GHRP-2

GHRP-2, also known as pralmorelin, is a synthetic hexapeptide growth hormone secretagogue and ghrelin-receptor agonist. It belongs to the growth hormone-releasing peptide family first characterized by Bowers and colleagues, a class of small synthetic secretagogues that release growth hormone through a mechanism distinct from growth hormone-releasing hormone ^[1][3].

Unlike growth hormone itself, GHRP-2 does not replace the hormone but stimulates the pituitary to secrete more of its own, acting through the growth hormone secretagogue receptor GHS-R1a at both pituitary and hypothalamic sites ^[3]. This preservation of the body's natural pulsatile rhythm is a defining feature of the secretagogue approach.

Its research and clinical applications are unusually well developed for a peptide of this kind. GHRP-2 is effective by intravenous, oral, and intranasal routes; an intranasal course in children with short stature was well tolerated and modestly increased growth velocity ^[1]. It has been studied as part of the neuroendocrine regulation of the growth hormone axis, including its interaction with estrogen in postmenopausal women ^[2], and as a probe of growth hormone reserve, where the GHRP-2 stimulation test is used clinically, notably in Japan, to diagnose adult growth hormone deficiency ^[3]. It has also been examined in critical illness, where growth hormone secretagogues can reactivate a suppressed axis ^[5], and it is known to induce adrenocorticotropic hormone alongside growth hormone ^[4].

GHRP-2 is not an approved general medicine in most countries and is used as a research peptide and diagnostic agent; it tends to increase appetite through its ghrelin-mimetic action. It is supplied as a lyophilized peptide for reconstitution and, in some settings, as intranasal or oral preparations.

GHRP-2 is a growth-hormone secretagogue, and boosting GH and IGF-1 can cause fluid retention and edema, joint pain, carpal tunnel symptoms, reduced insulin sensitivity with higher blood glucose, and increased appetite. GHRP-2 in particular can also raise cortisol and prolactin. Long-term human safety data are limited and it is unapproved for these uses, and sustained elevation of GH/IGF-1 carries theoretical risks around tissue overgrowth, so it should be treated as a research peptide.

GHRP-2, also called pralmorelin and KP-102, is a synthetic six-amino-acid growth hormone secretagogue that grew out of the pioneering work of Cyril Y. Bowers, whose laboratory developed the growth hormone-releasing peptide series beginning with studies of enkephalin-derived analogues in the 1970s and 1980s. These peptides were found to release growth hormone through a receptor distinct from that of growth hormone-releasing hormone, a line of research that ultimately led to the discovery of the ghrelin receptor in 1996 and the hormone ghrelin in 1999.

GHRP-2 itself was shown to be a potent secretagogue active by intravenous, oral, and intranasal routes; a 1997 clinical study demonstrated that intranasal GHRP-2 increased growth velocity in children with short stature. Its reliable growth hormone response later formed the basis of the clinical GHRP-2 stimulation test, and it was approved in Japan as a diagnostic agent.

GHRP-2 is respected as a clean and potent way to prompt the body's own pulse of growth hormone, and it is frequently favored for the reliability of that response, so much so that it became the basis of a formal diagnostic test of growth hormone reserve. Users appreciate that because it amplifies natural signaling, the released hormone still follows the body's pulsatile rhythm, and its activity by oral and intranasal routes adds practical flexibility. Its accompanying boost to appetite, stemming from ghrelin-mimetic activity, is seen as useful in research on low intake and wasting. It should be acknowledged that outside its diagnostic use it remains a research peptide rather than an approved therapy, and it can also raise ACTH and cortisol. On the whole it is regarded as one of the more dependable and well-characterized secretagogues.