Hexarelin

Overview

Hexarelin is a synthetic hexapeptide growth hormone secretagogue (GHS) that binds the ghrelin receptor (GHS-R1a). It is one of the most potent peptide-based GH secretagogues, with additional cardioprotective properties studied in preclinical models.

Mechanism of Action

Hexarelin activates GHS-R1a in the anterior pituitary, stimulating pulsatile GH release through a pathway distinct from GHRH. It also suppresses somatostatin release and acts synergistically with endogenous GHRH. Additionally, hexarelin has GHS-R1a-independent cardioprotective effects mediated through CD36 scavenger receptor binding.

Research Summary

Clinical studies demonstrated robust GH release in healthy volunteers with peak GH of 40-80 ng/mL following IV 1-2 mcg/kg (Ghigo et al., JCEM, 1994). Significant tachyphylaxis observed with repeated dosing, ~50% attenuation after 16 weeks (Rahim et al., Clinical Endocrinology, 1998). Preclinical rat ischemia-reperfusion models showed reduced infarct size via CD36 (Bhatt et al., Circulation Research, 2006).

Dosing Information

Reported Side Effects

• Transient flushing and warmth after injection
• Increased cortisol and prolactin levels
• Hunger and increased appetite
• Water retention
• Tingling or numbness at injection site

Research References

• Growth hormone-releasing activity of hexarelin, a new synthetic hexapeptide, after intravenous, subcutaneous, intranasal, and oral administration in man (1994)
• The effect of body composition on hexarelin-induced growth hormone release in normal elderly subjects (1998)