GHRP-2
PeptideMedical evidence is limited to GH stimulation RCTs and a diagnostic approval in Japan [s1, s12], while long-term data for therapeutic endpoints are lacking. The community rates GHRP-2 pragmatically more favorably, as users report subjective effects (muscle gain, recovery) without controlled conditions [c1, c2]. The divergence reflects the typical gap between rigorous clinical evidence and experience-based user perception.
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TL;DR
GHRP-2 is a synthetic hexapeptide that activates GHS-R1a receptors via the Gq/11-PLC-IP3-Ca²⁺ signaling pathway to stimulate growth hormone release. It is approved as a diagnostic agent in Japan but classified as a research chemical in most other countries. Both benefit and risk profiles are moderate (3/5 each), warranting careful consideration. Long-term safety data and robust human clinical evidence remain limited.
Description
Synthetic hexapeptide that stimulates growth hormone release via GHS-R1a receptors; approved in Japan as a diagnostic agent, otherwise a research chemical worldwide [s1, s2].
GHRP-2 (Growth Hormone Releasing Peptide-2), also known by the INN Pralmorelin, is a synthetic hexapeptide (D-Ala-D-β-Nal-Ala-Trp-D-Phe-Lys-NH2) that acts as a potent agonist at the ghrelin receptor (GHS-R1a) [s5, s6]. It belongs to the class of growth hormone secretagogues (GHS) and stimulates the release of growth hormone (GH) from the pituitary gland [s5]. In Japan, Pralmorelin was approved in 2004 by Kaken Pharmaceutical under the trade name "GHRP Kaken 100" as a diagnostic agent for the assessment of growth hormone deficiency (GHD) in adults and children aged 4 years and older [s1, s2]. A Japanese multicenter study examined 126 children across 84 institutions [s1]. Outside Japan, GHRP-2 has been approved neither by the FDA nor the EMA for therapeutic or diagnostic purposes [s2, s3]. In addition to GH stimulation, GHRP-2 demonstrates significant appetite stimulation via the same ghrelin receptor in clinical human studies [s7]. Compared to other GHRPs (e.g., GHRP-6, Ipamorelin, Hexarelin), GHRP-2 is considered the second most potent GH stimulator after Hexarelin, but exerts a greater influence on cortisol and prolactin than Ipamorelin [s8, s9]. GHRP-2 is frequently used in the biohacking and bodybuilding community in combination with GHRH analogues (e.g., CJC-1295/MOD-GRF 1-29) to generate synergistic GH pulses. However, this application occurs entirely outside any approved framework and is associated with considerable legal and health risks [s3, s4, c1, c2]. GHRP-2 is listed on the WADA Prohibited List (Class S2) and included in the German Anti-Doping Act (AntiDopG), strictly prohibiting its use in sport [s4].
Legal Status (DE)
In Germany, GHRP-2 is not approved as a medicinal product. It is classified as a research chemical and may not be marketed or sold for human use. Under § 6a AMG, possession for doping purposes is prohibited. GHRP-2 is listed on the WADA Prohibited List (S2: Peptide Hormones and Growth Factors) and is covered by the German Anti-Doping Act (AntiDopG). In Japan, Pralmorelin is approved as a diagnostic agent for growth hormone deficiency (Kaken Pharmaceutical, since 2004). No therapeutic approval exists in the EU or the USA [s1, s2, s3, s4].
Mechanism of Action
{'ghs_r1a_pathway_source_ids': ['s23', 's24'], 'note': 'Commercial sources s5/s6 should be replaced by s23 and s24 for the description of the Gq/11-PLC-IP3-Ca²⁺ signaling pathway. '}
Dosing
GH-Diagnostik (Wachstumshormonmangel)
- Dose
- 1 mcg/kg body weight i.v. as single dose
- Frequency
- einmalig (Stimulationstest)
- Route
- oral
- Duration
- Einmaldosis
- Timing
- Fasted, in the morning
- With food
- vermeiden
GH-Stimulation (Forschungsprotokoll, subkutan)
- Dose
- 100–300 mcg per injection; saturation dose approx. 200–300 mcg (~2–3 mcg/kg)
- Frequency
- 2–3× täglich
- Route
- injektion-subkutan
- Duration
- 8–16 Wochen (Forschungsprotokoll)
- Timing
- Morning fasted, post-training, before sleep; at least 2h interval from meals
- With food
- vermeiden
Appetitstimulation (experimentell)
- Dose
- 1 mcg/kg/h subcutaneous infusion
- Frequency
- Einmalig (270 Minuten)
- Route
- injektion-subkutan
- Duration
- Einmaldosis
- Timing
- Fasted state
- With food
- vermeiden
No officially established safe upper limit for therapeutic use outside Japan. In research protocols, the saturation dose of ~300 mcg per injection is considered a plateau; higher doses do not further increase the GH response but do increase the risk of adverse effects [s10, s11]. Long-term high-dose use has not been evaluated.
GHRP-2 is not approved for human use in Germany. All dosing information is derived from research studies or off-label sources and does not constitute a therapeutic recommendation. Meals (particularly high in carbohydrates or fat) significantly reduce the GH response [s10]. Combination with GHRH analogues (CJC-1295) synergistically amplifies the GH pulse [s9].
Calculate reconstitution, plan dosing, look up injection technique
Side Effects
| Side Effect | Frequency | Severity |
|---|---|---|
| Cancer risk | selten | leicht |
Contraindications
Interactions
Synergistic
GHRP-2 and CJC-1295 (No DAC) act together via two complementary mechanisms, producing a GH pulse 3–5 times greater than with either agent alone. CJC-1295 increases the amplitude of baseline GH pulses, while GHRP-2 increases pulse frequency. This combination is considered one of the most effective for optimizing growth hormone release.
Ipamorelin and GHRP-2 share the same receptor (GHS-R1a); concurrent use therefore yields diminishing additional benefit with increased side effects. If ipamorelin is preferred, it can replace GHRP-2 in GHRH combination stacks, offering a more favorable side-effect profile (less cortisol and prolactin elevation).
MK-677 is an orally active GHS-R1a agonist with a mechanism of action similar to GHRP-2. Combination provides sustained (oral) plus pulsatile (subcutaneous) GH stimulation, but increases the risk of water retention, elevated fasting blood glucose, and prolactin elevation.
GHRP-2 and CJC-1295 DAC act synergistically via complementary receptor pathways (GHS-R1a and GHRHR), generating a synergistic GH pulse. CJC-1295 DAC provides sustained GHRH stimulation due to its longer half-life, while GHRP-2 adds acute GH pulses.
Caution
Concurrent use of GHRP-2 and GHRP-6 results in markedly diminishing returns due to receptor overlap. Additionally, adverse effects such as cortisol and prolactin elevation and pronounced appetite stimulation are potentiated.
Hexarelin is the most potent GHRP representative but produces the greatest cortisol and prolactin elevation. Combining it with GHRP-2 adds these side effects and offers no substantial additional GH benefit given the same receptor population.
High insulin levels inhibit GH release via somatostatin, thereby reducing the efficacy of GHRP-2. Administration of GHRP-2 in the postprandial phase or together with insulin substantially attenuates the GH pulse.
Tesamorelin is a GHRH analogue that activates GHRHR similarly to CJC-1295. Combination with GHRP-2 can produce synergistic GH release, but carries the risk of supraphysiological IGF-1 levels and overstimulation of the somatotropic axis with prolonged use.
Sermorelin is a GHRH fragment with a similar mechanism of action to CJC-1295. Combination with GHRP-2 can amplify GH pulses but increases the risk of supraphysiological IGF-1 levels and associated side effects such as insulin resistance and fluid retention.
Studies
Tier A — High Evidence
Outcome: Food intake (kcal) after GHRP-2 vs. placebo
Effect Size: Significantly increased caloric intake after GHRP-2 (AUC GH: 5550 ± 1090 vs. 412 ± 161 mcg/L/240min, p=0.003)
Outcome: GH response to 1 mcg/kg GHRP-2 i.v.; diagnostic cutoff GH >15 mcg/L in healthy subjects vs. <15 mcg/L in GHD
Effect Size: Sensitivity and specificity of the stimulation test for GHD; Japanese approval in 2004 based on this data
Tier B — Moderate Evidence
Outcome: Dose-dependent GH release following subcutaneous GHRP-2 administration (100–300 mcg); saturation dose ~200–300 mcg
Effect Size: Plateau of GH response at approximately 200–300 mcg; no further increase at higher doses
Outcome: Overview of the history, mechanism, and clinical development of GH secretagogues including GHRP-2
Effect Size: Summary of pharmacology, clinical studies, and development history
Tier C — Low Evidence
Outcome: General pharmacological characterization of KP-102 (GHRP-2) in animal models
Effect Size: Establishment of the pharmacological profile as a basis for clinical studies
Community Evidence
Top reported benefits
- Improved post-exercise recovery
- Increase in muscle mass when combined with GHRH analogues
- Marked appetite stimulation (rated positively by users in a caloric deficit)
- Improved sleep (in some users)
- Subjectively perceptible GH pulse effect
Top reported issues
- Uncontrollably intense hunger (undesirable for many users)
- Water retention
- Sleep disturbances with evening administration
- Dizziness / transient blood glucose drop post-injection
- Many users prefer Ipamorelin due to its lower side effect profile
Isolated severe reactions (hypertension, dyspnea) have been reported in German forums following injection, possibly attributable to contaminated research chemicals [c2]. Quality control for non-approved research chemicals is not guaranteed. Users report considerable quality variability between different suppliers. The total number of analyzed posts is below the target minimum threshold of 30; actual data basis: approximately 23 identifiable reports.
Scientific Sources
- Pralmorelin: GHRP 2, GPA 748, growth hormone-releasing peptide 2, KP-102 D, KP-102 LN, KP-102D, KP-102LN
Adis International Ltd (2004). Drugs in R&DBPMID:15230633 - GHRP-2 Dosage, Half-Life & Protocol Guide
Milligram Editorial Team (2024). MilligramappCLink - GHRP-2 Dosage Guide: Cycles, Half-Life, Side Effects & CJC-1295 Stack
Peptide Reference Editorial Team (2024). Peptide ReferenceCLink - Pralmorelin (GHRP-2): Multicenter diagnostic trial for GH deficiency
Kaken Pharmaceutical Clinical Study Group (2004). Japanese Regulatory Submission / Drugs in R&DAPMID:15230633 - GHRP-2 Dosage Guide: Growth Hormone Releasing Peptide-2 Protocols & What the Research Shows
PeptideWiki Editorial Team (2024). PeptideWikiCLink - Systematic review: the safety and efficacy of growth hormone in the healthy elderly
Liu H, Bravata DM, Olkin I, et al. (2007). Annals of Internal Medicine / DARE NCBI BookshelfALink - Growth hormone secretagogues: history, mechanism of action, and clinical development
Ishida J, Saitoh M, Doehner W, et al. (2020). JCSM Rapid CommunicationsBDOI - General Pharmacology of KP-102 (GHRP-2), a Potent Growth Hormone-Releasing Peptide
Furuta S, Shimada O, Doi N, et al. (2004). Arzneimittelforschung / Drug ResearchCDOI - Determination of growth hormone secretagogue pralmorelin (GHRP-2) and its metabolite in human urine by liquid chromatography/electrospray ionization tandem mass spectrometry
Thevis M, Geyer H, Mareck U, et al. (2010). PubMedBPMID:20552695 - The Safety and Efficacy of Growth Hormone Secretagogues
Nass R, Johannsson G, Christiansen JS, et al. (2008). Growth Hormone & IGF Research / Europe PMCBLink - Growth Hormone and Aging
Veldhuis JD, Bowers CY (2010). Endotext / NCBI BookshelfBLink - GHRP-2 (Growth Hormone Releasing Peptide-2, Pralmorelin): Research Evidence & Safety Profile
PeptideInsight Editorial Team (2024). PeptideInsightCLink - Peptide legal in Deutschland? Rechtslage 2026
Peptide Culture Redaktion (2026). Peptide Culture BlogCLink - Pralmorelin — Wikipedia
Wikipedia Contributors (2024). WikipediaCLink - A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of Ashwagandha root in reducing stress and anxiety in adults
Chandrasekhar K, Kapoor J, Anishetty S (2012). Indian Journal of Psychological MedicineCPMID:23439798DOI - A receptor in pituitary and hypothalamus that functions in growth hormone release
Howard AD, Feighner SD, Cully DF, et al. (1996). ScienceCPMID:8875327DOI - Ghrelin is a growth-hormone-releasing acylated peptide from stomach
Kojima M, Hosoda H, Date Y, Nakazato M, Matsuo H, Kangawa K (1999). NatureCPMID:10604470DOI - Insulin-like growth factor (IGF)-I, IGF binding protein-3, and cancer risk: systematic review and meta-regression analysis
Renehan AG, Zwahlen M, Minder C, O'Dwyer ST, Shalet SM, Egger M (2004). LancetCPMID:15094271DOI - GHRP-2 (Pralmorelin): What the Research Actually Shows
Peptidings Editorial Team (2024). PeptidingsCLink - The Prohibited List 2026 — World Anti-Doping Agency
World Anti-Doping Agency (2026). WADAALink - GHRP-2: Potent Growth Hormone Releasing Peptide Guide
Peptidepedia Editorial Team (2024). PeptidepediaCLink - GHRP-2 – Wachstumshormon-Peptid erklärt
Artgerecht Redaktion (2024). Artgerecht LexikonCLink - Growth Hormone Releasing Peptide-2 (GHRP-2), Like Ghrelin, Increases Food Intake in Healthy Men
Laferrère B, Abraham C, Russell CD, et al. (2005). The Journal of Clinical Endocrinology & MetabolismAPMID:15699539DOI - Ipamorelin vs GHRP-2 vs GHRP-6: Selective vs Potent — Which GHRP Is Right for You?
Formblends Editorial Team (2024). FormblendsCLink - GHRP-2: Mechanism, Benefits, Evidence & Safety
Peptide Treatments Editorial Team (2024). Peptide TreatmentsCLink
Community Sources
Storage
Unopened
Lyophilized powder: stored at -20°C, shelf life up to 24 months.
Opened
After reconstitution with bacteriostatic water, store at 2–8°C; use within 30 days. Protect from light.
Notes
Do not freeze reconstituted solution. Avoid repeated freeze-thaw cycles. As GHRP-2 is not approved as a medicinal product outside Japan, no official manufacturer stability data are available for research chemicals.