If you’re looking at GHRH analogs for growth hormone research, you’re probably deciding between two peptides: sermorelin and CJC-1295. Both mimic the body’s own growth hormone-releasing hormone. Both stimulate GH release from the pituitary. But they’re not the same compound, and the differences matter for experimental design.
Here’s a clear comparison of what each one does, how they differ, and why researchers choose one over the other (or both).
These compounds are supplied exclusively for in vitro and preclinical research. They are not intended for human consumption, therapeutic application, or diagnostic use.
Sermorelin: The Original GHRH Analog
Sermorelin is a 29-amino-acid peptide consisting of the first 29 residues of the 44-amino-acid native GHRH sequence. That’s not a random truncation — researchers in the 1980s identified that positions 1-29 contain the full biological activity of the native hormone. Positions 30-44 contribute to stability but aren’t required for receptor binding.
The result: sermorelin binds the GHRH receptor (GHRH-R) on pituitary somatotroph cells and triggers the same cAMP/PKA signaling cascade as endogenous GHRH, producing pulsatile GH release. It was one of the first synthetic GHRH analogs developed and has the longest research track record in the class.
Strengths
- Extensive literature: Decades of published research across multiple species and experimental contexts
- Preserves GH pulsatility: Amplifies natural GH pulses rather than creating artificial sustained elevation
- Clean pharmacology: Acts specifically through the GHRH receptor — minimal off-target effects
- Well-characterized safety profile from years of clinical-stage investigation
Limitation
Short half-life. Sermorelin gets chewed up by dipeptidyl peptidase IV (DPP-IV) pretty quickly, which means its biological activity window is relatively brief. For research requiring sustained GHRH-R stimulation, this is a practical constraint.
CJC-1295: Engineering a Longer Half-Life
CJC-1295 was developed specifically to solve sermorelin’s half-life problem. It’s based on the same 1-29 GHRH fragment but with four amino acid substitutions (at positions 2, 8, 15, and 27) chosen to resist DPP-IV degradation. The result: substantially longer biological activity.
CJC-1295 comes in two forms, and the distinction matters:
CJC-1295 with DAC (Drug Affinity Complex)
The DAC version includes a maleimidopropionic acid linker that binds covalently to serum albumin after injection. Since albumin has a ~20-day half-life, this dramatically extends CJC-1295’s residence time in circulation. Published research reports a half-life extension to approximately 6-8 days — orders of magnitude longer than sermorelin’s minutes-to-hours.
The tradeoff: DAC-conjugated CJC-1295 produces sustained, elevated GH levels rather than amplified pulses. This non-pulsatile profile is useful for some research questions but problematic for others, since pulsatile and sustained GH have different biological effects.
CJC-1295 Without DAC (Modified GRF 1-29)
The no-DAC version retains the amino acid substitutions for protease resistance but lacks the albumin-binding complex. It has a longer half-life than sermorelin (~30 minutes vs. minutes) but much shorter than the DAC version. The key advantage: it preserves GH pulsatility — amplifying natural pulses rather than creating sustained elevation.
This version is what’s typically combined with ipamorelin in research protocols.
Head-to-Head: Which One When?
- Research requiring pulsatile GH: Sermorelin or CJC-1295 no DAC
- Research requiring sustained GH elevation: CJC-1295 with DAC
- Shortest duration studies: Sermorelin (fastest onset, fastest clearance)
- Convenience/dosing frequency: CJC-1295 with DAC (less frequent administration)
- Combination with GH secretagogues: CJC-1295 no DAC + ipamorelin (different pathways, synergistic GH response)
The Synergy Angle: GHRH + GHS
GHRH analogs (sermorelin, CJC-1295) and growth hormone secretagogues (ipamorelin, GHRP-6) work through completely different receptor systems — GHRH-R vs. GHS-R1a. They converge on GH release but through independent signaling pathways. Published research shows the combination produces synergistic GH output exceeding what either class achieves alone.
The simplest way to think about it: GHRH analogs increase pulse amplitude (bigger bursts). GH secretagogues increase pulse frequency (more bursts). Together, you get bigger and more frequent GH pulses.
Product Specifications
Sermorelin
- Sequence: hGHRH(1-29)NH₂
- Molecular Weight: 3,357.88 g/mol
- CAS Number: 86168-78-7
- Purity: ≥99% (verified by HPLC)
CJC-1295 (No DAC)
- Sequence: Modified GRF(1-29) with D-Ala², Gln⁸, Ala¹⁵, Leu²⁷ substitutions
- Molecular Weight: 3,367.97 g/mol
- CAS Number: 863288-34-0
- Purity: ≥99% (verified by HPLC)
Key References
- Thorner MO, et al. Acceleration of growth in two children treated with human GH-releasing factor. N Engl J Med. 1985.
- Ionescu M, Bhatt DL, et al. Pharmacokinetic profile of CJC-1295. J Clin Endocrinol Metab. 2006.
- Teichman SL, et al. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I by CJC-1295. J Clin Endocrinol Metab. 2006.
Browse Sermorelin 10mg, CJC-1295 No DAC 5mg, or CJC-1295 with DAC 5mg. All independently tested at Janoshik Analytical. For the popular combination product, see CJC-1295 + Ipamorelin.