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
The DAC modification adds a reactive chemical group (maleimidopropionic acid) that covalently bonds to serum albumin after administration. Albumin is the most abundant protein in blood and has a half-life of approximately 20 days. By hitching a ride on albumin, CJC-1295 with DAC extends its circulating half-life to approximately 6-8 days.
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
- Elevated IGF-1: The continuous GH stimulation drives sustained IGF-1 production — studies report IGF-1 remaining elevated for 9-11 days after a single administration
- Less frequent dosing: Weekly or even less frequent administration in research protocols
The Teichman et al. (2006) study in the Journal of Clinical Endocrinology & Metabolism demonstrated that a single dose produced dose-dependent GH elevations lasting 6+ days, with corresponding IGF-1 increases persisting even longer.
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
- More frequent dosing: Multiple daily administrations in research protocols
- Synergy with GH secretagogues: Commonly combined with ipamorelin — GHRH amplifies pulse amplitude, the secretagogue increases frequency
When to Use Which
- Studying pulsatile GH biology: No DAC. The pulsatile profile preserves the physiological rhythm researchers need to study.
- Studying sustained GH/IGF-1 elevation: With DAC. Days of continuous stimulation from a single administration.
- Combination protocols: No DAC + ipamorelin is the standard pairing — two independent pathways (GHRH-R + GHS-R1a) producing synergistic GH output.
- Convenience in long-term studies: With DAC requires less frequent administration, simplifying chronic study protocols.
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
Choosing the wrong form for your experiment doesn’t just affect dosing logistics — it can alter the fundamental biology you’re studying.
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.
Browse CJC-1295 No DAC, CJC-1295 with DAC, or the popular CJC-1295 + Ipamorelin combo. All independently tested at Janoshik Analytical.