Hexarelin
Hexarelin is a synthetic hexapeptide growth hormone secretagogue studied in the 1990s and 2000s for its ability to release growth hormone and for possible direct cardiovascular effects. Human evidence is limited to small pharmacology and early-phase studies; no regulator has approved it for any indication, and diminishing response with repeated dosing (tachyphylaxis) was noted during its development.
Mechanism
In plain terms, hexarelin tells the pituitary gland to release a pulse of the body's own growth hormone, and in laboratory studies it can also act directly on the heart and blood vessels. Technically, it is a synthetic hexapeptide agonist of the growth hormone secretagogue receptor (GHS-R1a, the ghrelin receptor) on pituitary somatotrophs, triggering pulsatile growth hormone release; it also binds the scavenger receptor CD36 in cardiovascular tissue, which has been proposed to underlie reported cardioprotective effects in animal models. Most mechanistic work is preclinical or from small human studies.
Regulatory Status by Region
- United States (FDA)Not approved for any indication; an unapproved growth hormone secretagogue with no marketed product.
- Australia (TGA)Not on the Australian Register of Therapeutic Goods (ARTG); an unapproved substance with no registered product.
- European Union (EMA)No EMA marketing authorisation; not an approved medicine in the EU.
- WADAProhibited at all times under Section S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics); growth hormone secretagogues and growth hormone-releasing peptides (GHRPs) are explicitly covered.