What it is
Hexarelin is a hexapeptide, a chain of six amino acids, in the growth hormone-releasing peptide (GHRP) family. It is a growth hormone secretagogue, meaning it prompts the release of growth hormone (GH). The PeptidesAI encyclopedia describes it as producing a strong GH pulse, and it has also been studied for cardiac effects.
In the encyclopedia it is categorized under growth hormone, alongside other GHRPs such as GHRP-2 and GHRP-6.
How it's thought to work
Hexarelin activates the ghrelin receptor, also called the growth hormone secretagogue (GHS) receptor, to stimulate GH release. It also binds CD36, a cell-surface protein found on heart muscle cells and blood vessel lining cells. In rat hearts, a labeled form of hexarelin bound CD36, and hexarelin raised coronary perfusion pressure in perfused hearts in a way that was absent in hearts from mice lacking CD36. This is the basis for the suggestion that CD36 may underlie hexarelin's reported cardiovascular effects.
What the research says
A review of the growth hormone-releasing peptides describes their GH-releasing activity in humans as marked and dose-related, with partial desensitization on prolonged administration, and notes that prolonged administration of GHRPs increases IGF-1 levels in animals and humans. In a human study in which hexarelin was given by injection for 16 weeks, the GH response to hexarelin was partially and reversibly attenuated, IGF-1 did not change significantly, and the authors concluded that the biological impact of that schedule on the GH-IGF-1 axis seemed minimal.
Hexarelin is not FDA-approved. The cardiac findings referred to here come from animal and laboratory work, not from outcome trials.
Reported side effects
The PeptidesAI encyclopedia lists increased hunger, water retention, tingling, elevated cortisol and prolactin, and potential desensitization over time. Increases in ACTH, cortisol and prolactin have been reported after single injections of GH-releasing peptides, but in the 16-week study above the cortisol response was lower after treatment than before and the prolactin response was unchanged.
Reconstitution
Hexarelin is supplied as a lyophilized (freeze-dried) powder and is typically reconstituted with bacteriostatic (BAC) water before use. It commonly comes in 2 mg and 5 mg vials. The amount of peptide in the vial is fixed; the water added only changes how concentrated the solution is.
Worked example. A 5 mg vial is 5,000 mcg. Reconstituted with 2 mL of BAC water, that works out to 5,000 mcg ÷ 2 mL = 2,500 mcg/mL. On a U-100 insulin syringe, where each unit is 0.01 mL, each unit holds 2,500 × 0.01 = 25 mcg. Use the peptide reconstitution calculator to work out the concentration and units for any vial size and water volume.
Important notes
Hexarelin is not FDA-approved. In the 16-week human study, the authors concluded that the therapeutic potential of chronic hexarelin requires further investigation. Single administrations of GH-releasing peptides can raise cortisol and prolactin.
Sources
- Growth hormone-releasing peptides. Ghigo E et al. Eur J Endocrinol, 1997. Review
- Growth hormone status during long-term hexarelin therapy. Rahim A et al. J Clin Endocrinol Metab, 1998. Human trial
- The effect of chronic hexarelin administration on the pituitary-adrenal axis and prolactin. Rahim A et al. Clin Endocrinol (Oxf), 1999. Human trial
- CD36 mediates the cardiovascular action of growth hormone-releasing peptides in the heart. Bodart V et al. Circ Res, 2002. Preclinical
Frequently asked questions
These questions cover the same ground as the sections above, in a shorter format.
What is hexarelin?
A synthetic hexapeptide growth hormone secretagogue in the GHRP family, studied for GH release and for cardiac effects.
How is hexarelin thought to work?
It activates the ghrelin (GHS) receptor to stimulate GH release, and it also binds CD36, which may underlie reported cardiovascular effects.
What does the research on hexarelin say?
GH release is well documented in human studies, with partial and reversible desensitization over 16 weeks in one study. Cardiac findings come mainly from animal and laboratory work. It is not FDA-approved.
What are the reported side effects of hexarelin?
Increased hunger, water retention, tingling, and cortisol and prolactin increases after single administrations; potential desensitization over time.
How much is one unit from a 5 mg Hexarelin vial?
With 2 mL of BAC water, a 5 mg vial is 2,500 mcg/mL, so one unit on a U-100 syringe (0.01 mL) holds 25 mcg.
The full entry, plus the calculator
The PeptidesAI app has the complete encyclopedia entry for Hexarelin — one of 70 compounds covered — plus the reconstitution calculator, a dose log and reminders. Free to download on iPhone.
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