Same Peptide, Two Radically Different Drugs
CJC-1295 with DAC and CJC-1295 without DAC share a name and the same base peptide. That’s about where the similarity ends. The DAC (Drug Affinity Complex) modification changes the half-life by roughly 100-fold — which completely transforms the pharmacological profile. Choosing the wrong one for your experiment is like choosing between a sprint and a marathon and not realizing they’re different events.
Here’s what the difference actually is, and why it matters for research design.
These compounds are supplied exclusively for in vitro and preclinical research. They are not intended for human consumption, therapeutic application, or diagnostic use.
The Base Peptide: Modified GRF(1-29)
Both versions start with the same foundation: a 29-amino-acid analog of growth hormone-releasing hormone (GHRH) with four amino acid substitutions at positions 2, 8, 15, and 27. These substitutions were specifically chosen to resist DPP-IV (dipeptidyl peptidase IV), the enzyme that rapidly degrades native GHRH and its analogs like sermorelin.
The base peptide — sometimes called Modified GRF(1-29) or “Mod GRF” — binds the GHRH receptor on pituitary somatotroph cells and triggers growth hormone release through cAMP/PKA signaling. Same receptor, same pathway as the body’s own GHRH. Half-life: approximately 30 minutes.
What DAC Does
That’s the difference: ~30 minutes vs ~6-8 days. Two orders of magnitude.
Why This Changes Everything
With DAC: Sustained GH Elevation
The extended half-life means CJC-1295 with DAC maintains elevated GH levels continuously over days. This produces a fundamentally different GH profile than normal physiology:
- Non-pulsatile: Rather than amplifying natural GH pulses, it creates sustained, above-baseline GH levels
Without DAC: Amplified Natural Pulses
The no-DAC version clears within hours, which means it amplifies GH pulses during its active window without overriding the body’s natural pulsatile pattern:
- Pulsatile: GH release follows the natural pulse pattern, just with bigger bursts
- Physiological rhythm preserved: Trough periods between pulses are maintained
When to Use Which
- Studying pulsatile GH biology: No DAC. The pulsatile profile preserves the physiological rhythm researchers need to study.
The Pulsatility Question: Why It Matters
This isn’t a minor technical detail. Pulsatile and sustained GH exposure produce measurably different biological effects:
- Pulsatile GH preferentially activates STAT5b signaling → sexually dimorphic gene expression
- Sustained GH produces different liver gene expression profiles
- Body composition effects may differ between pulsatile and continuous GH profiles
- Lipolysis responses vary with GH pattern
Product Specifications
CJC-1295 No DAC (Modified GRF 1-29)
- Molecular Weight: 3,367.97 g/mol
- Half-life: ~30 minutes
- CAS Number: 863288-34-0
- Purity: ≥99% (verified by HPLC)
CJC-1295 with DAC
- Molecular Weight: ~3,647.28 g/mol (including DAC)
- Half-life: ~6-8 days (albumin-bound)
- CAS Number: 863288-34-0 (base peptide)
- Purity: ≥99% (verified by HPLC)
Key References
- Teichman SL, et al. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295. J Clin Endocrinol Metab. 2006;91(3):799-805.
- Ionescu M, Bhatt DL, et al. Pharmacokinetics of CJC-1295 and its effects on GH and IGF-I. J Clin Endocrinol Metab. 2006.