GHRP-2: Scientific Profile

Publicado el 12 de julio de 2026 · Actualizado el 17 de julio de 2026

GHRP-2 (Pralmorelin; KP-102; CAS 158861-67-7) is a synthetic hexapeptide growth hormone (GH) secretagogue. It acts as an agonist of the GH secretagogue receptor (GHS-R1a, the ghrelin receptor), stimulating pulsatile GH release from the pituitary. Material intended exclusively for research.

GHRP-2, also known by its pharmacological name pralmorelin and by the development code KP-102, is a synthetic hexapeptide belonging to the family of growth hormone-releasing peptides (GHRP). With CAS number 158861-67-7, molecular formula C45H55N9O6 and an approximate molecular weight of 818 g/mol, it is usually sold in its acetate form as a lyophilized powder for research use. It belongs to the class of growth hormone secretagogues (GH secretagogues) and constitutes one of the historical reference compounds for the study of the regulation of the somatotropic axis.

Structurally, GHRP-2 is a hexapeptide that incorporates several non-standard amino acids and D configurations, which confers resistance to proteolytic degradation and greater stability relative to a conventional linear peptide of L-amino acids. Its sequence is described as D-Ala–D-2-Nal–Ala–Trp–D-Phe–Lys with the C-terminus amidated. The presence of bulky aromatic residues, such as D-2-naphthylalanine and D-phenylalanine, is decisive for its affinity for the target receptor. It derives conceptually from the GHRP series of peptides developed from the pioneering work of Cyril Bowers and colleagues on peptide GH secretagogues, a line of research that preceded the discovery of the receptor's endogenous ligand, ghrelin.

The mechanism of action of GHRP-2 centers on its status as an agonist of the growth hormone secretagogue receptor type 1a (GHS-R1a), the same G-protein-coupled receptor that recognizes ghrelin. Activation of GHS-R1a in the anterior pituitary and in the hypothalamus triggers signaling mediated by the phospholipase C pathway, with generation of inositol trisphosphate and mobilization of intracellular calcium, which promotes the release of GH stored in the somatotrope cells. Unlike GH-releasing hormone (GHRH), which acts on a distinct receptor raising cyclic AMP, GHRP-2 operates through a complementary route; therefore, in research models the coadministration of a GHRP with GHRH produces a markedly synergistic GH release, greater than the sum of both stimuli separately. GHRP-2 also attenuates the inhibitory tone of somatostatin and, given its action on the ghrelin receptor, its influence on other regulatory axes has been studied, including a modest stimulation of the secretion of prolactin, ACTH and cortisol, as well as orexigenic effects (appetite stimulation) characteristic of ghrelinergic signaling.

Regarding the documented research applications, GHRP-2 occupies a singular position within this category because, in addition to the extensive body of preclinical work, it has been characterized in clinical studies in humans. Pralmorelin has been used as a test agent to evaluate the secretory reserve of growth hormone, that is, as a diagnostic tool to assess the integrity of the hypothalamic-pituitary axis in contexts of GH deficiency; in Japan its use as a stimulation test came to be formalized. This trajectory provides GHRP-2 with a comparatively robust level of evidence relative to many other peptides of the same family. Research has explored its capacity to induce reproducible and dose-dependent peaks of GH, its rapid kinetics of action, and its relative potency within the GHRP series, placing it among the most potent peptide secretagogues studied. Other lines of preclinical research have examined its role in models of energy metabolism, appetite regulation, and comparative studies of ghrelin receptor signaling.

It is important to frame the level of evidence honestly. Although GHRP-2 has human data in the diagnostic context, its use as an agent to modify body composition, performance, or aging is not supported by broad therapeutic approvals and corresponds to experimental territory. Much of the claims circulating outside the diagnostic sphere come from short-term studies, small series, or preclinical extrapolations. Phenomena such as the concomitant elevation of cortisol and prolactin, the potential desensitization of the receptor with sustained exposure, and inter-individual variability in the GH response are aspects that the literature flags as relevant and that must be taken into account when designing experimental protocols.

In summary, GHRP-2 (pralmorelin, KP-102) is a well-characterized GH secretagogue hexapeptide that acts as an agonist of the ghrelin receptor (GHS-R1a) to stimulate the pulsatile release of growth hormone. Its combination of structural stability, potency, and the existence of clinical data within the diagnostic framework makes it a valuable tool for the investigation of the physiology of the somatotropic axis, ghrelinergic signaling, and models of neuroendocrine regulation.