Ipamorelin vs Sermorelin: GHRP vs GHRH Comparison for GH Secretion | Peptpedia
This comprehensive analysis compares Ipamorelin and Sermorelin based on peer-reviewed clinical research, examining their mechanisms of action, efficacy data, and safety profiles. For complete individual peptide profiles, visit the dedicated research pages linked above.
Ipamorelin and Sermorelin represent two distinct mechanistic approaches to growth hormone stimulation. Ipamorelin is a GHRP (ghrelin receptor agonist) that amplifies GH pulse amplitude; Sermorelin is a GHRH analog that stimulates GH release through the pituitary GHRH receptor. Their mechanisms are complementary, and combination protocols produce supra-additive GH secretion. Ipamorelin is more selective (no cortisol/prolactin release); Sermorelin has prior FDA approval history.
Chemical Identity
Side-by-Side Comparison
| Property | Ipamorelin | Sermorelin |
|---|---|---|
| Drug Class | GHRP (Ghrelin Receptor Agonist) | GHRH Analog (First 29 AA) |
| Receptor Target | GHSR-1a (Ghrelin receptor) | GHRH receptor (pituitary) |
| Half-Life | ~2 hours | ~10-20 minutes |
| Off-target Hormones | None (highly selective) | Minimal (physiological) |
| FDA History | Never approved | Was approved (Geref); withdrawn commercially |
| Mechanism | Amplifies GH pulse amplitude | Stimulates GH pulse frequency |
| Combined Use | Often combined with GHRH analogs | Often combined with GHRPs |
Mechanism Comparison: GHRP vs GHRH
Ipamorelin is a selective GHRP that acts on the GHSR-1a ghrelin receptor on pituitary somatotrophs and hypothalamic neurons. It amplifies GH pulse amplitude and partially suppresses somatostatin (the physiological GH brake). Its selectivity makes it unique among GHRPs: it does not stimulate cortisol, ACTH, or prolactin release at research doses, unlike GHRP-6 and GHRP-2.
Sermorelin is the first 29 amino acids of native GHRH-44, the minimum sequence required for full GHRH receptor activation. It stimulates GH release through the pituitary GHRH receptor, increasing GH pulse frequency through a cAMP-mediated pathway. Because it relies on functional hypothalamic-pituitary axis integrity, Sermorelin's effects are more physiological and subject to the normal somatostatin feedback loop.
Frequently Asked Questions
Research Citations
Sermorelin: a better approach to management of adult-onset growth hormone insufficiency?
Walker RF. (2006). Clinical Interventions in Aging