-2 in severe tissue-wasting conditions like burns, sepsis, and AIDS-related wasting, where it appears to preserve lean muscle and improve nitrogen balance by boosting growth-hormone-driven protein building.
▸Clinical wording
Research in catabolic states (burns, sepsis, AIDS-related wasting) shows GHRP-2 preserves lean body mass and improves nitrogen balance through GH-mediated protein anabolism.
Bone Healing: Animal Studies Only
In a rat tendon-to-bone healing model, GHRP-2 was linked to better tissue and strength measures, and a separate mouse study found more bone mass, without explaining why. No study shows it boosts bone-building cells; evidence is animal-only.
▸Clinical wording
In a rat rotator-cuff tendon-bone healing model, GHRP-2 was associated with improved histologic and biomechanical bone-healing properties, and a separate mouse study found increased bone mass with GHRP-2, though it did not report an osteoblast-activity mechanism. No publication was found demonstrating that GHRP-2 enhances osteoblast activity or fracture healing specifically; the evidence is limited to these animal models.
Section 02
Mechanism of Action
Triggering release of stored hormone
- It docks onto the hunger-hormone receptor on hormone-making cells of the pituitary gland.
- That docking sets off an internal chain that frees calcium stored inside the cell.
- The calcium surge pushes packets of ready-made growth hormone out of the cell.
▸Clinical wording
GHS-R1a Receptor Agonism
GHRP-2 binds to the growth hormone secretagogue receptor 1a (GHS-R1a) on anterior pituitary somatotrophs, activating Gq/11-mediated phospholipase C signaling. This generates IP3 and DAG, triggering calcium release from intracellular stores and activating PKC. The calcium surge drives exocytosis of stored GH granules.
Pressing the accelerator and releasing the brake
- Beyond the pituitary, it stimulates brain neurons that make the natural growth hormone trigger.
- It also lowers somatostatin, the brain signal that normally brakes growth hormone release.
- Hitting the gland and the brain together produces the strong hormone response.
▸Clinical wording
Hypothalamic GHRH Potentiation
Beyond direct pituitary action, GHRP-2 stimulates hypothalamic GHRH neurons, increasing endogenous GHRH secretion. This dual mechanism — direct pituitary stimulation plus enhanced GHRH release — contributes to the robust GH response. GHRP-2 also suppresses hypothalamic somatostatin tone, removing the primary brake on GH secretion.
Also nudging stress and milk hormones
- Unlike more selective compounds, it prompts the pituitary to release the stress-hormone trigger.
- Cortisol then rises briefly, typically by 15 to 30 percent.
- It also releases prolactin, the milk hormone, from another pituitary cell type.
- These effects grow with dose and are stronger than with ipamorelin.
▸Clinical wording
Cortisol and Prolactin Stimulation
Unlike more selective agents, GHRP-2 activates ACTH secretion at the pituitary level, leading to transient cortisol elevations (typically 15-30% increase). It also stimulates prolactin release through pituitary lactotroph GHS-R1a activation. These effects are dose-dependent and more pronounced than with ipamorelin.
Making the brain feel hungrier
- Acting on hunger-hormone receptors in the brain, it copies ghrelin's appetite-raising effect.
- It switches on hunger-driving neurons in the arcuate nucleus and quietens the fullness signal.
- The appetite effect is moderate: weaker than GHRP-6, stronger than ipamorelin.
▸Clinical wording
Appetite Stimulation
Through hypothalamic GHS-R1a activation, GHRP-2 stimulates appetite — mimicking endogenous ghrelin's orexigenic effects. This involves activation of NPY/AgRP neurons in the arcuate nucleus and suppression of POMC signaling. The appetite stimulation is moderate — less than GHRP-6 but more than ipamorelin.
Protecting heart cells in laboratory work
- It acts on receptors in heart tissue directly, without going through growth hormone.
- In oxygen-starved conditions it reduced heart cell death and improved the muscle's squeeze.
- It also widens coronary vessels through nitric oxide, a natural vessel-relaxing gas.
▸Clinical wording
Cardioprotective Effects
GHRP-2 has demonstrated direct cardioprotective activity independent of GH release, acting on cardiac GHS-R1a receptors to reduce apoptosis and improve contractile function in ischemic conditions. It also promotes coronary vasodilation through nitric oxide-dependent mechanisms.
Section 03
Biological Pathways
- PLC/IP3/DAG/Calcium PathwayGHS-R1a activation engages Gq/11 to activate phospholipase C; IP3 releases ER calcium and DAG activates PKC, triggering GH granule fusion and exocytosis.
- cAMP Cross-TalkAlso induces modest cAMP generation via Gαs coupling and PKC-mediated adenylyl cyclase activation, contributing to synergy with GHRH analogs.
- AMPK/Hypothalamic Energy SensingIn hypothalamic neurons, stimulates AMPK, a master energy sensor, increasing food intake and modulating peripheral energy metabolism.
- GH/IGF-1/MAPK Growth PathwayReleased GH activates ERK1/2 MAPK signaling via JAK2-SHC-Ras, driving cell proliferation, differentiation, and tissue repair alongside IGF-1/PI3K/Akt.
Section 04
Dosage Information
D-Ala-D-βNal-Ala-Trp-D-Phe-Lys-NH2| Route / system | Context | Range studied | Limitation |
|---|---|---|---|
| Intravenous — diagnostic test | Approved in Japan: test for growth hormone deficiency | 100 µg in one injection, whatever the body weight — about 1.1–1.4 µg/kg at 70–90 kg; growth hormone is then measured for two hours | The only approved use of this molecule anywhere: one injection to measure the pituitary, not to treat. One test dose says nothing about repeating it. |
| Subcutaneous infusion — 30 days | Older men and women with low growth hormone output | 1 µg/kg per hour non-stop for 30 days — about 1.7–2.2 mg a day at 70–90 kg; at day 30 growth hormone was still 1.8 times baseline | A pump round the clock, not injections: the steady supply held IGF-1 up. Seventeen people, thirty days, no strength, body-composition or clinical result. |
| Subcutaneous infusion — appetite | Seven lean healthy men, one 270-minute infusion | 1 µg/kg per hour for 270 minutes before a buffet meal; food intake rose about 36% against saline, and every man ate more | The rate used to raise growth hormone also drives eating. One meal in seven men measures appetite, not body weight, and not what weeks of it would do. |
| Intranasal — children's trial | Fifteen children of short stature, 6 to 24 months | 5–15 µg/kg two to three times a day; growth speed rose from 3.7 to 6.1 cm a year by six months, while IGF-1 and IGFBP-3 did not move | Growing children with open growth plates — an endpoint adults do not have. Even here IGF-1 stayed flat: the pulses never reached the marker adults chase. |
| Subcutaneous — self-administration | Circulating practice, outside any trial | 100–300 µg per injection, one to three times a day — roughly 1.1–4.3 µg/kg at 70–90 kg; the flat 100 µg is used at any body weight | Circulating practice, not a finding. The human work dosed per kilogram, by one injection or by pump; repeated flat injections were never tested at all. |
Results
Syringe Fill Level (100u syringe)
Set positive values for: Recommended dose per kg.
Research Use Only. This information is for educational and research purposes only. Not intended for medical advice or self-medication.
Section 05
Protocols
No protocols featuring this peptide yet. Browse All Protocols
Section 06
Stability & Storage
Lyophilised powder
Supplied as a lyophilised white powder; kept at -20 °C for long-term storage (18-24 months) or at 2-8 °C for up to 6 months. It is protected from light and moisture, and reconstituted with bacteriostatic water into a solution that should be clear and colourless.
After reconstitution
The reconstituted solution is kept at 2-8 °C and used within 21-28 days; it is not refrozen once mixed. Its D-amino acid substitutions give it more resistance to protease breakdown than native peptides, though it still has only moderate stability in solution at room temperature.
Section 07
Side Effects & Precautions
GHRP-2's reported effects include appetite stimulation, fluid retention, and transient cortisol and prolactin rises, plus nerve-compression symptoms and minor, self-limiting local and transient reactions.
Increased appetite
GHRP-2 significantly stimulates appetite by activating ghrelin receptors in the hypothalamus. This effect peaks 20-30 minutes after injection and can last 1-2 hours; it is less pronounced than with GHRP-6 but more noticeable than with ipamorelin.
Water retention
Mild fluid retention, particularly in the arms, legs, and face, is common in the first weeks of use. This is a class effect of GH stimulation that typically lessens over 2-4 weeks.
Cortisol and prolactin elevation
- Cortisol rises transiently by 15-30%, at higher doses; not clinically significant in healthy people, but distinguishes GHRP-2 from selective agents like ipamorelin.
- Prolactin also rises moderately, including with chronic use; levels usually stay within the normal range, particularly in people prone to prolactin effects.
Numbness and tingling
Symptoms resembling carpal tunnel syndrome may occur with sustained GH elevation, related to fluid retention affecting areas where nerves are compressed. These symptoms ease with a lower dose.
Injection-site and transient effects
- Mild local pain and redness at injection sites are common and self-limiting.
- Brief dizziness or a head rush after injection is reported by some users and typically resolves within minutes.
Section 08
Regulatory Status
Everywhere else the peptide remains an unapproved research compound, and in competitive sport it is banned outright.
Japan / PMDA
Approved, but only as a diagnostic
Kaken Pharmaceutical markets it as GHRP Kaken 100, a single-dose test for growth hormone deficiency in adults and children over four; it carries no approval as an ongoing treatment.
FDA / EMA
Not approved for any indication
Neither the FDA nor the EMA has cleared GHRP-2 for therapeutic or diagnostic use in the United States or the European Union; it is sold through research-chemical suppliers for laboratory use only.
WADA
Prohibited under category S2
GHRP-2 is a growth hormone releasing peptide under S2 (Peptide Hormones, Growth Factors and Related Substances) of the Prohibited List, banned for all athletes at all times, in and out of competition.
A diagnostic approval in one country does not extend to therapeutic use elsewhere, and it says nothing about products sold outside that approved formulation. Regulatory status differs between jurisdictions and changes over time — check the current rules of your own regulator and sport federation before relying on any of this.
Section 09
Research Studies
- [1]A Receptor in Pituitary and Hypothalamus That Functions in Growth Hormone ReleaseHoward AD, Feighner SD, Cully DF, et al. · Science · 1996
- [2]Ghrelin is a growth-hormone-releasing acylated peptide from stomachKojima M, Hosoda H, Date Y, Nakazato M, Matsuo H, Kangawa K. · Nature · 1999
- [3]Growth hormone-releasing peptide (GHRP)Bowers CY. · Cellular and Molecular Life Sciences · 1998
- [4]Unnatural Growth Hormone-Releasing Peptide Begets Natural GhrelinBowers CY. · Journal of Clinical Endocrinology & Metabolism · 2001
- [5]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 hCRHArvat E, Di Vito L, Maccagno B, et al. · Peptides · 1997
- [6]Concordant and discordant adrenocorticotropin (ACTH) responses induced by growth hormone-releasing peptide-2 (GHRP-2), corticotropin-releasing hormone (CRH) and insulin-induced hypoglycemia in patients with hypothalamopituitary disorders: evidence for direct ACTH releasing activity of GHRP-2Kimura T, Shimatsu A, Arimura H, et al. · Endocrine Journal · 2010
- [7]Growth Hormone Releasing Peptide-2 (GHRP-2), Like Ghrelin, Increases Food Intake in Healthy MenLaferrere B, Abraham C, Russell CD, Bowers CY. · Journal of Clinical Endocrinology & Metabolism · 2005
- [8]A Simple Test for Growth Hormone Deficiency in AdultsMahajan T, Lightman SL. · Journal of Clinical Endocrinology & Metabolism · 2000
- [9]Pretreatment with Growth Hormone-Releasing Peptide-2 Directly Protects against the Diastolic Dysfunction of Myocardial Stunning in an Isolated, Blood-Perfused Rabbit Heart ModelWeekers F, Van Herck E, Isgaard J, Van den Berghe G. · Endocrinology · 2000
- [10]GH-releasing peptides improve cardiac dysfunction and cachexia and suppress stress-related hormones and cardiomyocyte apoptosis in rats with heart failureXu XB, Pang JJ, Cao JM, et al. · American Journal of Physiology-Heart and Circulatory Physiology · 2005
Section 10
Frequently Asked Questions
Yes, at raising growth hormone — this is the best-documented action in the GHRP family. GHRP-2 (pralmorelin) is approved in Japan specifically as a diagnostic test for GH deficiency: a single 100 µg injection reliably provokes a GH peak, measured for two hours, with a cutoff below 9 to 15 ng/mL used to flag deficiency. Beyond that diagnostic use, human evidence for other claimed benefits like improved body composition is much thinner; the one relevant animal study actually found it increased fat mass in mice, the opposite of what is claimed.
Yes — in a controlled study, seven lean healthy men given a 270-minute GHRP-2 infusion before a buffet meal ate about 36% more than on saline, and every participant ate more. This mirrors the appetite-stimulating effect of ghrelin, the natural hormone that activates the same receptor. It is described as moderate compared to other GHRPs — less pronounced than GHRP-6, more than ipamorelin — peaking 20 to 30 minutes after injection and lasting 1 to 2 hours.
The only approved dose is diagnostic: a single 100 µg injection, regardless of body weight, to test pituitary function. Research trials used very different regimens — a continuous pump delivering 1 µg/kg an hour around the clock for 30 days in older adults, or 5 to 15 µg/kg two to three times daily by nasal spray in children with short stature. Self-administration outside any trial circulates at 100 to 300 µg per injection, one to three times a day — a repeated flat-injection pattern that was never actually tested in the published human research.
The most consistent effects are increased appetite, mild water retention that typically eases over 2 to 4 weeks, and transient rises in cortisol (15 to 30%) and prolactin — larger than with more selective agents like ipamorelin. Some people report carpal-tunnel-like tingling or numbness tied to fluid retention, plus mild injection-site reactions and brief dizziness after dosing.
It has one narrow approval: Japan licenses it as a diagnostic agent for growth hormone deficiency testing, marketed as GHRP Kaken 100. The FDA, EMA, and other major regulators have not approved it for any use, so elsewhere it is sold and classified as a research compound. WADA prohibits it under category S2 (peptide hormones and growth factors), banned both in and out of competition.
By weight, GHRP-2 produces the strongest GH release of the original GHRPs, ranked GHRP-2 > GHRP-6 > hexarelin. But GHRP-6 causes stronger appetite stimulation and more pronounced cortisol and prolactin elevation than GHRP-2. So the two are not simply better or worse — GHRP-2 is the more potent GH stimulus per microgram, while GHRP-6 pushes harder on the hunger and hormone-spillover side.
The lyophilised powder keeps 18 to 24 months at -20 °C or up to 6 months at 2-8 °C, protected from light and moisture. Its D-amino acid substitutions make it more resistant to enzymatic breakdown than a natural peptide, though it still has only moderate stability in solution at room temperature. Once reconstituted, keep it at 2-8 °C, use within 21 to 28 days, and do not refreeze it.