Hexarelin

A synthetic hexapeptide GHRP (Growth Hormone Releasing Peptide) that activates the ghrelin receptor (GHS-R1a) to stimulate GH release from the pituitary — producing the strongest GH pulse of any GHRP-class peptide. Unlike Ipamorelin (which selectively stimulates GH release), Hexarelin also stimulates cortisol and prolactin to a degree, and uniquely activates CD36 receptor-mediated cardioprotective pathways that are independent of its GH-releasing activity. The cardioprotective mechanism has been demonstrated in ischaemia-reperfusion models and is one of the most studied non-GH effects of any peptide in this class.

Among the most studied GHRP-class peptides, with published research spanning GH secretion, body composition, cardiac function, and GH deficiency treatment. Multiple human trials demonstrate robust GH release — significantly greater peak GH than GHRP-2 or GHRP-6. The cardioprotective findings (published in Cardiovascular Research and the American Journal of Physiology) have generated significant interest in heart failure applications. Body composition effects are well-documented: lean mass gain and fat loss consistent with GH elevation. The primary clinical limitation is cortisol co-stimulation, which led to the development of selective GHRPs like Ipamorelin that avoid this effect.

4–8 weeks, then break to prevent desensitisation