What is GHRP-2?
GHRP-2 stands for Growth Hormone-Releasing Peptide 2. Its clinical research name is pralmorelin. It is a small, synthetic peptide — just a short chain of amino acids — created by researchers at Tulane University and Polygen in Germany.[1] Scientists designed it to mimic ghrelin, a natural hormone produced in the gut that tells the brain to release growth hormone (GH) and to feel hungry.[2]
GHRP-2 is a research-use-only compound. It is not an approved drug for general human use in most countries, though it has been studied in clinical trials as a diagnostic tool for growth hormone deficiency.[1] It appears on the World Anti-Doping Agency (WADA) Prohibited List, and sports drug-testing labs have developed urine tests to detect it in athletes.[3]
How GHRP-2 Works
Think of your pituitary gland — a pea-sized gland at the base of your brain — as a factory that makes growth hormone. GHRP-2 is like a doorbell for that factory. When it rings, the factory ramps up production and releases a pulse of GH into the bloodstream.[1]
More specifically, GHRP-2 binds to a receptor called the GH secretagogue receptor (GHS-R) — the same receptor that ghrelin uses.[2] Importantly, research has confirmed that GHRP-2 does not work through the separate growth hormone-releasing factor (GRF) receptor, meaning it has its own distinct signaling pathway.[5] This distinction matters to scientists studying exactly how GH release is controlled.
Beyond the pituitary, GHS-R receptors also exist on muscle cells. Lab studies show that GHRP-2 can act directly on muscle tissue, dialing down the activity of proteins called Atrogin-1 and MuRF1 — molecules that break down muscle fiber during stress or illness.[4] This finding has sparked interest in GHRP-2 as a research tool for understanding muscle wasting.
What the Research Shows
Here is a plain-language summary of key findings from published studies:
- GH release in healthy people: Early research established that GHRP-2 reliably raises GH levels in healthy men and women regardless of age, sex, or body weight. In people with true GH deficiency, the GH response is much blunter — a difference researchers used to set a diagnostic cut-off value.[1]
- Appetite increase in humans: In a controlled human study, seven healthy lean men received a slow subcutaneous infusion of GHRP-2 or a saline placebo, then sat down to a freely available buffet. The men ate about 36% more calories during the GHRP-2 infusion compared to placebo — and every single subject ate more, not just the average.[2] This mirrors what is seen with ghrelin itself, confirming that GHRP-2 activates appetite circuits as well as GH release.[2]
- Muscle protection in the lab: Cell culture and animal studies found that GHRP-2 reduced the expression of muscle-breakdown genes triggered by the stress hormone dexamethasone, and that this protective effect was blocked when researchers used a GHS-R blocker — confirming the receptor pathway is essential.[4]
- Anti-doping detection: Sports testing researchers have shown that GHRP-2 and its breakdown products can be detected in urine for up to roughly 47 hours after nasal administration, making it trackable in doping control.[6] Labs have validated mass spectrometry methods to find GHRP-2 and related peptides in athlete urine samples.[3]
- Diagnostic use: Under the research name KP-102D, pralmorelin was studied in Japan as a diagnostic agent for hypothalamo-pituitary function, with approval applications submitted as of the early 2000s.[1]
What GHRP-2 Is Being Studied For
Researchers have investigated GHRP-2 across several areas:
- Diagnosing GH deficiency — using a single standardized dose to see whether the pituitary responds normally[1]
- Understanding appetite and eating behavior — as a pharmacological tool to probe how ghrelin-like signals influence food intake in humans[2]
- Muscle atrophy and wasting — exploring whether GHS-R activation in muscle cells can slow breakdown processes[4]
- Preclinical growth research — tested in animal models including swine and yaks to study GH release and growth performance
- Anti-doping science — developing detection methods to identify misuse in sport[3][6]
How GHRP-2 Is Dosed in Research
Doses vary widely depending on the research question, the species being studied, and the route of administration. Human studies have used everything from microgram-level injections to milligram-level oral doses in animal models. Rather than restate every number here, please refer to the dosage chart on this page for a full breakdown of protocols from published trials — and use the calculator to work out weight-based amounts for any specific research protocol. All dosing information is provided strictly for reference purposes.
Mixing and Storing GHRP-2
GHRP-2 is typically supplied as a lyophilized powder — a freeze-dried white or off-white solid in a sealed vial. To prepare it for use in research, the powder is reconstituted by slowly adding bacteriostatic water (water with a small amount of benzyl alcohol to prevent bacterial growth) directly to the vial. Aim the liquid at the glass wall, not at the powder directly, and gently swirl — never shake vigorously, as this can break down peptide chains. Once mixed, the solution should be clear and colorless. Store unreconstituted vials in a cool, dry place away from light; many researchers keep them refrigerated at 2–8 °C. After reconstitution, keep the vial refrigerated and use within a few weeks for best stability. Always check your specific supplier's certificate of analysis for purity and recommended handling. These are general research-handling guidelines only and do not constitute medical or pharmaceutical advice.
Sources
- Pralmorelin: GHRP 2, GPA 748, growth hormone-releasing peptide 2, KP-102 D, KP-102 LN, KP-102D, KP-102LN. — Drugs in R&D, 2004. PMID 15230633.
- Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men. — The Journal of clinical endocrinology and metabolism, 2005. PMID 15699539.
- Detection of GHRP-2 and GHRP-6 in urine samples from athletes. — Drug testing and analysis, 2015. PMID 25809000.
- GHRP-2, a GHS-R agonist, directly acts on myocytes to attenuate the dexamethasone-induced expressions of muscle-specific ubiquitin ligases, Atrogin-1 and MuRF1. — Life sciences, 2008. PMID 18191156.
- Growth hormone-releasing peptide-2 (GHRP-2) does not act via the human growth hormone-releasing factor receptor in GC cells. — Endocrine, 1998. PMID 9798733.
- Determination of growth hormone releasing peptides metabolites in human urine after nasal administration of GHRP-1, GHRP-2, GHRP-6, Hexarelin, and Ipamorelin. — Drug testing and analysis, 2015. PMID 25869809.
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