GHRP-2

Overview

GHRP-2 (pralmorelin) is a synthetic hexapeptide ghrelin receptor agonist that stimulates pituitary growth hormone release. It is approved in Japan (Kaken Pharmaceutical, 2004) as a single-dose diagnostic agent for GH deficiency, but is NOT FDA-approved in the US and is research-only. Unlike ipamorelin, GHRP-2 is non-selective and modestly raises ACTH, cortisol, and prolactin.

Mechanism of Action

GHRP-2 binds the ghrelin/GHS-R1a receptor on pituitary somatotrophs and in the hypothalamus, triggering Gq-coupled calcium signaling and pulsatile GH release while also suppressing somatostatin tone. At therapeutic and supratherapeutic doses it produces measurable rises in ACTH, cortisol, and prolactin (less than GHRP-6 or hexarelin, but more than ipamorelin) and stimulates appetite through ghrelin-pathway activation.

Research Summary

Pralmorelin is approved in Japan as a diagnostic GH-stimulation test (100 mcg IV; peak GH <15 mcg/L cut-off validated against the insulin tolerance test by Chihara et al., 2007). Arvat et al. (1997) showed GHRP-2 raises GH, prolactin, ACTH, and cortisol in healthy men (comparable to hexarelin). Laferrère et al. (2005) demonstrated GHRP-2 infusion increases food intake in healthy men. There are no FDA-approved indications; anti-aging and performance use is unvalidated grey-market use.

Dosing Information

Reported Side Effects

• Increased appetite (ghrelin effect)
• Water retention
• Facial flushing
• Transient ACTH, cortisol, and prolactin elevation
• Tingling/numbness in extremities
• Injection-site reactions
• Insulin resistance / hyperglycemia risk with sustained GH elevation

Research References

• Pralmorelin: GHRP 2, GPA 748, growth hormone-releasing peptide 2, KP 102 (2004)
• A simple diagnostic test using GH-releasing peptide-2 in adult GH deficiency (Chihara et al.) (2007)
• Effects of GHRP-2 and hexarelin, two synthetic GH-releasing peptides, on GH, prolactin, ACTH and cortisol levels in man (Arvat et al.) (1997)
• Growth Hormone Releasing Peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men (Laferrère et al.) (2005)