CJC-1295 With DAC vs No DAC: What Is the Difference?

10 minute read

What Is the Difference Between CJC-1295 With DAC and No DAC?

CJC-1295 with DAC carries an extra chemical group designed to latch on to a blood protein, so it persists for days. Material sold as CJC-1295 no DAC has no such group. They are two different molecules with almost the same name.

The confusion is not the buyer’s fault. Both forms are built on the same 29-amino-acid backbone, both are sold under the label CJC-1295, and the published human evidence describes only one of them. The table below is the short answer; the sections after it show how each row can be checked.

What Does DAC Mean in CJC-1295?

DAC stands for Drug Affinity Complex. It is a maleimide-containing group bolted to the end of the peptide, and its job is to react with a single sulfur atom on a protein already circulating in blood. That reaction is the whole persistence strategy.

The target is cysteine-34 on serum albumin. Albumin is the most abundant protein in blood plasma, and cysteine-34 is the one position on it carrying a free thiol — a sulfur-hydrogen pair reactive enough to form a bond. A maleimide group is chosen because it reacts with such thiols quickly and selectively.

Jetté and colleagues described exactly this in 2005. They synthesised three maleimide derivatives of human GRF(1-29), joined them to human serum albumin outside the body, and reported that all three stayed active in a growth-hormone secretion assay using cultured rat pituitary cells. Their best compound was named CJC-1295: a tetrasubstituted GRF(1-29) — four of its amino acids swapped for others — with an added lysine at the tail carrying a 3-maleimidopropionamide group.

Why Bind to Albumin at All?

Albumin binding buys time. A small peptide is cleared from blood within minutes, partly by filtration at the kidney and partly by enzymes. Albumin is large, long-lived and not filtered, so a peptide riding on it is shielded from both routes.

The enzyme that matters most here is dipeptidyl peptidase-IV, which clips two amino acids off the front of GHRH-family peptides. The 2005 work reported that the albumin conjugates — the peptide joined to albumin — showed enhanced stability against it in vitro, meaning in glassware rather than in a living subject. Note the wording: the paper reports improved stability, not immunity. That is the second half of the design, the albumin attachment slowing clearance while the backbone substitutions slow the enzyme.

Chapter and colleagues place this in its wider setting. Their 2010 review of chemical modification of class II receptor ligands treats albumin conjugation as one of a family of strategies for making short-lived neuroendocrine peptides last. Amino-acid substitution and fatty-acid attachment are two of the others.

What Did the Human CJC-1295 Study Report?

Teichman and colleagues reported an estimated half-life for CJC-1295 of 5.8 to 8.1 days in healthy adults in 2006. That figure describes the DAC form and nothing else, and it is the single most quoted number in this whole subject.

The study was two randomised, placebo-controlled, double-blind ascending trials, of 28 and 49 days, in healthy adults aged 21 to 61. After a single subcutaneous injection, mean plasma growth hormone rose two- to ten-fold for six days or more, and mean IGF-I rose 1.5- to three-fold for nine to eleven days. After repeated injections, mean IGF-I stayed above baseline for as long as 28 days. No serious adverse reactions were reported.

Is CJC-1295 No DAC the Same Molecule?

No. CJC-1295 no DAC is a different molecule from CJC-1295 with DAC, not a different preparation of one molecule. The two differ by one whole amino acid and one attached chemical group, and the difference is visible in the molecular formula.

PubChem publishes both. The no-DAC structure is C152H252N44O42 at 3367.9, and the DAC-bearing structure is C165H269N47O46 at 3647.2. Subtracting one from the other leaves C13H17N3O4.

That remainder is not an approximation. One lysine residue — one amino-acid unit inside a chain — is C6H12N2O and one 3-maleimidopropionyl group is C7H5NO3; added together they are exactly C13H17N3O4, weighing 128.17 and 151.12 for a total of 279.29. Add that to 3367.9 and the result is 3647.2, which is the published weight of the DAC form to the decimal. The arithmetic can be repeated from the two database pages in under a minute.

One Database Record Carries Both Names

PubChem record CID 56841945 holds the structure of the no-DAC peptide while simultaneously listing “CJC 1295 with DAC” among its names. One record, two molecules, and it is the clearest illustration available of why a product name proves nothing about a structure.

The record was read directly from PubChem’s programmatic interface on 2 September 2026. Its structure fields describe a chain of 29 residues ending in argininamide, formula C152H252N44O42, weight 3367.9. Its InChIKey, the fingerprint string a structure hashes to, is XOZMWINMZMMOBR-HRDSVTNWSA-N. There is no maleimide in that structure and no thirtieth residue. Its synonym list, however, contains all of the following.

The last row is the sharpest of the five. The record carries a sequence string of thirty letters whose final lysine bears a maleimidopropionyl group, sitting beside a structure of twenty-nine residues that has neither. A reader who searches PubChem for CJC-1295 by name is sent somewhere else again, to record CID 91971820, which does hold the 30-residue DAC form under a third CAS number.

Is Modified GRF (1-29) the Same as Natural GHRH (1-29)?

Modified GRF (1-29) is related to natural GHRH (1-29) but is not identical to it. Four of the twenty-nine positions have been swapped deliberately, which is what the word modified is recording, and the substitutions can be read straight off the public structures.

Aligning PubChem’s systematic name for the no-DAC peptide against its systematic name for sermorelin — the pharmaceutical form of GHRH (1-29) — puts the four differences at positions 2, 8, 15 and 27.

The last swap leaves a fingerprint anyone can check. Methionine is the only sulfur-carrying amino acid in GHRH (1-29), so sermorelin’s formula ends in an S — C149H246N44O42S. Replace it with leucine and the sulfur disappears, which is why the modified peptide’s formula has none.

The two formulas differ by C3H6 gained and one sulfur lost, which is all four substitutions together and not the position 27 swap on its own. Three of the four add a single CH2 each — asparagine to glutamine, glycine to alanine, methionine to leucine — while the D-alanine at position 2 is the mirror image of the alanine it replaces and changes no atom count at all. The net result is ten units heavier: 3367.9 against sermorelin’s 3357.9.

Position 2 is the one that changes behaviour most. Dipeptidyl peptidase-IV clips the first two residues off this family of peptides, and a D-amino acid there is not the shape the enzyme is built to cut. That is a general property of D-amino acid substitution rather than a measurement on this peptide; the 2010 review lists it among the modification strategies used across this receptor family. The swap at 27 removes the molecule’s only sulfur atom, which is checkable from the two formulas above. How sequence differences of this size change a molecule’s identity is covered in peptide types, categories and blends.

Does CJC-1295 No DAC Have a Published Half-Life?

No verified human half-life for supplier-labelled Modified GRF (1-29) is established by any of the papers cited on this page. Numbers of around thirty minutes circulate widely on retail sites, and none of the sources listed below supports one.

This is a gap in the evidence rather than a secret. CJC-1295 with DAC was taken into human trials by its developer and Modified GRF (1-29) was not. So one form has a published profile of how it is absorbed and cleared, and the other does not. Anyone quoting a duration for no-DAC material should be asked which study measured it, in which species, and in how many subjects.

Where Does Ipamorelin Fit?

Ipamorelin is not a GHRH analogue at all, so the DAC question does not arise for it. An analogue is a molecule built on the structure of another; ipamorelin is built on nothing of the sort. It is a growth hormone secretagogue — a compound that prompts a gland to release something it already makes — and it is five amino acids long, acting at a different receptor from the one CJC-1295 acts on. There is no DAC version of ipamorelin.

Raun and colleagues characterised it in 1998, describing it as the first selective growth hormone secretagogue. Working in cultured rat pituitary cells, in rats and in conscious swine, they used receptor antagonists to establish that it releases growth hormone through a GHRP-like receptor rather than the GHRH receptor. In swine it did not raise ACTH or cortisol above the levels seen after GHRH stimulation.

That receptor difference is the reason the two peptides are studied as a pair rather than as substitutes. They reach the same gland by separate routes.

Which Form Does ARP List?

Australian Research Peptides lists the no-DAC form, blended with ipamorelin in a single vial as CJC-1295 (no DAC) + Ipamorelin at 10 mg, currently available to order. There is no DAC-modified listing in the catalogue.

A batch certificate is published for this vial, and it reports identity and amount rather than a single purity percentage. That is normal for a multi-component vial: one figure cannot describe two peptides, so the laboratory reports each component instead. Certificates are listed in the certificate library, which shows the current state for every product and strength. The laboratory’s own name is printed on each document.

Ipamorelin is also catalogued on its own as a single-peptide listing, for anyone comparing a blend against separate vials. Everything on this page is supplied for in vitro research purposes only.

Claim, Evidence and Boundary

The load-bearing statements on this page are set out below with the evidence behind them and the limit of what that evidence covers. Where a sentence elsewhere on the page states general peptide chemistry rather than a result from one of these sources, it says so in place.

Related Guides

• Tesamorelin: a GHRH analogue explainedAnother modified GHRH peptide, and what its trials actually measured.
• Peptide testing, purity & CoAsHow a certificate establishes what is in a vial, and what it leaves unanswered.
• Peptide types, categories & blendsWhy one changed amino acid makes a different molecule, and how a blend is stated.
• Lyophilised peptides: storage & handlingWhy research peptides arrive freeze-dried, and what keeps the powder stable.

Of the two forms compared here, Australian Research Peptides catalogues the no-DAC peptide only, paired with ipamorelin in one vial under Growth Hormone Research, orderable today with its batch certificate published, and dispatches it from Sydney across Australia.

Read this article as plain text — CJC-1295 With DAC vs No DAC: What Is the Difference?, in Markdown — the full text in Markdown, without the page around it, for assistants, screen readers and offline reading.