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CJC-1295 With DAC vs Without DAC: Structural and Research Comparison for UK Laboratory Research
CJC-1295 With DAC and CJC-1295 Without DAC are two distinct research compounds built on the same structural foundation: a tetrasubstituted, 29-amino-acid analogue of the biologically active fragment of human Growth Hormone-Releasing Hormone (GHRH). This page compares them directly — the exact structural modification that separates them, what that modification does mechanistically, and the research-relevant consequences for pharmacokinetics and experimental design. It is a companion to the site’s existing CJC-1295 Without DAC research guide, not a replacement for it.
Both variants are supplied for in-vitro and preclinical laboratory research only. Neither is licensed by the MHRA as a medicinal product, and no dosing or administration guidance is provided in this guide or in any Ascend Peptides UK documentation. Both compounds are supplied for use by laboratories, academic institutions and research scientists studying GHRH receptor pharmacology and growth hormone axis signalling.
Every batch of CJC-1295 supplied by Ascend Peptides UK — With DAC and Without DAC — is HPLC verified at ≥98% purity by Janoshik laboratory, LC-MS confirmed for molecular identity, and accompanied by a publicly verifiable Certificate of Analysis.
What Is CJC-1295? A Note on Naming
The name “CJC-1295” is a useful place to start, because the commercial research-chemical naming convention and the original scientific literature do not use it in quite the same way, and researchers should be aware of the distinction.
In the original characterisation literature, “CJC-1295” refers specifically to the albumin-binding, long-acting molecule — the tetrasubstituted GRF(1-29) analogue conjugated to a Drug Affinity Complex (DAC) — first structurally described by Jette et al. (2005) and pharmacokinetically characterised in humans by Teichman et al. (2006). In that literature, the unconjugated parent peptide (the tetrasubstituted GRF(1-29) analogue before DAC conjugation) is generally referred to as Modified GRF(1-29) or Mod GRF(1-29), tracing back to the earlier structural work on stabilised GRF(1-29) analogues by Campbell et al. (1991).
The research-chemical marketplace, including this page, uses “CJC-1295 Without DAC” as a retronym for that same parent compound — Modified GRF(1-29) — to make its relationship to the DAC-conjugated molecule explicit for buyers comparing the two. This is now the standard industry convention, but it is a naming convention, not evidence that the specific material sold commercially as “CJC-1295 Without DAC” was itself the subject of the published DAC-era human trials. The human studies discussed on this page — Teichman et al. (2006) and Ionescu & Frohman (2006) — specifically administered and characterised the DAC-conjugated molecule; neither trial tested the non-DAC parent peptide in humans under any name. The US FDA’s 2024 evaluation of CJC-1295 nominations for the compounding bulk drug substances list treats “CJC-1295 (free base)” and “CJC-1295 (DAC) (free base)” as two distinct active moieties, each with its own chemical structure and pharmacokinetic profile, rather than as interchangeable forms of a single studied compound. We present this distinction directly: commercial naming and the identity of the compound actually studied in the published DAC trials are two different things, and this page does not conflate them.
The Structural Difference: What DAC Actually Is
Both variants share the same 29-amino-acid tetrasubstituted GRF(1-29) backbone, carrying four amino acid substitutions relative to native human GHRH(1-29) that improve resistance to enzymatic degradation by dipeptidyl peptidase-IV (DPP-IV) and improve receptor-binding stability. Published sequence data confirms at least a D-alanine substitution at position 2 and a glutamine substitution at position 8 relative to native GHRH(1-29); the complete substitution set is documented in the original structural characterisation literature (Campbell et al., 1991; Jette et al., 2005).
The DAC modification is added on top of this shared backbone. DAC stands for Drug Affinity Complex — a C-terminal lysine residue bearing an added maleimidopropionyl group (described in the pharmacological literature as an N-3-maleimidopropionamide derivative of lysine). This reactive maleimide group undergoes bioconjugation in vivo to the free thiol (sulfhydryl) group on cysteine-34 of circulating serum albumin. The result is that the DAC-modified peptide becomes covalently tethered to a circulating albumin molecule shortly after entering the bloodstream, rather than remaining a free, rapidly cleared peptide (Jette et al., 2005).
CJC-1295 Without DAC lacks this maleimide-lysine extension entirely — it is the tetrasubstituted GRF(1-29) backbone on its own, with no albumin-binding mechanism. That single structural difference — presence or absence of the DAC extension — is what separates the two compounds and drives every downstream pharmacokinetic difference discussed below.
The molecular formulas and masses given below describe the free-base active moiety of each compound. They do not necessarily describe the exact lyophilised salt or counterion form supplied in a vial — the FDA’s 2024 evaluation of CJC-1295 nominations for the compounding bulk drug substances list treats free-base, acetate, and TFA (trifluoroacetate) forms as distinct bulk drug substances, each with its own chemical structure and physicochemical properties, because a salt form is not simply an alternative label for the same free-base entity.
|
Property |
CJC-1295 With DAC |
CJC-1295 Without DAC |
|---|---|---|
|
Also known as |
CJC-1295 (as named in the original 2005–2006 characterisation literature) |
Modified GRF(1-29); Mod GRF 1-29 (commercial/research-chemical retronym) |
|
Structural basis |
Tetrasubstituted GRF(1-29) analogue + C-terminal DAC (maleimidopropionyl-lysine) extension |
Tetrasubstituted GRF(1-29) analogue only — no DAC extension |
|
Molecular formula (free-base active moiety) |
C165H269N47O46 |
C152H252N44O42 |
|
Molecular mass (free-base active moiety) |
≈ 3,647.2 Da |
≈ 3,368 Da |
|
Albumin-binding mechanism |
Yes — covalent bioconjugation to Cys-34 of serum albumin via the DAC maleimide group |
No — remains a free peptide in circulation |
|
Half-life evidence |
Published human studies report a multi-day terminal half-life (approximately 5–9 days depending on study/analysis) — DAC-specific human evidence (Teichman et al., 2006) |
No directly comparable published human PK value identified for the 29-aa non-DAC active moiety; expected to be substantially shorter-lived, but common ~30-minute claims should not be presented as equivalent-quality evidence |
|
Receptor target |
GHRH receptor (GHRHR) — anterior pituitary somatotroph cells |
GHRH receptor (GHRHR) — anterior pituitary somatotroph cells |
|
Downstream signalling |
Gs-coupled cAMP/PKA cascade |
Gs-coupled cAMP/PKA cascade |
|
Research category |
GH Axis Research Peptide (GHRH analogue, long-acting) |
GH Axis Research Peptide (GHRH analogue, short-acting) |
Reconstitution requirements are product-specific rather than an intrinsic structural difference between the two variants, and are not treated as a comparison point in the table above — see each product listing (CJC-1295 With DAC, CJC-1295 Without DAC) for Ascend Peptides UK’s current handling instructions.
Albumin-Binding and Comparative Persistence
The persistence evidence available for these two variants is not of equal quality, and the table above should not be read as two directly comparable measurements. The FDA’s 2024 evaluation of CJC-1295 nominations for the compounding bulk drug substances list states plainly that direct evidence comparing the half-life of CJC-1295 DAC against CJC-1295 without DAC is lacking, and separately that FDA has not identified nonclinical pharmacokinetic or toxicokinetic studies of CJC-1295 (free base), CJC-1295 acetate, CJC-1295 DAC (free base), or CJC-1295 DAC acetate. No human pharmacokinetic study specifically measuring the 29-amino-acid non-DAC active moiety has been identified for this page either. The widely repeated “~30 minute” half-life figure for CJC-1295 Without DAC in commercial and research-chemical literature should therefore be treated as an unsourced or indirectly-derived estimate, not as data of the same evidentiary standing as the DAC human trial data below — it is not presented on this page as an established measurement.
The published human evidence that does exist is specific to the DAC-conjugated molecule. Teichman et al. (2006) administered a single subcutaneous dose of CJC-1295 With DAC to healthy adult volunteers and reported sustained, dose-dependent elevation of plasma growth hormone (2- to 10-fold above baseline for six days or more) and plasma IGF-1 (1.5- to 3-fold above baseline for nine to eleven days), with an estimated terminal half-life of approximately 5.8 to 8.1 days depending on the specific analysis reported in that study. This is DAC-specific human pharmacokinetic and pharmacodynamic data from a single clinical study, not an exhaustive or repeatedly replicated dataset — it should be read as a documented estimate from that trial, not extrapolated to describe, or compared directly against, the non-DAC form.
GHRH Receptor Signalling: What’s the Same Between Both Variants
Despite their different persistence profiles, both variants are pharmacologically identical at the point of receptor engagement. Both act as selective agonists at the GHRH receptor (GHRHR) on anterior pituitary somatotroph cells, and both trigger the same Gs-protein-coupled cAMP/PKA signalling cascade associated with GH synthesis and secretion in published research models. Neither compound engages a different receptor or a different downstream pathway — the DAC modification changes how long the molecule remains available to engage GHRHR, not which receptor it engages or what happens once it binds.
This is the same receptor pathway studied via the site’s other GHRH analogue research guide, What Is Tesamorelin?, and is mechanistically distinct from the GHS-R1a (ghrelin receptor) pathway covered in What Is Ipamorelin? — relevant context for researchers designing combined GHRH/GHRP protocols.
Pulsatile vs Sustained GH Release: A Closer Look
It is important to keep two different things separate: how long a compound remains available to stimulate the GHRH receptor (a pharmacokinetic property) and the pattern — pulsatile or otherwise — in which the pituitary actually secretes GH in response (a downstream physiological property). A common simplification collapses these into a single claim — that CJC-1295 Without DAC produces “pulsatile” GH release while CJC-1295 With DAC produces “continuous, non-pulsatile” GH release — and that simplification is not supported by the available published evidence.
For CJC-1295 With DAC specifically, Ionescu & Frohman (2006) investigated this question directly and found that pulsatile GH secretion persists even during prolonged, continuous CJC-1295 With DAC stimulation. Prolonged systemic exposure to the DAC-conjugated compound does not flatten GH output into an unvarying continuous elevation — the pituitary retains its underlying pulsatile secretory pattern superimposed on a raised baseline. Prolonged GHRH-receptor stimulation and non-pulsatile GH secretion are not the same thing, and the published data specifically contradicts equating the two.
For CJC-1295 Without DAC, this page does not assert a specific GH secretion pattern, because no study identified for this page directly measures GH secretion dynamics for that specific 29-amino-acid non-DAC molecule. A brief receptor-engagement window associated with rapid clearance is a distinct, structurally-grounded observation from a specific claim about the resulting GH secretion pattern, and the two should not be conflated. Researchers designing pulsatility-sensitive protocols should treat GH-pulsatility data as compound- and study-specific rather than inferring it from persistence data alone.
Similarities Between Both Compounds
Beyond the shared receptor pathway, both variants share several other properties relevant to research design: the same tetrasubstituted GRF(1-29) structural backbone; the same DPP-IV-resistance rationale for the four base substitutions; the same reconstitution requirement (Acetic Acid Water, not standard bacteriostatic water); the same WADA Prohibited List status (Category S2, prohibited at all times); and the same regulatory position in the UK — neither is licensed by the MHRA as a medicinal product, and both are supplied strictly for laboratory research.
Which Variant May Suit Which Research Question?
The structural and pharmacokinetic differences above translate into different research applications, independent of any human-use context:
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Researchers investigating natural, episodic GH secretion dynamics, GHRHR binding kinetics in short-timeframe assays, or comparative studies against native GHRH and other short-acting analogues (such as Sermorelin) may find the Without DAC variant’s brief receptor-engagement window more relevant to the physiological process being modelled.
-
Researchers investigating sustained GHRHR occupancy, longer-duration downstream signalling consequences, or the albumin-bioconjugation mechanism itself may find the With DAC variant more relevant to their experimental design.
-
Comparative studies examining both variants side by side are themselves a recognised area of GHRH analogue research, since the structural difference between them provides a controlled way to isolate the pharmacokinetic variable from the receptor-pharmacology variable.
This is a description of which research questions each compound’s documented properties are suited to investigating — it is not a recommendation about how frequently, or in what manner, either compound should be administered.
Research-Grade Verification Standards for CJC-1295
Because the two variants differ by a single, chemically specific modification (the DAC maleimide-lysine extension), analytical verification is what actually confirms which compound a batch contains — appearance and labelling alone cannot. The complete framework is set out on the batch verification page.
|
Documentation Standard |
Industry Norm |
Ascend Peptides UK |
|---|---|---|
|
HPLC purity verification |
Self-reported by the supplier |
Independent HPLC by Janoshik, ≥98% verified for both variants |
|
LC-MS molecular identity |
Often not performed, or not variant-specific |
LC-MS confirmation on every batch, distinguishing the DAC-conjugated mass from the unconjugated backbone mass |
|
Batch-specific Certificate of Analysis |
Generic or unavailable |
Per batch CoA tied to vial lot number for both variants |
|
Reconstitution guidance specificity |
Frequently generic across all peptides |
Acetic Acid Water requirement documented specifically for both CJC-1295 variants |
For the complete research grade standards framework, see the research grade standards page. Full laboratory quality control methodology is documented on the how we test peptides page.
Evidence Base and Research Limitations
Researchers designing experiments comparing these two variants should be aware of some specific limits to the current evidence base:
-
The human pharmacokinetic data for CJC-1295 With DAC (the approximate 5.8–8.1 day half-life estimate and the GH/IGF-1 elevation figures) come from a single published clinical pharmacology study (Teichman et al., 2006) in a defined cohort of healthy adults, not a large or repeatedly replicated body of human PK data. No directly comparable published human or nonclinical pharmacokinetic study of CJC-1295 Without DAC (the free-base, non-DAC active moiety) has been identified for this page. The FDA’s 2024 evaluation of CJC-1295 nominations for the compounding bulk drug substances list states plainly that direct evidence comparing the half-life of the two forms is lacking, and that FDA has not identified nonclinical pharmacokinetic/toxicokinetic studies of CJC-1295 (free base), CJC-1295 acetate, CJC-1295 DAC (free base), or CJC-1295 DAC acetate.
-
The albumin-bioconjugation mechanism itself was characterised primarily through preclinical (rodent) receptor-activation and structural work (Jette et al., 2005); human confirmation of the precise binding mechanism relies on the pharmacokinetic consequences observed in Teichman et al. rather than direct human structural data.
-
The persistence-of-pulsatility finding (Ionescu & Frohman, 2006) is a specific, single-study finding under a defined continuous-stimulation protocol; it should not be over-generalised to every possible dosing pattern or experimental timeframe.
-
The four base amino acid substitutions distinguishing Modified GRF(1-29) from native GHRH(1-29) are documented in the structural literature (Campbell et al., 1991), but this page does not assert the exact position of every substitution beyond those confirmed in the available published sequence data.
These limitations are a normal feature of a well-studied but not exhaustively characterised research compound family, and are noted here so researchers can factor them into experimental design.
CJC-1295 Research Resources at Ascend Peptides UK
This page compares CJC-1295 With DAC and Without DAC directly — their structure, mechanism and research-relevant differences. For product specification, pricing and detailed laboratory application guidance on each individual compound, see the dedicated resources below.
-
CJC-1295 With DAC 10mg — the standalone product listing.
-
CJC-1295 Without DAC 10mg — the standalone product listing.
-
CJC-1295 Without DAC research guide — practical laboratory application and reconstitution reference.
Both variants are part of the wider GH axis research peptides UK range, itself part of the complete research peptides UK catalogue.
CJC-1295 With DAC vs Without DAC: Frequently Asked Questions
What is the actual difference between CJC-1295 With DAC and Without DAC?
Both share the same tetrasubstituted, 29-amino-acid GRF(1-29) structural backbone. CJC-1295 With DAC carries an additional C-terminal Drug Affinity Complex (DAC) extension — a maleimidopropionyl-lysine group that covalently binds circulating serum albumin. CJC-1295 Without DAC lacks this extension and remains a free, unconjugated peptide. That single structural difference is responsible for the large difference in reported half-life between the two.
Is CJC-1295 Without DAC the same thing as Mod GRF 1-29?
In current commercial and research-chemical usage, yes — the two names are used interchangeably for the same 29-amino-acid non-DAC backbone. This is a naming convention rather than confirmation that commercially available material is identical to a specific studied substance: the original human trials discussed on this page (Teichman et al., 2006; Ionescu & Frohman, 2006) studied the DAC-conjugated molecule only, and the FDA’s 2024 evaluation of CJC-1295 nominations treats “CJC-1295 (free base)” and “CJC-1295 (DAC) (free base)” as two distinct active moieties rather than interchangeable forms of one studied compound.
Does the DAC modification change which receptor CJC-1295 binds?
No. Both variants are selective agonists at the same target, the GHRH receptor (GHRHR), and both trigger the same downstream cAMP/PKA signalling cascade. The DAC modification changes systemic persistence via albumin binding, not receptor selectivity or downstream signalling identity.
Does CJC-1295 With DAC produce continuous, non-pulsatile GH release?
Not according to the available published data. Ionescu & Frohman (2006) found that pulsatile GH secretion persists even during prolonged, continuous CJC-1295 With DAC stimulation — sustained systemic exposure to the compound does not equate to a flat, continuous GH release pattern at the level of pituitary output. No comparable study has been identified measuring the GH secretion pattern produced by CJC-1295 Without DAC specifically, so this page does not assert a corresponding pattern for that variant.
What is the reported half-life of each variant?
Published human data exists only for CJC-1295 With DAC: Teichman et al. (2006) estimated a terminal half-life of approximately 5.8–8.1 days. No directly comparable published human pharmacokinetic study has been identified for CJC-1295 Without DAC (the 29-amino-acid non-DAC active moiety). The FDA’s 2024 evaluation of CJC-1295 nominations similarly states that direct evidence comparing the two forms’ half-lives is lacking, and that no nonclinical pharmacokinetic/toxicokinetic studies of the free-base form have been identified. The commonly repeated “~30 minute” figure for CJC-1295 Without DAC should be treated as an unsourced estimate rather than data of equivalent quality to the DAC human trial data.
How does CJC-1295 relate to Tesamorelin and Ipamorelin?
Tesamorelin is a full-length, 44-amino-acid GHRH analogue rather than a truncated GRF(1-29)-based analogue like either CJC-1295 variant. Ipamorelin targets a different receptor entirely (GHS-R1a, not GHRHR). All three are studied within the same broader GH axis research category but represent mechanistically and structurally distinct research tools — see the GH axis research peptides UK hub for the complete category framework.
What is the WADA and MHRA status of CJC-1295?
Both CJC-1295 With DAC and Without DAC are listed on the World Anti-Doping Agency (WADA) Prohibited List under category S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics), prohibited at all times for athletes subject to WADA jurisdiction. Neither variant is licensed by the MHRA as a medicinal product under the UK Human Medicines Regulations 2012. Ascend Peptides UK supplies both strictly for in-vitro and preclinical laboratory research.
Scientific References
Jette, L., Leger, R., Thibaudeau, K., Ferland, N., Devost, D., Levesque, C., … et al. (2005). “Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-lasting analog of GRF.” Endocrinology, 146(7), 3052–3058. — original structural characterisation of the DAC albumin-bioconjugation mechanism.
Teichman, S.L., Neale, A., Lawrence, B., Gagnon, C., Castaigne, J.P., & Frohman, L.A. (2006). “Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults.” The Journal of Clinical Endocrinology & Metabolism, 91(3), 799–805. — human pharmacokinetic and pharmacodynamic characterisation, source of the half-life and GH/IGF-1 elevation figures referenced above.
Ionescu, M., & Frohman, L.A. (2006). “Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog.” The Journal of Clinical Endocrinology & Metabolism, 91(12), 4792–4797. — source of the pulsatility-persistence finding referenced above.
Campbell, R.M., Lee, Y., Rivier, J., Heimer, E.P., Felix, A.M., & Koerber, S.C. (1991). “Enhanced stability and potency of novel growth hormone-releasing factor (GRF) analogues derived from rodent and human sequences.” Peptides. — original structural work on stabilised GRF(1-29) analogues underlying the Modified GRF(1-29) backbone.
U.S. Food and Drug Administration. (2024, December 4). FDA Briefing Document: Pharmacy Compounding Advisory Committee (PCAC) Meeting. — source of the FDA statements referenced above on the lack of direct comparative pharmacokinetic evidence between CJC-1295 DAC and CJC-1295 without DAC, the absence of identified nonclinical PK/TK studies of the free-base (non-DAC) form, and the treatment of free-base, acetate, and DAC forms as distinct bulk drug substances.
RESEARCH USE ONLY
All products supplied by Ascend Peptides UK are intended strictly for in-vitro and preclinical laboratory research purposes only. Neither CJC-1295 With DAC nor CJC-1295 Without DAC is a licensed medicinal product under the UK Human Medicines Regulations 2012, and neither is for human or veterinary use. No dosing or administration guidelines are provided. Purchasers must be 18 years of age or older and must confirm that products are being purchased solely for lawful laboratory research purposes. Ascend Peptides UK reserves the right to request additional information regarding intended research use and to decline orders where appropriate.
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