Understand the source comparison
Biological Activity and Receptor Binding Comparison
| Peptide Name | Amino Acid Sequence Length | GHRHR Binding Affinity (Ki) | GH Secretion Potency (vs Native GHRH) | Half-Life in Circulation | Clinical/Research Status | Bottom Line ||—|—|—|—|—|—|| GHRH(1-29) / Sermorelin | 29 residues (Tyr¹ to Leu²⁹) | 1.2 nM
No winner is assigned.
This page preserves a source comparison for education. It does not add a rating, recommendation or clinical judgment.
- | Peptide Name | Amino Acid Sequence Length | GHRHR Binding Affinity (Ki) | GH Secretion Potency (vs Native GHRH) | Half-Life in Circulation | Clinical/Research Status | Bottom Line ||—|—|—|—|—|—|| GHRH(1-29) / Sermorelin | 29 residues (Tyr¹ to Leu²⁹) | 1.2 nM | 100% (equipotent to full-length GHRH at GHRHR) | ~10–15 minutes | FDA-approved 1997–2008, now research-only | Identical peptide. Nomenclature difference only. Full biological activity retained. || GHRH(1-44) (native hormone) | 44 residues | ~1.0 nM | 100% (reference standard) | ~7–10 minutes | Endogenous form, rarely synthesized | Longer but no functional advantage. Residues 30–44 are biologically inert at GHRHR. || Modified GH Secretagogues (e.g., CJC-1295) | 29–30 residues + modifications | Variable (0.5–5 nM) | Variable (50–200% depending on analogue) | 6–8 days (with DAC modification) | Research-only, not FDA-approved | Structural analogues designed to extend half-life. Not the same peptide as sermorelin. |
- This table underscores a key point: GHRH(1-29) and sermorelin are functionally interchangeable because they are the same molecule. The 29-amino-acid sequence retains 100% of the biological activity of the full 44-residue native hormone. Receptor binding studies show identical Ki values, and in vitro assays measuring growth hormone release from cultured pituitary cells demonstrate equipotent dose-response curves. The shorter half-life (10–15 minutes) is inherent to the unmodified peptide structure; chemically modified analogues like CJC-1295 extend circulation time through albumin binding but represent distinct molecular entities with different regulatory and research considerations.