Overview
Sermorelin and CJC-1295 are both synthetic analogs of endogenous growth hormone-releasing hormone (GHRH), but they represent different generations of peptide engineering with distinct pharmacokinetic profiles. Both bind the pituitary GHRH receptor (GHRHR) to stimulate GH release, but they differ in half-life, receptor binding affinity, and research utility.
Sermorelin: GHRH 1–29
Sermorelin is the acetylated synthetic form of the first 29 amino acids of endogenous GHRH (hGRF 1–29 NH₂), representing the shortest biologically active fragment that retains full GHRHR binding. It carries a C-terminal amide group critical for receptor affinity. Sermorelin has a biological half-life of approximately 10–20 minutes — substantially shorter than CJC-1295 but longer than native GHRH (approximately 7 minutes). It was FDA-approved as Geref (Serono) before market withdrawal in 2008.
CJC-1295: Modified GHRH with Enhanced Stability
CJC-1295 (Mod GRF 1–29 without DAC) incorporates four amino acid substitutions (Ala→Aib at position 2, Gln→Ala at position 8, Ala→Ser at position 15, Leu→Ala at position 27) that prevent cleavage by dipeptidyl peptidase IV (DPP-IV) and other serum proteases. These modifications extend the half-life to 25–30 minutes and increase receptor binding affinity compared to Sermorelin. With the DAC modification, half-life extends to 6–8 days.
Key Differences
| Parameter | Sermorelin | CJC-1295 (No DAC) |
|---|---|---|
| Structure | GHRH 1–29 NH₂ | Modified GHRH 1–29 (4 substitutions) |
| Half-life | ~10–20 min | ~25–30 min |
| DPP-IV resistance | No | Yes |
| Receptor affinity | Moderate | Higher |
| GH pulse | Physiologic amplitude | Higher amplitude |
| Regulatory history | Former FDA approval (Geref) | Research compound only |
Research Applications
Sermorelin is used in research designs requiring a well-characterized GHRH analog with extensive published pharmacological data. Its former FDA approval provides a useful reference standard for study design and historical comparison. CJC-1295 (No DAC) is preferred when stronger or more sustained GH pulse amplitude is required, or when DPP-IV interference needs to be eliminated. CJC-1295 with DAC suits chronic studies where sustained GH-axis stimulation over days per dose is the experimental goal.
Laboratory Considerations
Both peptides are lyophilized and supplied in 2mg vials at Bastion Peptides. Reconstitution with bacteriostatic water at 1–2 mL per vial is standard. Sermorelin and CJC-1295 No DAC reconstituted solutions are stable at 4°C for up to 3 weeks. CJC-1295 with DAC reconstituted solution should be used within 4 weeks and stored at −20°C when not in active use. Gentle swirling only — do not vortex either peptide.
Research Disclaimer: All compounds discussed are intended exclusively for laboratory and research purposes. This content is not medical advice. Bastion Peptides products are not approved for human use, consumption, or therapeutic application.
