Overview
Hexarelin (examorelin) is a synthetic hexapeptide and member of the GHRP family, structurally similar to GHRP-6 but with modifications producing greater receptor affinity. It was developed in the late 1980s and has been studied in human clinical trials for GH deficiency, cardiac function, and body composition. Hexarelin is notable for research showing direct cardioprotective effects mediated not through GH but through CD36 receptor binding in cardiac tissue — a mechanism distinct from other GHRPs. This cardiac receptor activity has made it a subject of heart failure and myocardial protection research independent of its GH-releasing properties.
Mechanism
Like other GHRPs, hexarelin activates GHS-R1a to stimulate GH release. Additionally, it has been shown to bind CD36 (fatty acid translocase) receptors on cardiomyocytes and macrophages — a receptor independent of the ghrelin receptor — producing direct cardiac effects including reduced apoptosis after ischemia, modulation of cardiac fibrosis, and improved contractile function in heart failure models. This dual mechanism (GHS-R1a + CD36) distinguishes hexarelin's cardiac research profile from other GHRPs.
Research Areas
Side Effects (Preclinical)
- – Cortisol and prolactin elevation (more pronounced than ipamorelin)
- – Facial flushing
- – Water retention
- – Desensitization with chronic use (more so than other GHRPs)
Cautions
- – For research use only
- – GHS-R1a desensitization with repeated dosing may complicate chronic research protocols
- – Cardiac effects via CD36 are bidirectional depending on context — relevant for cardiac research designs
What the research shows
Hexarelin’s cardiac data represents its most interesting differentiation from other GHRPs. Multiple animal studies have shown reduced infarct size, improved post-ischemic recovery, and reversal of cardiac fibrosis through CD36-mediated mechanisms that operate even in hypophysectomized (GH-removed) animals, confirming the effect is GH-independent.
For GH secretion research, hexarelin is more potent per microgram than GHRP-6 but shows faster tachyphylaxis (receptor desensitization) with chronic use — a consideration in multi-week research protocols.
References
- Hexarelin reverses cardiac fibrosis in rats with chronic heart failure — Xu X et al. (2008)
- Hexarelin, a growth hormone-releasing peptide, reduces cardiac fibrosis in rats — Torsello A et al. (2007)