Research Only Growth Hormone Axis

Hexarelin

also known as: Examorelin, EP 23905, MF-6003

A high-potency GHRP studied for cardiac protection via a CD36-mediated pathway independent of GH release — but demonstrates clear tachyphylaxis with chronic use.

A methylated analog of GHRP-6 (His-D-Mrp-Ala-Trp-D-Phe-Lys-NH2) with additional affinity for the CD36 scavenger receptor, giving it a dual ghrelin/CD36 pharmacology that has attracted interest in cardiovascular research.

Mechanism of action

Dual agonism at GHS-R1a (ghrelin receptor) and CD36 scavenger receptor. GHS-R1a activation drives GH release. CD36 activation in cardiomyocytes appears to underlie the cardioprotective effects seen in preclinical ischemia-reperfusion models, which persist after GH-axis tachyphylaxis has developed.

Primary uses

Cardiac ischemia-reperfusion research
GH-axis research (limited by tachyphylaxis)

Typical dosing

100–300 mcg 1–2 times daily (short cycles only) (subcutaneous)

Community dosing only. Chronic use produces GH tachyphylaxis; typical protocols cycle 4–6 weeks on / equivalent off.

Regulatory status

Not approved. Advanced through Phase 2 trials in the 1990s but discontinued. Ongoing academic research in cardiac ischemia-reperfusion models through the CD36 pathway.

References

[pubmed] Deghenghi R, et al. "GH-releasing activity of Hexarelin, a new growth hormone releasing peptide, in infant and adult rats." Life Sci, 1994;54:1321-1328.
[pubmed] Bisi G, et al. "Cardiac effects of hexarelin in humans." Eur J Endocrinol, 1999;141:1-4.

Related peptides

GHRP-2

A second-generation GHRP approved as a diagnostic agent in Japan, with more pronounced GH-releasing potency than GHRP-6 but a meaningful prolactin and cortisol rise at higher doses.

GHRP-6

The prototype GHRP — a hexapeptide ghrelin receptor agonist notable for pronounced hunger stimulation and less favorable cortisol/prolactin profile than newer GHRPs.

Ipamorelin

A selective ghrelin receptor agonist that stimulates GH release without the cortisol, prolactin, or ACTH spike seen with older GHRPs like GHRP-6.

Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.