GHRP-2
Also known as: Pralmorelin · KP-102 · growth hormone releasing peptide 2
The reference growth-hormone-releasing peptide developed as a diagnostic and research tool for GH-axis characterisation, with well-established GH-releasing pharmacology and licensed diagnostic use in some jurisdictions.
GHRP-2 (pralmorelin) is the reference growth-hormone-releasing peptide with licensed diagnostic clinical use in Japan for GH-deficiency testing; intermediate selectivity profile.
Evidence tier: A — ≥1 RCT + meta-analysis or approved clinical use
- Category
- Sleep & Recovery
- Half-life
- Approximately 15-20 minutes plasma
Section 1
Overview
GHRP-2 (pralmorelin) is a synthetic hexapeptide growth-hormone-releasing peptide developed as the reference research and diagnostic tool for GH-axis characterisation. The compound is licensed in Japan (as pralmorelin) for GH-deficiency diagnostic testing, providing a licensed clinical use base that most GHRPs lack. Outside Japan, it functions as a research chemical widely used in GH-axis research applications.
In research-peptide practice, GHRP-2 provides the reference ghrelin-receptor arm signalling for GH-axis research protocols. Its GH-releasing potency is intermediate between the highly-selective Ipamorelin and the most-potent Hexarelin. Off-target effects on cortisol, prolactin, and ACTH release are more pronounced than for Ipamorelin but less than for Hexarelin — the intermediate profile that has motivated its continued use despite the availability of more selective alternatives.
The cognitive-relevance angle is indirect, following the same GH-axis sleep-cognition framework as the other GHRP-family compounds. Direct cognitive-endpoint clinical trials have not been completed, but the mechanism-of-action framework and licensed diagnostic clinical use provide a substantial acute-safety database for research applications.
Section 2
Discovery & History
- Developed as one of the first generation of synthetic ghrelin-receptor agonists for GH-axis research and diagnostic applications.
- Licensed in Japan (as pralmorelin) for GH-deficiency diagnostic testing, providing a licensed clinical use base and substantial acute-safety database from decades of diagnostic clinical use.
- Extensively characterised across the 1990s and 2000s for GH-axis pharmacology, appetite effects, and metabolic effects.
- Widely adopted in research-peptide practice as a reference ghrelin-receptor arm research tool.
- Superseded in some research applications by the more selective Ipamorelin, though GHRP-2 remains the reference GHRP for many research protocols.
Section 3
Mechanism of Action
- 1Ghrelin-receptor (GHSR-1a) agonism on pituitary somatotroph cells, driving GH release from the pituitary — the primary mechanism-of-action.
- 2Moderate off-target effects on cortisol, prolactin, and ACTH release — more pronounced than for Ipamorelin but less than for Hexarelin, providing the intermediate selectivity profile.
- 3Combined pulse-effect with GHRH analogues — GHRP-2 provides the ghrelin-receptor arm signalling that potentiates the GHRH-receptor arm signalling in stack research configurations.
- 4Systemic GH-mediated effects — increased IGF-1 production, downstream metabolic and tissue-repair effects, and CNS-relevant IGF-1 signalling.
- 5Sleep-onset GH pulse augmentation — the indirect cognitive-relevance mechanism via sleep-mediated memory consolidation.
- 6Central ghrelin-receptor effects on appetite regulation via hypothalamic ghrelin-receptor engagement — the appetite-stimulating pharmacology that GHRP-2 shares with the other GHRPs.
- 7Reported effects on body composition (lean mass, adiposity) via the systemic GH mechanism.
Section 4
Researched Benefits
Findings reported in the published preclinical and clinical literature. Effects in research contexts do not constitute claims of therapeutic benefit in humans.
- 1Licensed diagnostic clinical use in Japan providing substantial acute-safety database — an unusual advantage for a GHRP-family compound.
- 2Reference GHRP for GH-axis research protocols with well-characterised pharmacology.
- 3Effective research-tool combination with GHRH analogues for physiological GH-pulse research.
- 4Intermediate selectivity profile between the highly-selective Ipamorelin and the most-potent Hexarelin.
- 5Reported effects on body composition, tissue-repair markers, and metabolic parameters in research applications.
- 6Sleep-onset GH pulse augmentation with indirect cognitive-relevance via sleep-mediated memory consolidation.
- 7Appetite-stimulating effects providing research applications in cachexia and appetite-regulation research contexts.
Section 5
Theoretical Dosing & Protocols
| Route | Dosage | Frequency | Duration | Source |
|---|---|---|---|---|
| Subcutaneous injection (research and licensed diagnostic use) | No sourced dose | Not stated | Not stated | None cited |
Note: No dose figure is shown because none could be confirmed from a cited human trial abstract or a regulatory label.
Section 6
Administration Routes
- Subcutaneous injection — the primary research route.
- Intravenous administration — the licensed diagnostic route.
- Intramuscular administration in some research contexts.
- Oral administration is not viable — the peptide is degraded by gastrointestinal proteases.
Section 7
Safety Profile
Commonly reported
- · Well-tolerated in the licensed diagnostic clinical experience.
- · Injection-site reactions with subcutaneous administration.
- · Occasional headache during initial dosing.
- · Mild transient effects on cortisol and prolactin — the intermediate off-target profile.
- · Appetite stimulation — the expected ghrelin-receptor-mediated effect.
Rare / theoretical
- · Diabetes precipitation or worsening of glycaemic control in susceptible research subjects.
- · GH-mediated effects on cardiac hypertrophy in chronic high-dose research.
- · Theoretical GH-mediated tumour-growth concerns in active malignancy.
- · Rare hypersensitivity reactions.
- · Tolerance development to the GH-releasing effect with chronic use (intermediate between Ipamorelin and Hexarelin).
Contraindications
- · No entry for GHRP-2 was found in the electronic medicines compendium (emc) on 17 October 2026.
- · Active malignancy — theoretical contraindication via the GH-axis mechanism.
- · Pregnancy and lactation.
- · Severe uncontrolled diabetes.
Section 8
UK & EU Regulatory Context
United Kingdom
No entry for GHRP-2 was found in the electronic medicines compendium (emc) on 17 October 2026. The emc is not a complete record of UK authorisations, so check the MHRA Products database.
European Union
Not approved by the EMA. KEGG DRUG (D02040) lists pralmorelin hydrochloride (GHRP) as a Japanese product, a diagnostic reagent for endocrine function.
Section 9
Clinical Studies Summary
GHRP-2 pharmacokinetics and GH-releasing profile
Foundational clinical pharmacology characterisation of GHRP-2's pharmacokinetic profile and GH-releasing effect time-course, establishing the reference pharmacology for the GHRP class and providing the mechanistic framework for the subsequent development of more selective analogues.
GHRP-2 in GH-deficiency diagnostic testing (Japan)
The licensed diagnostic clinical use programme in Japan providing the substantial acute-safety database from decades of clinical use and establishing the reference dose for GH-releasing effect. Pralmorelin remains the licensed diagnostic form in that jurisdiction.
GHRP-2 + GHRH combined GH-release research
Research characterising the combined-arm effect of GHRP-2 plus GHRH analogues on GH pulse magnitude, providing the reference GHRP-arm characterisation for the modern GH-axis stack research practice.
GHRP-2 appetite-stimulating effects and cachexia research
Clinical research applications of GHRP-2 in cachexia and appetite-regulation research contexts, demonstrating the appetite-stimulating effects via the central ghrelin-receptor mechanism. Provides the distinctive research application angle beyond the primary GH-axis research use.
Section 10
Frequently Asked Questions
Section 10a
Practical Research Guidance
Cycle guidance
Reconstitution & storage
UK sourcing notes
Section 11
Sourcing for Laboratory Research
Sourcing GHRP-2 for laboratory research
Researchers in the United Kingdom and elsewhere typically obtain GHRP-2 from specialist research-chemical suppliers. Purity, third-party testing, and supplier transparency are the principal differentiators worth evaluating before placing an order. The two suppliers below are commonly referenced in UK research contexts.
Reminder: this page is educational. Regulation 46(1) of the Human Medicines Regulations 2012 prohibits selling or supplying an unauthorised medicinal product, and some compounds on this site, such as semaglutide, are authorised prescription-only medicines in the UK.