Glossary
GHRP
GHRPs are synthetic ghrelin-receptor agonists that trigger pituitary GH release. How GHRP-2, GHRP-6, ipamorelin and hexarelin differ.
GHRPs (growth hormone-releasing peptides) are short synthetic peptides that stimulate pituitary growth hormone release by acting at the ghrelin receptor, GHS-R1a — not at the GHRH receptor. They predate the discovery of ghrelin itself: GHRP-6 was developed from opioid-peptide chemistry in the 1970s and 1980s, and the endogenous ligand for the receptor it hit was not identified until 1999.
How the members differ
Selectivity is the main distinguishing variable. GHRP-6 is a hexapeptide reported to produce marked appetite stimulation through ghrelin-receptor signalling. GHRP-2 is more potent for GH release with less appetite effect but some reported cortisol and prolactin elevation. Ipamorelin is a pentapeptide selected for selectivity, with minimal reported cortisol or prolactin response. Hexarelin is the most potent of the group acutely but shows the fastest receptor desensitisation in published work.
Why it matters
All four are growth hormone secretagogues but they are not interchangeable comparators. Selectivity profile, not raw potency, usually decides which is appropriate for a given research question.
Related terms
GHRH. Browse GHRPs and secretagogues or compare in Ipamorelin vs GHRP-2.