GHRP-2

GHRP-2 is a member of the growth hormone-releasing peptide family that began with GHRP-6 and also includes hexarelin and ipamorelin. Its generic drug name is pralmorelin. In the 1990s it was developed as a possible treatment for short stature in children, including an oral version tested by Wyeth-Ayerst under the code GPA-748 ^[1].

It found its lasting role in diagnosis instead. Japan’s KEGG drug database lists pralmorelin hydrochloride, brand name GHRP, as a Japanese-approved diagnostic reagent for endocrine function ^[2], and Japanese endocrinologists use the “GHRP-2 test” to check for adult growth hormone deficiency ^[3][4].

GHRP-2 activates the ghrelin receptor (GHS-R1a) on the pituitary and hypothalamus, producing a rapid pulse of GH. In pigs, GHRP-2 was more potent than ipamorelin or GHRP-6 but produced a smaller maximum GH response, and unlike ipamorelin it raised ACTH and cortisol ^[5]. In people, the GHRP-2 test also releases ACTH, and a 2022 study argued that measuring ACTH during the test helps pick up adrenal insufficiency that often accompanies GH deficiency. Of 36 patients with hypothalamic or pituitary disorders in that study, 17 had secondary adrenal insufficiency, and 16 of those 17 also had severe GH deficiency; the ACTH response to GHRP-2 screened for pituitary-related adrenal insufficiency with 83% sensitivity and 88% specificity ^[4].

Like ghrelin, GHRP-2 increases appetite. In a controlled study, seven lean healthy men given a subcutaneous infusion of GHRP-2 ate about 36% more at a buffet meal than on a saline day, and every participant ate more ^[6]. Because it acts on a different receptor from GHRH, GHRP-2 is often paired with GHRH analogues such as CJC-1295; that combination has not been studied in published trials.

The strongest data concern diagnosis. In a Japanese validation study of 77 healthy people and 58 patients with GH deficiency confirmed by insulin tolerance testing, a single 100 µg intravenous dose of GHRP-2 produced a mean peak GH of 84.6 µg/L in healthy subjects and 1.36 µg/L in patients. A cut-off of 15 µg/L corresponded to the standard insulin tolerance test threshold, and repeat tests were reproducible ^[3].

Treatment studies were small. A phase 1 study in ten children with short stature measured the pharmacokinetics of a single 1 µg/kg intravenous dose: GHRP-2 had a half-life of about half an hour and produced a predictable GH rise ^[7]. In ten prepubertal children with GH deficiency (average age about 10, and well below average height) given oral GHRP-2 (900 µg/kg twice daily) for a year, seven reported increased appetite in the first six months, but BMI did not change significantly ^[1].

Animal work has recently extended into tissue healing. In a rat model of rotator cuff tear, GHRP-2 reduced inflammatory (M1) macrophages at the repair site and improved histology, bone density and biomechanical strength of the tendon-bone interface at eight weeks ^[8]. This is a single animal study, and it has not been tested in people.

The Japanese diagnostic test uses a single 100 µg intravenous dose after an overnight fast ^[3]. Other human studies used a single 1 µg/kg intravenous dose in children ^[7], an infusion of 1 µg/kg per hour under the skin for 270 minutes in the appetite study ^[6], and 900 µg/kg by mouth twice daily in the paediatric oral study ^[1]. These are the doses reported in the studies, not recommendations. For laboratory reconstitution arithmetic, see our peptide calculator.

In the published studies the effects are mainly hormonal: GH, ACTH and cortisol rise acutely ^[4][5], and appetite increases ^[1][6]. Its long use as a single-dose diagnostic in Japan does not tell us about repeated or long-term dosing, for which there are no adequate safety data. A 2026 clinical review lists prolactin and cortisol elevations, appetite changes, altered glucose and fluid retention among the adverse effects reported with GH secretagogues as a class ^[9].

Pralmorelin is approved in Japan as a diagnostic agent only ^[2]. We found no approval in the UK, US, Canada, Australia or New Zealand. It is named on the WADA Prohibited List as GHRP-2 (pralmorelin) under section S2 and is banned at all times ^[10]. Anti-doping laboratories have identified glycine-extended GHRP-2 analogues in seized and black-market products ^[11]. For national rules on buying research peptides, see our legal status overview.

Research-grade GHRP-2 is sold as freeze-dried powder. No stability data have been published for these products; see our guides to storing peptides and bacteriostatic water.

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