CJC-1295 Research Guide: DAC vs No-DAC Explained

The single most important thing to understand about CJC-1295 is that “CJC-1295” refers to two related but meaningfully different research compounds, and confusing them is the most common mistake in study design. Both are analogs of growth-hormone-releasing hormone (GHRH), and both are used in preclinical work to stimulate the pituitary side of the growth-hormone axis. The difference sits in one structural feature, the Drug Affinity Complex (DAC), and that feature changes how long the peptide persists in research models by an order of magnitude. If you are sourcing this peptide for laboratory study, knowing which version you have is not a detail. It defines the experiment.

This guide covers what CJC-1295 is, how the DAC and no-DAC forms differ and why that changes half-life, the GH and IGF-1 mechanisms researchers study, why it so often appears alongside ipamorelin, and the handling and quality questions that keep your data interpretable.

What is CJC-1295?

CJC-1295 is a synthetic peptide modeled on GHRH, the hypothalamic hormone that signals the pituitary to release growth hormone. Native GHRH is a 44-amino-acid peptide, but its biological activity lives in the first 29 residues. That fragment, GHRH(1-29), is the functional core and the starting point for the CJC-1295 family.

The problem with the raw 1-29 fragment is that it breaks down almost immediately. An enzyme called dipeptidyl peptidase-4 (DPP-4) clips it near the N-terminus within minutes, so on its own it is a poor tool for all but the shortest experiments. The CJC-1295 modifications exist to solve that fragility, and the two versions solve it to very different degrees.

The two versions: DAC and no-DAC

Both forms start from a modified GHRH(1-29) backbone carrying a handful of amino acid substitutions. Those substitutions protect the peptide from the enzymatic cleavage that destroys unmodified GHRH(1-29). This modified backbone, on its own, is the no-DAC version, which goes by several names in supplier catalogs and the literature: CJC-1295 without DAC, CJC-1295 no-DAC, and most precisely Mod GRF 1-29 (modified GRF 1-29). All refer to the same stabilized GHRH(1-29) analog with no DAC attached.

The DAC version adds one more component. DAC, the Drug Affinity Complex, is a small chemical group (a maleimidopropionic acid moiety) bonded to the peptide. Once in circulation in a research model, that group reacts with albumin, the most abundant protein in blood, and binds the peptide to it. Albumin is a large, long-lived carrier protein, so tethering the peptide to it shields the molecule from clearance and keeps it in circulation far longer. The naming resolves cleanly once you see the logic: Mod GRF 1-29 is the stabilized backbone, and CJC-1295 DAC is that same backbone plus the albumin-binding complex.

Why does DAC change the half-life?

This is the practical crux. The two versions produce very different exposure profiles in research models, and the DAC is the reason.

Unmodified GHRH(1-29) is cleared in minutes. The Mod GRF 1-29 (no-DAC) backbone, protected against DPP-4 cleavage, persists longer but is still relatively short-acting, which in study terms means it produces a brief, pulse-like stimulation of the pituitary before it clears. The DAC version, bound to albumin, persists dramatically longer, extending the functional presence of the peptide from the range of hours into a range measured in days.

That difference shapes what each form is good for. A short-acting analog like Mod GRF 1-29 tends to be studied where researchers want a discrete, time-limited GH stimulus that mimics the pulsatile way the axis naturally fires. The long-acting DAC version produces a sustained elevation in GHRH signaling, raising the baseline of axis stimulation rather than delivering a sharp pulse. Neither is inherently better; they are different experimental tools, and half-life is what separates them. Reported timeframes vary with model, assay, and dose, so treat any specific number with the caution you would apply to any preclinical parameter.

Mechanisms studied: the GH and IGF-1 axis

CJC-1295 is a probe for the GHRH arm of the growth-hormone axis, a cascade in which the hypothalamus releases GHRH, the pituitary responds by secreting growth hormone (GH), and GH drives the liver and other tissues to produce insulin-like growth factor 1 (IGF-1). Feedback from GH and IGF-1 then modulates the upstream signals.

As a GHRH analog, CJC-1295 acts at the top of that cascade, binding GHRH receptors on pituitary somatotroph cells and prompting GH release. Preclinical studies using this class of compound typically measure circulating GH, downstream IGF-1, receptor binding and activation, or the pattern of GH secretion over time. Because the DAC and no-DAC forms differ so sharply in duration, they let researchers ask distinct questions with the same underlying mechanism: the short-acting analog suits the study of pulsatile release, while the long-acting form suits the study of sustained GHRH receptor stimulation. That distinction matters because the natural axis does not run at a constant level, and the two forms let a study model either mode.

Why is CJC-1295 often paired with ipamorelin?

In research designs and supplier listings, CJC-1295 turns up next to ipamorelin so often that the pairing is almost a default. The reason is mechanistic. The growth-hormone axis has two stimulatory inputs into the pituitary: the GHRH pathway and the ghrelin pathway. CJC-1295 acts on the GHRH receptor. Ipamorelin acts on the ghrelin receptor (GHS-R1a). Because they hit two different receptors that both drive GH release, studies examine them together to look at how simultaneous stimulation of both arms affects growth hormone output compared with either input on its own.

The value in a combined design is that the two mechanisms are independent, so their effects can be studied both separately and together. The discipline that matters is to treat them as two distinct compounds with two distinct receptors, not a single unit, because that distinction governs your controls. When the two are studied together, the short-acting Mod GRF 1-29 is frequently the CJC-1295 form of choice, since pairing a pulse-like GHRH stimulus with a ghrelin-receptor agonist lets a study probe coordinated, pulsatile release rather than a flat elevation.

Research forms: lyophilized powder

CJC-1295, in both DAC and no-DAC forms, is supplied for research as a lyophilized (freeze-dried) powder in a sealed vial, usually labeled by peptide mass in milligrams. Freeze-drying removes water and leaves the peptide in a stable solid, which is how a molecule that would degrade quickly in solution can be shipped and stored. The powder is not ready to use as received. It has to be reconstituted before any bench application, and the care taken at that step determines the stability of the solution for the rest of the vial’s life.

Handling, reconstitution, and storage

Clean data depends on disciplined handling. The practices below apply broadly to lyophilized research peptides, both CJC-1295 forms included:

• Store the sealed, unopened vial cold. Lyophilized powder is generally refrigerated for short-term holding and frozen for longer-term storage, kept away from light and moisture.

• Let a cold vial warm to room temperature before opening, so condensation does not form inside the vial.

• Reconstitute with an appropriate sterile solvent, commonly bacteriostatic or sterile water, added slowly down the inner wall of the vial rather than squirted directly onto the powder. Swirl gently to dissolve, and do not shake hard, because mechanical agitation and foaming degrade peptides.

• Once reconstituted, keep the solution refrigerated and shielded from temperature swings. Peptide in solution is far less stable than the dry powder and has a much shorter usable window.

• Minimize freeze-thaw cycles. Each cycle is a chance for degradation, so aliquoting a stock lets you avoid thawing the whole supply repeatedly.

The principle behind all of it is simple: the dry lyophilized form is the stable state, and every step that adds water, heat, light, or agitation moves the peptide toward breakdown.

Quality markers: purity and the COA

A vial is only as trustworthy as its manufacturing and verification, and research buyers should be demanding here. Two markers carry most of the weight.

Purity is typically reported as a percentage from high-performance liquid chromatography (HPLC), which separates the target peptide from related impurities and truncated sequences. This matters more than usual for CJC-1295, because the DAC and no-DAC forms are closely related and the modifications are subtle. A high HPLC purity figure indicates that most of what is in the vial is the intended peptide rather than synthesis byproducts or the wrong variant.

The certificate of analysis (COA) is the document that backs those claims. A meaningful COA reports the peptide’s identity, often confirmed by mass spectrometry, which verifies molecular weight, along with the measured purity, the method used, and batch or lot information for traceability. For CJC-1295 the mass-spectrometry identity check is worth extra attention, since the DAC and no-DAC forms have different molecular weights, so a proper identity report is what tells you which one is actually in the vial. A supplier that provides a lot-specific COA, rather than a generic document, lets you tie your results to a verified batch. If a vendor cannot produce a COA for the exact lot you received, treat that as a reason to look elsewhere.

Frequently asked questions

Q. What is the difference between CJC-1295 with DAC and without DAC?

Both are stabilized GHRH(1-29) analogs. The no-DAC version (Mod GRF 1-29) is the modified backbone alone and is relatively short-acting. The DAC version adds a Drug Affinity Complex that binds the peptide to albumin in the blood, which extends its presence in research models from the range of hours into the range of days.

Q. Is CJC-1295 the same as Mod GRF 1-29? 

Mod GRF 1-29 is the no-DAC form of CJC-1295. When a source says “CJC-1295 no-DAC,” “CJC-1295 without DAC,” or “Mod GRF 1-29,” it is referring to the same stabilized GHRH(1-29) analog without the albumin-binding complex.

Q. How does CJC-1295 work?

It is a GHRH analog, so it binds GHRH receptors on the pituitary and stimulates growth hormone release. In the growth-hormone axis, that GH then drives production of IGF-1 in the liver and other tissues, which is why preclinical studies measure both.

Q. Why is CJC-1295 studied with ipamorelin?

The two act on different receptors that both trigger GH release. CJC-1295 works on the GHRH receptor and ipamorelin on the ghrelin receptor, so studies examine them together to see how stimulating both arms of the axis affects growth hormone output compared with either alone.

A note on research use

CJC-1295 and the related peptides discussed here are intended for laboratory and research use only. They are not for human consumption or medical use, and nothing above is dosing guidance or treatment advice.

The one habit that saves the most trouble with this peptide is confirming which version you actually have before you design around it. Read the COA, check the mass-spectrometry identity against the DAC and no-DAC molecular weights, verify HPLC purity, and store the lyophilized powder cold and dry until use. The DAC-versus-no-DAC distinction is the whole story with CJC-1295, and it starts with knowing what is in the vial.