GHRP-2

What Is GHRP-2?

GHRP-2 (pralmorelin, D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2) is a synthetic growth hormone secretagogue that binds the ghrelin receptor (GHS-R1a) on pituitary somatotrophs and triggers a pulse of growth hormone release. It belongs to the same class as ipamorelin, GHRP-6, and hexarelin: each is a GHS-R1a agonist that activates a calcium and phospholipase-C cascade at the pituitary, producing a GH pulse independent of GHRH tone but additive with it (the Bowers synergy effect).

GHRP-2 differs from ipamorelin in its selectivity profile. On a per-microgram basis it is the second most potent GHRP for GH release, behind hexarelin and ahead of GHRP-6 and ipamorelin, but it also stimulates ACTH and cortisol release and modestly raises prolactin in a dose-dependent fashion. Its orexigenic (appetite) signal sits between ipamorelin, which has almost none, and GHRP-6, which has the strongest. Combined with a GHRH analogue such as CJC-1295 No DAC or tesamorelin, GHRP-2 produces GH responses 3 to 5 times larger than either compound alone in the published human studies.

As pralmorelin, GHRP-2 reached Phase 2 in the US and EU as a treatment for adult and paediatric GH deficiency but was discontinued after underperforming in patients with diseased pituitaries. Kaken Pharmaceutical obtained Japanese approval in 2004 for use as a single-administration diagnostic test of GH deficiency, which remains its only regulatory approval.