What is GHRP-2?

What sources report

GHRP-2 is a six-amino-acid peptide, H-D-Ala-D-2Nal-Ala-Trp-D-Phe-Lys-NH2, that includes D-2-naphthylalanine, an amino acid the body does not make.³ Its free-peptide formula is C45H55N9O6 (818.0 g/mol), and PubChem lists it as CID 6918245; CID 6852372, which some websites cite, is a different stereoisomer with L-phenylalanine.¹⁴ Unnatural growth hormone-releasing peptides were discovered in 1976, years before ghrelin, the natural hormone they mimic.⁴¹ GHRP-2 came from a series developed by Polygen in Germany and Tulane University in the US, and Kaken Pharmaceutical of Japan developed it as KP-102.⁸³³

It acts at both the hypothalamus and the pituitary, and its growth hormone effect in people depends on the body's own GHRH.³³⁴¹ Given together with GHRH, it released growth hormone synergistically in 12 children.²⁴ It is short-acting: Japan's label gives an elimination half-life of about 0.42 to 0.69 hours after an IV dose, and in 10 children growth hormone peaked about 25 minutes after the dose.⁵²⁵ It is not fully specific: it also raises prolactin, ACTH and cortisol, and a 2026 review describes the cortisol and prolactin rises as transient.²⁹³⁸

Diagnostic use in Japan

• Validation (2007, 135 people): after one 100 µg IV dose, growth hormone peaked within 60 minutes in everyone.⁹ Peaks averaged 84.6 µg/L in 77 healthy volunteers and 1.36 µg/L in 58 adults with severe deficiency, and a 15 µg/L cut-off matched the insulin tolerance test's 3 µg/L.⁹
• Post-marketing survey (503 patients at 19 sites, 2006 to 2012; 502 analyzed): sensitivity 0.853 and specificity 0.885 for severe deficiency, against diagnosis by two or more other tests.⁶
• Pituitary tumors (71 adults aged 18 to 65): against the insulin tolerance test, 81.3% sensitivity and 94.5% specificity.¹⁰
• Children (56 with growth disorders): a weight-based IV dose separated children with and without deficiency, and the test took an hour or less.¹¹
• Adolescents (23, tested 2010 to 2023): two patients passed the GHRP-2 cut-off but failed other tests, so the authors say the adolescent cut-off may need revisiting.⁴⁰
• Beyond the label: in 69 patients assessed for adrenal insufficiency, a cortisol peak below 12 µg/dL during the test was specific to the hypothalamic form among patients whose cortisol response to CRH looked normal.³⁹

A Japanese review calls the GHRP-2 test convenient and safe for adult growth hormone deficiency.³⁶ In the US, the comparable approved test drug is macimorelin (Macrilen), an oral ghrelin-receptor agonist approved in 2017 as a single 0.5 mg/kg dose for diagnosing adult deficiency; Drugs@FDA now lists its marketing status as discontinued.¹⁶⁴⁴

Appetite

GHRP-2 increases eating, as ghrelin does.¹⁹²⁰ A 270-minute infusion under the skin raised buffet intake by 35.9% in 7 lean men, and every subject ate more.¹⁹ In a randomized, double-blind study of 10 lean and 9 obese volunteers, intake rose 10.2% at a low dose and 33.5% at a higher dose, and obesity did not change the effect.²⁰ Seven of 10 children with growth hormone deficiency reported more appetite during the first 6 months of a year of oral dosing, though their BMI did not change in a clinically significant way.²⁸

Growth hormone and IGF-1 over weeks

• Older adults (17 men and women): a 30-day continuous infusion under the skin raised pulsatile growth hormone more than 3-fold on day 1 and more than 1.8-fold on days 14 and 30, and held IGF-1 at a raised plateau.²¹ Safety screening tests stayed normal.²¹
• Children with short stature (15, no control group): intranasal GHRP-2 raised height velocity from 3.7 to 6.1 cm a year at 6 months, without changing IGF-1 or IGFBP-3; 6 children who continued for 18 to 24 months grew 6.0 cm a year.²⁶
• Children with growth hormone deficiency (6, no control group): daily injections under the skin, in rising doses over 6 months and then with GHRH added for 2 months, gave higher growth velocity than before or after treatment without raising IGF-1 or IGFBP-3, and no side effects were seen.²⁷

Critical illness

In 14 patients critically ill for about 40 days, 5 days of GHRP-2 plus TRH raised osteocalcin 19% (placebo, minus 6%) and leptin 32% (placebo, minus 15%) without changing cortisol.²² In 33 men with prolonged critical illness, GHRP-2 alone restored growth hormone secretion and normalized IGF-1, but it did not reduce protein breakdown; that needed added TRH.²³

Animal and lab studies

• In steroid-treated rats, GHRP-2 lowered the muscle-breakdown genes atrogin-1 and MuRF1 without changing IGF-1, acting through the ghrelin receptor in mouse muscle cells.³⁴
• In a rat rotator cuff tear model, it reduced inflammatory M1 macrophages, raised healing scores and bone density at 8 weeks, and improved repair strength at 4 and 8 weeks.³⁵
• In pigs, it was more potent than GHRP-6 and ipamorelin but reached a lower maximum growth hormone level, and it raised ACTH and cortisol, which ipamorelin did not.³⁰
• In the developer's standard animal safety tests, it showed no serious general pharmacological effects at doses that release growth hormone.³³

What has not been shown

A 2026 review places GHRP-2 in its tier B: human data limited to diagnostic use and small studies of growth hormone and appetite, with no controlled efficacy data for performance endpoints such as muscle or fat, and no long-term safety data.³⁸ For laboratory work, GHRP-2 for sale is listed as a 5 mg research vial.

Side effects

Most human safety data describe Japan's diagnostic product, given once by vein.⁵⁶

On Japan's label

• Most common (5% or more): feeling hot (16.0%), abdominal rumbling and a raised white blood cell count.⁵
• Less common (0.1% to under 5%): low blood pressure, nausea, stomach discomfort, bloating, drowsiness, runny nose, sweating, dry mouth, feeling dazed, cold sweat, hunger, tiredness and unsteadiness.⁵
• Frequency unknown: raised ALT (a liver enzyme), abdominal pain, dizziness, shifts in white cell types, bitter taste, back pain, headache and facial flushing.⁵

In trials and surveys

• Before approval, 86 of 227 people (37.9%) in Japan's phase 1 to 3 trials had an adverse reaction, mainly abdominal rumbling, heat sensation, sweating and a raised white cell count.⁶
• A post-marketing survey of 503 patients found no adverse reactions.⁶ During the re-examination period, 2 patients had 5 serious events reported spontaneously (impaired consciousness, facial pallor, abdominal pain, sweating and raised blood pressure); all recovered, and other causes were possible.⁶
• In 6 healthy young adults, it raised prolactin (less than TRH did) and raised ACTH and cortisol about as much as CRH did.²⁹
• In critically ill men, GHRP-2 infused alone raised blood lactate and white cell counts by day 5.²³
• In children, no side effects or toxicities were seen in 6 given daily injections for 8 months, and the intranasal form was well tolerated.²⁷²⁴

Warnings

• FDA cites reports of serious adverse events in people given GHRP-2, including increased insulin needs, deaths of critically ill study subjects, infection and pancreatitis, and notes that causality has not been established.¹⁵
• Immune reactions: FDA says compounded GHRP-2 for injection or nasal use may trigger them, because of potential aggregation and peptide-related impurities.¹⁵
• Blood sugar: a 2018 review of growth hormone secretagogues notes concern about higher blood glucose from lower insulin sensitivity.³⁷
• Pregnancy and young children: Japan's label says not to give it to women who are or may be pregnant, and notes it was not tested in clinical trials in children under 4.⁵
• Pituitary tumors: the label notes reports of pituitary apoplexy, with vision problems, headache and vomiting, when similar drugs were given to people with pituitary adenomas.⁵
• Long-term use: safety is unknown, and the longest published human dosing found was 18 to 24 months of intranasal use in 6 children.³⁸²⁶
• Product quality: research-chemical peptides have uncertain purity, dose consistency and sterility, and an anti-doping lab found about 50 µg of GHRP-2 per tablet in a product sold as a nutritional supplement.³⁸³²
• Athletes: a doping-control urine test detected unchanged GHRP-2 and its metabolite AA-3 in all 10 men given an IV dose.³¹

Dosage information

The only approved dosing on record is Japan's single-dose diagnostic test, which a clinician orders and gives.⁵⁶ No dose is established for any other use, and it has no FDA approval.⁵⁶⁴²

In Japan's test, blood growth hormone is measured before the dose and at 15, 30, 45 and 60 minutes, and a peak of 9 ng/mL or less (recombinant standard) indicates severe deficiency.⁵⁶ Most study doses above were weight-based, and several were continuous infusions. They come from research studies and are not guidance for anyone.

Reconstitution and storage

The only regulator-reviewed handling instructions cover Japan's diagnostic vial, which holds 100 µg of pralmorelin hydrochloride.⁵

• Mixing: dissolved in 10 mL of physiological saline immediately before use and used as soon as possible; stability after dissolving was confirmed for up to 24 hours at room temperature.⁵⁶
• Storage: at 10 °C (50 °F) or below, never frozen, protected from light once the outer box is opened, within a 3-year shelf life.⁵
• The substance: the hydrochloride salt (C45H55N9O6 · 2HCl, 890.90) absorbs moisture and breaks down in light.⁵⁷

The 5 mg research vial listed on this site is a different product, and the supplier states neither its salt form nor any stability data. General lab steps are in How to reconstitute a peptide vial and How to store peptides, and the reconstitution calculator handles the concentration math.

Regulatory status

• United States: no FDA approval. openFDA's Drugs@FDA data held no application for pralmorelin on October 24, 2026.⁴² Kaken had sublicensed US and Canadian rights to Wyeth, whose US phase 2 program for growth hormone deficiency appeared to have been discontinued by 2004.⁸
• FDA compounding lists: since September 29, 2023, GHRP-2 for injectable and nasal use has been in category 2 for outsourcing facilities (503B), substances that may present significant safety risks.¹⁵ The listing stood on FDA's page current as of April 22, 2026.¹⁵ For pharmacy compounding (503A), FDA's May 14, 2026 list puts it in category 3, substances nominated without adequate support.⁴³
• Japan: approved on October 22, 2004 as GHRP KAKEN 100 for Injection, a prescription diagnostic for growth hormone deficiency, and on sale since February 2005.⁶⁵ The 2014 re-examination rated it Category 1, meaning no grounds to change or withdraw the approval.⁶⁵
• Elsewhere: Japan's regulator reported in 2014 that the product was not approved or sold in any other country, and a 2026 review says broader therapeutic use is not supported by widespread regulatory approval.⁶³⁸
• Sport: WADA names GHRP-2 (pralmorelin) under S2.2.4 and prohibits it at all times on the 2026 List.¹² The 2027 List, published September 21, 2026 and in force from January 1, 2027, keeps it there.¹³¹⁴