Hexarelin monograph

Hexarelin

Overview

Hexarelin is a synthetic growth hormone secretagogue peptide that acts as a ghrelin receptor agonist and produces strong acute GH release in humans and animals. It is not an approved medicine in the U.S. or EU, and its bodybuilding use is investigational and legally risky. Human data support GH pulsatility effects, but practical performance and hypertrophy outcomes are not well established.

Pharmacokinetics & Mechanism

• Class: Synthetic growth hormone secretagogue peptide (GHS)
• Mechanism of action: Hexarelin stimulates growth hormone release primarily by activating the growth hormone secretagogue receptor 1a (GHS-R1a), also called the ghrelin receptor, in the hypothalamus and pituitary. It increases pituitary GH secretion and can also influence prolactin and cortisol responses in a dose-dependent fashion. Preclinical literature also describes cardioprotective and metabolic signaling effects, but those are not established as clinical performance benefits in healthy humans.
• Target(s): Primary target: GHS-R1a (ghrelin receptor) on hypothalamic and pituitary pathways. Downstream: growth hormone axis with secondary IGF-1 effects; reported endocrine cross-talk with prolactin and cortisol; somatostatin can blunt GH release. Hexarelin is also discussed in preclinical literature for cardiac and inflammatory signaling, but those are not validated coaching targets.
• Route(s) of administration: Subcutaneous injection is the relevant route in research and community use. Intravenous administration has been used in some human endocrine studies, but this is not a practical coaching protocol. Oral bioavailability is not established and is not a meaningful route for standard use.
• Onset: Rapid endocrine onset after injection; GH rises are typically seen within minutes and are sampled over the first 60-120 minutes in human studies. Exact onset depends on dose and study design. Practical performance onset is not well established.
• Half-life: Short plasma half-life. Published human and review-level sources generally describe hexarelin as a short-acting GHS with an elimination half-life on the order of minutes to tens of minutes, but exact values vary by study and are not consistently reported in accessible abstracts. No validated long-acting or DAC hexarelin product is established in humans; if someone markets an extended variant, that is a separate, non-standard product and should not be assumed equivalent.
• Metabolism / clearance: Clearance is rapid and largely consistent with a short-acting peptide. Specific human metabolic pathways are not well established in the accessible clinical literature; as with most peptides, breakdown by proteolysis and subsequent renal/hepatic handling is expected. Detailed human clearance kinetics are not robustly established.