Research Use Only. The information presented here is for scientific and educational purposes. These compounds are not intended for human consumption, self-administration, or therapeutic use.
Introduction
CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH), built from the first 29 amino acids of the endogenous hormone. In laboratory and preclinical research it is studied as a growth hormone secretagogue that acts on GHRH receptors of the anterior pituitary, prompting the release of growth hormone (GH) and the downstream production of insulin-like growth factor 1 (IGF-1). Two closely related research forms circulate under the same CJC-1295 name, and the distinction between them, the presence or absence of a Drug Affinity Complex (DAC), is one of the most frequently confused points in growth hormone axis research.
The DAC modification does not change which receptor the peptide targets. Instead, it changes how long the molecule persists in circulation, converting a short-acting GHRH analog into a long-acting one and reshaping the entire pattern of GH release. This comparison contrasts CJC-1295 with DAC against CJC-1295 without DAC (often labeled Modified GRF 1-29) across identity, molecular weight, half-life, and secretory profile, presented strictly for research use only, not for human consumption.
What Is CJC-1295 and the Role of DAC?
The Shared GHRH Analog Backbone
Both variants share an identical peptide backbone: a 29 residue sequence derived from native GHRH(1-29), the biologically active fragment of the full 44 residue hormone. To resist enzymatic breakdown, four amino acid substitutions are introduced relative to native GHRH, commonly summarized as D-Ala at position 2, Gln at position 8, Ala at position 15, and Leu at position 27. The position 2 substitution is especially important because it blunts cleavage by dipeptidyl peptidase-4 (DPP-4), the enzyme that rapidly inactivates native GHRH. This tetra-substituted backbone is exactly what researchers call Modified GRF 1-29, and it is the molecule sold as CJC-1295 (No DAC).
What the DAC Group Adds
The Drug Affinity Complex is a small chemical group, based on maleimidopropionic acid, attached through an added lysine residue at the C-terminus. Once in circulation, this reactive group forms a covalent bond with a cysteine residue on serum albumin, the most abundant protein in blood plasma. By tethering to albumin, the peptide is shielded from kidney filtration and enzymatic degradation. The outcome is a bioconjugation strategy (originally developed by ConjuChem) that extends the functional half-life from minutes to days. Without DAC, the peptide carries no albumin anchor and clears quickly.
Identity and Molecular Comparison
The identity values below reflect commonly reported laboratory attributes and are provided for comparison only.
| Attribute | CJC-1295 with DAC | CJC-1295 without DAC (Mod GRF 1-29) |
|---|---|---|
| Class | GHRH analog, GH secretagogue | GHRH analog, GH secretagogue |
| Amino acid residues | 30 (29 plus Lys linker) | 29 |
| Approx. molecular weight | ~3647 g/mol | ~3368 g/mol |
| Key modification | Tetra-substituted plus DAC (albumin binding) | Tetra-substituted only |
| Albumin binding | Yes (covalent) | No |
| Receptor target | GHRH receptor | GHRH receptor |
The added lysine linker and DAC group account for the roughly 279 g/mol difference in molecular weight between the two forms, while the receptor target and core sequence remain unchanged.
Half-Life and Release Kinetics: DAC vs No DAC
The comparative figures below reflect commonly reported laboratory attributes and are provided for comparison only.
| Parameter | With DAC | Without DAC |
|---|---|---|
| Reported plasma half-life | ~6 to 8 days | ~30 minutes |
| GH release pattern | Prolonged, sustained elevation (a “bleed”) | Brief pulse mirroring natural rhythm |
| Re-dosing interval in studies | Infrequent (long interval) | Frequent (short interval) |
| IGF-1 profile | Sustained increase | Transient increase |
| Circulating persistence | Days | Under one hour |
The Long-Acting Profile With DAC
Because albumin binding keeps CJC-1295 with DAC in circulation for days, published pharmacokinetic research has reported that a single exposure can elevate GH and IGF-1 over an extended window. This produces what investigators describe as a GH “bleed”: a sustained, relatively non-pulsatile elevation rather than the sharp peaks of natural secretion. Teichman and colleagues (2006) reported prolonged elevation of GH and IGF-1 following CJC-1295 with DAC in early pharmacology work. This sustained, low-amplitude profile is the defining research characteristic of the DAC variant.
The Pulsatile Profile Without DAC
CJC-1295 without DAC clears within roughly half an hour, so its GH-releasing effect is brief and pulse-like. Investigators studying the physiological importance of GH pulsatility often prefer this shorter-acting form because it more closely mimics the body’s own secretory rhythm, in which GH is released in discrete bursts. That closer match to endogenous kinetics is a key reason the No DAC form remains a common tool in growth hormone axis models.
Research Pairings and Handling Considerations
Combining a GHRH Analog With a Secretagogue
In growth hormone axis research, the shorter-acting CJC-1295 (No DAC) is frequently investigated together with Ipamorelin, a selective growth hormone secretagogue receptor (GHS-R) agonist. The rationale is mechanistic: a GHRH analog increases the pool of GH available for release, while a ghrelin-mimetic secretagogue amplifies the pulse through a complementary pathway. Pre-combined research material such as the CJC-1295 and Ipamorelin blend is studied for this reason. The DAC variant, with its sustained kinetics, is paired this way less often because its release profile differs fundamentally from a discrete pulse.
Handling and Verification
Both variants are supplied as lyophilized powder and reconstituted with bacteriostatic water before laboratory use; the reconstitution guide covers worked concentration examples such as adding 2 mL of bacteriostatic water to a 5 mg vial to yield 2.5 mg/mL. As with any research peptide, identity and purity should be confirmed against a certificate of analysis. Learning how to read a peptide COA helps a researcher verify that a “with DAC” or “no DAC” label matches the molecular weight reported by mass spectrometry, since the roughly 279 g/mol gap between the forms is the clearest analytical fingerprint of which variant is in the vial. A full catalog of related GH axis materials is available in the research peptides shop.
Frequently Asked Questions
What is the main difference between CJC-1295 with DAC and without DAC?
The two forms target the same GHRH receptor and share the same peptide backbone, but the DAC version carries a Drug Affinity Complex that binds serum albumin and extends its half-life from roughly 30 minutes to several days. The result is a sustained, non-pulsatile pattern of growth hormone release with DAC, versus a brief pulse without it.
Is CJC-1295 without DAC the same as Modified GRF 1-29?
Yes. CJC-1295 without DAC is chemically identical to Modified GRF 1-29 (sometimes written Mod GRF 1-29), a tetra-substituted analog of GHRH(1-29). The two names refer to the same 29 amino acid research peptide.
Why does the DAC version last so much longer?
The DAC group forms a covalent bond with albumin, the most abundant protein in blood plasma. By anchoring to albumin, the peptide resists rapid kidney filtration and enzymatic breakdown, which is why its reported half-life is measured in days rather than minutes.
Which version is studied with Ipamorelin?
The shorter-acting CJC-1295 (No DAC) is the form most commonly studied alongside Ipamorelin, because its pulse-like GH release pairs mechanistically with a selective secretagogue. This pairing is also available pre-combined as the CJC-1295 and Ipamorelin blend.
How much does molecular weight differ between the two forms?
CJC-1295 with DAC has a reported molecular weight of approximately 3647 g/mol across 30 residues, while the No DAC form (Mod GRF 1-29) is approximately 3368 g/mol across 29 residues. The difference reflects the added lysine linker and DAC group.
Does the DAC modification change the receptor target?
No. Both variants act on the same GHRH receptor of the anterior pituitary. The DAC modification alters pharmacokinetics, meaning how long the peptide persists in circulation, not the receptor it engages.
References and Further Reading
- Teichman SL, et al. (2006). Prolonged stimulation of growth hormone and IGF-I secretion by CJC-1295, a long-acting GHRH analog. PubMed: CJC-1295 growth hormone
- Research on DAC albumin bioconjugation of GRF analogs (ConjuChem technology). PubMed: CJC-1295 DAC albumin
- Frohman LA and colleagues on GHRH physiology and pulsatile GH secretion. PubMed: GHRH pulsatile growth hormone
- GHRH receptor signaling in the anterior pituitary. PubMed: GHRH receptor pituitary
- Dipeptidyl peptidase-4 and enzymatic degradation of GHRH. PubMed: GHRH dipeptidyl peptidase
- Ipamorelin and growth hormone secretagogue receptor research. PubMed: ipamorelin growth hormone secretagogue
- Overview of the growth hormone and IGF-1 axis. PubMed: growth hormone IGF-1 axis
