Hexarelin
Hexarelin (growth hormone secretagogue)
A potent synthetic GH-releasing hexapeptide studied for growth hormone release and direct cardioprotective effects.
Overview
Hexarelin is a synthetic hexapeptide growth hormone secretagogue related to the GHRP family. It strongly stimulates GH release and has also shown direct cardiac effects in research, acting on receptors in heart tissue. Repeated dosing can desensitize the GH response. It is not an approved drug.
Mechanism of action
Agonizes the ghrelin/GH secretagogue receptor to release growth hormone, and binds cardiac CD36 receptors implicated in its cardioprotective effects.
Key studies & citations
- Human1994
Growth hormone-releasing activity of hexarelin, a new synthetic hexapeptide, after intravenous, subcutaneous, intranasal, and oral administration in man
In 12 healthy volunteers, IV hexarelin released about twice as much GH as GHRH; response was dose-dependent and reproducible across routes.
Journal of Clinical Endocrinology and Metabolism - Human1998
Does desensitization to hexarelin occur?
Twice-daily hexarelin for 16 weeks in 12 healthy elderly people cut the GH response by roughly half; attenuation was partial and reversed 4 weeks after stopping.
Growth Hormone and IGF Research - Animal2002
CD36 mediates the cardiovascular action of growth hormone-releasing peptides in the heart
Identified CD36 as the cardiac binding protein for hexarelin; its coronary effects were absent in CD36-null hearts.
Circulation Research - Animal1999
Growth hormone-independent cardioprotective effects of hexarelin in the rat
Seven days of hexarelin prevented ischemia-reperfusion damage in hypophysectomized rats, showing a cardioprotective action not mediated by GH.
Endocrinology - Human2002
GH-independent cardiotropic activities of hexarelin in patients with severe left ventricular dysfunction due to dilated and ischemic cardiomyopathy
Acute IV hexarelin raised ejection fraction in ischemic cardiomyopathy patients but not in dilated cardiomyopathy, despite similar GH release; small study.
European Journal of Heart Failure
Frequently asked questions
How is hexarelin different from ipamorelin?
Hexarelin is more potent at releasing GH but less selective, and it can raise cortisol and prolactin and desensitize with repeated use, unlike the more selective ipamorelin.