CJC-1295 With DAC vs Without DAC: The Research Difference.

The difference between CJC-1295 with DAC and CJC-1295 without DAC is one chemical group. The DAC (Drug Affinity Complex) is a maleimidopropionic acid unit on the C terminus that binds serum albumin in the bloodstream, and in published pharmacokinetic work it extends the half-life of the GHRH analog from minutes to days. The no-DAC form, usually called Mod GRF 1-29, has the same stabilized peptide backbone but clears quickly and is studied for pulsatile GH signaling. Everything below is drawn from the peer-reviewed record and is framed for in vitro research use only.

What is CJC-1295?

CJC-1295 is a tetrasubstituted analog of human growth hormone-releasing factor, hGRF(1-29), the first 29 amino acids of native GHRH(1-44). Jetté and colleagues (2005) describe it in Endocrinology as "a tetrasubstituted form of hGRF(1-29) with an added N epsilon-3-maleimidopropionamide derivative of lysine at the C terminus." The four substitutions, as reported in the developer and review literature, are D-alanine at position 2, glutamine at position 8, alanine at position 15 and leucine at position 27. Position 2 is the one that matters most for stability: native GHRH is cleaved between residues 2 and 3 by dipeptidyl peptidase-IV (DPP-IV), and Frohman and colleagues (1986) showed in human plasma that the resulting GRH(3-44) fragment retains less than one thousandth of the parent peptide's biological activity. Swapping in a D-amino acid at position 2 blocks that cut. The other three substitutions address chemical stability rather than enzymatic cleavage. Jetté et al. confirmed that the substituted, albumin-conjugated peptide showed "enhanced in vitro stability against dipeptidylpeptidase-IV" and remained bioactive in a GH secretion assay on cultured rat anterior pituitary cells.

What is the DAC in CJC-1295?

DAC stands for Drug Affinity Complex, the developer's name for a reactive maleimide group placed on the peptide so that it bonds to albumin once in circulation. Chemically it is a 3-maleimidopropionic acid unit linked through the side chain of a C-terminal lysine. The maleimide reacts with the one free thiol on serum albumin, cysteine 34, forming a covalent bond. From that point the small peptide travels on a 66 kDa carrier protein, which protects it from renal filtration and from proteases. Jetté et al. (2005) demonstrated this directly: a Western blot of plasma from a rat injected with CJC-1295 showed a CJC-1295 immunoreactive band at the molecular weight of serum albumin, appearing within 15 minutes and still present beyond 24 hours. The same paper reports the peptide detectable in rat plasma beyond 72 hours. The DAC does not change which receptor the peptide binds. It changes how long the peptide stays in circulation to bind it.

What does Mod GRF 1-29 mean?

Mod GRF 1-29 is shorthand for "modified GRF(1-29)", meaning the tetrasubstituted hGRF(1-29) backbone described above without the C-terminal maleimide group. Some suppliers list it as CJC-1295 no DAC or CJC-1295 without DAC; the names refer to the same molecule. The unmodified parent, GRF(1-29) amide, is the sequence also known as sermorelin, and Esposito and colleagues (2003) note in their review that it "maintains bioactivity in vitro and is almost equally effective in eliciting secretion of endogenous growth hormone in vivo" compared with full-length GHRH. Mod GRF 1-29 keeps the DPP-IV resistance conferred by the position-2 substitution but has nothing anchoring it to albumin, so it is cleared roughly as fast as the parent GRF(1-29) once it reaches plasma.

How do CJC-1295 with DAC and without DAC differ in published pharmacokinetics?

The DAC form has a human phase-1 pharmacokinetic study; the no-DAC form is characterized by the GRF(1-29) literature. Teichman and colleagues (2006), publishing in the Journal of Clinical Endocrinology and Metabolism, ran two randomized, placebo-controlled, double-blind ascending-dose trials of CJC-1295 with DAC in healthy adults aged 21 to 61. After a single subcutaneous administration they observed dose-dependent increases in mean plasma GH concentration that persisted for six days or more and increases in mean plasma IGF-I that lasted 9 to 11 days. The estimated half-life of CJC-1295 with DAC was 5.8 to 8.1 days. The abstract describes the GH response as "sustained" rather than pulsatile, which is the expected consequence of a GHRH agonist that never leaves circulation.

For the no-DAC backbone, the relevant numbers come from GRF(1-29) itself. Rafferty and colleagues (1985) measured immunoreactive hGRF(1-29)NH2 in rat plasma after intravenous injection and fitted a biphasic disappearance curve with a distribution half-life of 1.9 minutes and an elimination half-life of 10.4 minutes. They also found that after subcutaneous injection the estimated total amount reaching the circulation was only 4 percent of the intravenous figure, pointing to substantial degradation at or near the injection site. Esposito et al. (2003) summarize the human picture as a plasma half-life of "about 10-20 min in humans," attributed to renal ultrafiltration and N-terminal enzymatic degradation. Mod GRF 1-29 removes the enzymatic route but not the renal one, so it remains a minutes-scale peptide. Jetté et al. (2005) captured the contrast in the same rat model: the unconjugated hGRF(1-29) produced an acute GH pulse, while CJC-1295 produced a four-fold larger GH area under the curve over two hours and stayed measurable for days.

How do the two forms compare side by side?

Dimension	CJC-1295 with DAC	CJC-1295 without DAC (Mod GRF 1-29)
Chemical modification	Tetrasubstituted hGRF(1-29) plus C-terminal lysine-linked 3-maleimidopropionamide that binds albumin Cys34	Tetrasubstituted hGRF(1-29) only; no albumin-binding group
Studied half-life	5.8 to 8.1 days, human phase-1 PK (Teichman 2006); detectable beyond 72 h in rats (Jetté 2005)	Parent GRF(1-29): 10.4 min elimination in rats (Rafferty 1985); about 10 to 20 min in humans (Esposito 2003)
GH release pattern studied	Sustained elevation of GH and IGF-I over days	Acute, transient pulse; studied for pulsatile GH signaling
Typical research pairing	Usually studied alone	Paired with ipamorelin, a GHRP-class secretagogue acting at a different receptor
What the NLL certificate reports	Identity by LC-MS, purity by HPLC, quantity per vial; lot CJWD09080 at 99.76%	Identity by LC-MS, purity by HPLC, quantity per vial; blend lot PS07-CJIP10 at 99.46%

Why is CJC-1295 without DAC paired with ipamorelin in research?

Because the two peptides act on different receptors and clear on a similar timescale. CJC-1295 in either form is a GHRH-receptor agonist acting on pituitary somatotrophs through the cAMP pathway. Ipamorelin is a pentapeptide from a different class entirely. Raun and colleagues (1998) introduced it in the European Journal of Endocrinology as "the first selective growth hormone secretagogue," a GHRP-class compound that released GH from primary rat pituitary cells with potency comparable to GHRP-6, and that in anaesthetized rats and conscious swine did so without raising ACTH, cortisol, FSH, LH, prolactin or TSH beyond what GHRH stimulation produced. GHRP-class secretagogues act at the ghrelin receptor, GHS-R1a, not the GHRH receptor. A GHRH analog and a ghrelin-receptor agonist therefore give researchers two independent inputs into the same GH-release circuit, and the short-acting no-DAC form is chosen so that both inputs rise and fall together rather than one persisting for a week. That is the rationale behind the combined CJC-1295 + Ipamorelin research blend, which NLL lists under Recovery. The albumin-bound CJC-1295 with DAC sits in the same Recovery category as a single compound and is generally studied on its own, since its sustained profile has no reason to be synchronized with a minutes-scale partner. Related GH-axis compounds are listed under Anabolic.

What does the certificate of analysis show for each form?

Each NLL lot ships with a third-party certificate of analysis reporting three things: identity by mass spectrometry (LC-MS), which confirms the observed mass matches the expected sequence; purity by HPLC, expressed as the percentage of the chromatogram attributable to the target peptide; and quantity, the measured amount of peptide per vial. For CJC-1295 with DAC, the identity test is the more informative of the two forms, because the maleimidopropionamide-lysine addition shifts the expected mass relative to Mod GRF 1-29. A certificate that reports the Mod GRF 1-29 mass on a vial labelled DAC, or vice versa, is describing a different molecule.

According to the published COA ledger, the current CJC-1295 with DAC lot, CJWD09080, was analyzed by MDx BioAnalytical and reports 99.76% HPLC purity, with the certificate dated May 20, 2026. The current CJC-1295 + Ipamorelin lot, PS07-CJIP10, was analyzed by ILS Laboratories and reports 99.46% purity, with the certificate dated August 11, 2026. Both signed PDFs are on the Lab Reports page, and the lot number printed on the vial should match the lot on the certificate exactly. For a walkthrough of each line on those reports, including how to check that the identity mass corresponds to the DAC or no-DAC sequence, see how to read a peptide COA.

Frequently asked questions

What does DAC stand for in CJC-1295?

DAC stands for Drug Affinity Complex. In CJC-1295 it is a maleimidopropionamide group on a C-terminal lysine that reacts with the free thiol on cysteine 34 of serum albumin. Jetté and colleagues (2005) showed the albumin-bound peptide remained detectable in rat plasma beyond 72 hours, which is the entire reason the DAC form circulates far longer than the unmodified GRF(1-29) backbone.

Is CJC-1295 without DAC the same as Mod GRF 1-29?

Yes, in common usage. Mod GRF 1-29 is the tetrasubstituted GHRH(1-29) peptide with the four stabilizing amino acid substitutions but without the C-terminal albumin-binding group. It is what suppliers mean by CJC-1295 no DAC. Because nothing anchors it to albumin, it is cleared on the minutes timescale reported for GRF(1-29) analogs rather than the days reported for the DAC form.

How long is the half-life of CJC-1295 with DAC versus without DAC?

In the phase-1 pharmacokinetic study by Teichman and colleagues (2006), the estimated half-life of CJC-1295 with DAC in healthy adults was 5.8 to 8.1 days. The no-DAC backbone is not covered by that paper, but GRF(1-29) itself shows an elimination half-life of about 10 minutes in rats and roughly 10 to 20 minutes in humans, so the two forms differ by a factor of hundreds.

Why is CJC-1295 without DAC paired with ipamorelin in research?

The two act on different receptors. CJC-1295 is a GHRH-receptor agonist, while ipamorelin is a pentapeptide growth hormone secretagogue of the GHRP class, which acts at the ghrelin receptor (GHS-R1a). Raun and colleagues (1998) described it as selective for GH release in rat and swine models. Researchers studying pulsatile GH signaling pair the short-acting no-DAC form with ipamorelin so both inputs rise and clear on a similar timescale.

For in vitro research use only. Not for human consumption. Not evaluated by the FDA. Not intended to diagnose, treat, cure, or prevent any condition. This article summarizes published research and is not medical advice.