Hexarelin: Scientific Profile

Publicado el 12 de julio de 2026 · Actualizado el 28 de agosto de 2026

Hexarelin (Examorelin; development code EP-23905; CAS 140703-51-1) is a synthetic hexapeptide growth hormone secretagogue (GHS) related to the GHRP family. It acts as an agonist of the secretagogue receptor GHS-R1a (the ghrelin receptor) to stimulate the pulsatile release of GH, and it is studied in research for its additional interaction with the CD36 receptor. Material intended exclusively for research use.

Hexarelin, also known as Examorelin and by its development code EP-23905, is a synthetic hexapeptide (molecular formula C47H58N12O6; molecular weight 887.06 g/mol; CAS 140703-51-1) belonging to the class of growth hormone secretagogues (GHS), specifically to the family of growth hormone-releasing peptides (GHRP). Structurally it derives from GHRP-6 and shares the functional motif of this family, incorporating non-natural amino acids (among them a D-2-methyl-tryptophan residue and a D-phenylalanine) and a C-terminal amidation that confer resistance to enzymatic degradation and a relatively high potency within its class. Its sequence, His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2, distinguishes it from other GHRPs by the methylation of the second residue, a feature that has been associated in the preclinical literature with a favorable plasma half-life and bioavailability compared with analogous peptides.

From a mechanistic standpoint, Hexarelin is an agonist of the growth hormone secretagogue receptor subtype 1a (GHS-R1a), the same G protein-coupled receptor on which the endogenous hormone ghrelin acts. Activation of GHS-R1a in the anterior pituitary and in the hypothalamus triggers phospholipase C-dependent signaling pathways, with an increase in inositol trisphosphate and mobilization of intracellular calcium, which promotes the release of growth hormone (GH) from somatotroph cells. Unlike GHRH, which acts on its own receptor, Hexarelin works through a complementary and synergistic pathway; in research models, the co-administration of a GHRP with GHRH produces GH responses greater than those of either one separately. Hexarelin also indirectly modulates somatostatin secretion and stimulates, to varying degrees, the release of prolactin, ACTH, and cortisol, a pituitary-axis profile that has been documented in preclinical studies and in early physiological research in humans.

A feature that has attracted considerable scientific attention is that Hexarelin interacts with the CD36 receptor, a "scavenger" receptor present in cardiovascular tissue and macrophages, in a manner partially independent of GHS-R1a. This interaction has been the starting point of a preclinical line of research on possible cardiac and vascular effects of the peptide—including studies in animal models of ischemia and cardiac remodeling—that are of interest for experimental pharmacology, although they do not constitute an established therapeutic application. The distinction between GHS-R1a-mediated actions (GH secretion) and CD36-mediated actions (direct tissue effects) is a recurring theme in the characterization of this compound.

The documented applications of Hexarelin are concentrated in research on the neuroendocrinology of the somatotropic axis. It has been a classic tool for exploring the physiology of GH secretion, for characterizing the function and regulation of the GHS-R1a receptor, and for studying the feedback mechanisms of the hypothalamic-pituitary axis. In preclinical models it has been used to investigate the dynamics of pulsatile GH release and of the IGF-1 axis, as well as to study desensitization phenomena: sustained exposure to GHS can attenuate the GH response over time, a finding relevant to the design of research protocols. Owing to its affinity for CD36, it is also used as a pharmacological probe in experimental cardiovascular biology studies.

The level of evidence on Hexarelin is intermediate within the universe of research peptides: there is a reasonably broad body of preclinical work and several early physiological studies in humans that document its ability to stimulate GH, given that the molecule was the subject of pharmaceutical development at one time. However, it did not reach approval as a marketed drug, and many of its more specific actions —particularly those linked to CD36 and to cardiovascular effects— come from animal or in vitro models and not from late-phase clinical trials. Therefore, the honest interpretation of the evidence is that Hexarelin is a GH secretagogue well characterized at the basic mechanistic and pharmacological level, but that its applications beyond GH stimulation remain in the realm of experimental research. Any use must be understood in a strictly laboratory and research context, without extrapolation to clinical indications.

In summary, Hexarelin is a GH secretagogue hexapeptide of the GHRP family, an agonist of GHS-R1a and a ligand of CD36, valuable as a research tool for the study of the somatotropic axis, of ghrelin receptor signaling, and of experimental cardiovascular biology. Its combination of potency, structural stability, and dual receptor target explains the continued interest it generates in the preclinical literature.