Hexarelin

Research-Grade

Hexarelin is a synthetic hexapeptide (His-D-2-methylTrp-Ala-Trp-DPhe-Lys-NH2) in the growth-hormone-releasing peptide (GHRP) family, a super-analog of GHRP-6. In 12 healthy young volunteers, 1 mcg/kg intravenous hexarelin produced about twice the GH release of the same dose of GHRH, with a dose-dependent and reproducible response; subcutaneous bioavailability (by GH response) was about 77%, versus about 5% intranasally and 0.3% orally. In a small comparison study, hexarelin and GHRP-2 produced similar GH responses, and both also raised prolactin, ACTH and cortisol. Hexarelin's distinguishing feature is cardiac activity that appears separate from GH. In hypophysectomized rats (which cannot release GH), seven days of hexarelin protected isolated hearts from ischemia-reperfusion damage, whereas another GH-releasing peptide that does not bind the heart had no effect. Its cardiac binding site was later identified as the scavenger receptor CD36, which mediated a hexarelin-induced rise in coronary perfusion pressure in perfused hearts. In small acute human studies, intravenous hexarelin increased left ventricular ejection fraction in patients with ischemic cardiomyopathy but not in dilated cardiomyopathy. These cardiac findings are preliminary. With repeated use, the GH response attenuates: in 12 healthy elderly people given twice-daily subcutaneous hexarelin for 16 weeks, GH release fell significantly by weeks 4 and 16, but recovered to baseline after a four-week break. Hexarelin is not an approved medicine in the US and has no validated therapeutic dosing regimen.