CJC-1295 No-DAC vs DAC: Half-Life, GH Pulse & the Difference

CJC-1295 No-DAC vs DAC at a Glance

CJC-1295 is a synthetic analog of the bioactive 1-29 fragment of growth-hormone-releasing hormone (GHRH / GRF). Both the "No-DAC" and "with-DAC" forms carry the same modified GRF(1-29) backbone — four amino-acid substitutions (position 2 L-Ala→D-Ala, position 8 Asn→Gln, position 15 Gly→Ala, position 27 Met→Leu) that confer resistance to DPP-IV cleavage. The single structural fork is the Drug Affinity Complex (DAC), an added C-terminal group that binds serum albumin. That one feature is the whole comparison: it is the reason the two forms behave nothing alike in the body.

A naming caveat worth getting straight up front: in the strict pharmacology literature, "CJC-1295" denotes the DAC version, while "CJC-1295 without DAC" is a vendor/community term for the bare modified GRF(1-29) peptide. So the published "CJC-1295" half-life and GH/IGF-1 numbers describe the DAC compound — a point to keep clear throughout.

The sections below profile each form on its own, then return to the differences in detail. Both are Research Use Only (RUO) laboratory materials — not approved drugs and not for human use.

CJC-1295 No-DAC (Modified GRF 1-29)

CJC-1295 without DAC — also called modified GRF 1-29 or "mod-GRF 1-29" — is the bare GRF(1-29) sequence carrying the four DPP-IV-resistant substitutions and nothing else. There is no albumin-binding moiety. Its only stabilization comes from those substitutions, which raise the half-life from the ~5–10 minutes of native GRF(1-29) to a commonly cited ~30 minutes.

Because it lacks any long-acting anchor, the No-DAC peptide is cleared within hours and produces a single, brief, pulsatile GH release per dose — one sharp pulse that returns toward baseline, mimicking the body's native episodic GH rhythm. It is the form supplied on this site, blended with Ipamorelin in the CJC5 product.

CJC-1295 With DAC (DAC:GRF)

The DAC form — the compound that the original ConjuChem/Jette literature actually calls "CJC-1295" — takes the same modified GRF(1-29) and adds a Drug Affinity Complex at the C-terminus: a maleimidopropionamide-lysine group. The maleimide is thiol-selective. After subcutaneous injection it reacts with the single free cysteine residue (Cys-34) on circulating serum albumin to form a covalent, stable thioether bond.

Albumin is a long-lived circulating carrier that is too large for renal glomerular filtration and shields the bound peptide from peptidase degradation. That is the physical reason the DAC form's half-life jumps to multiple days. Jette et al. (2005, Endocrinology) demonstrated that the hGRF(1-29)-albumin bioconjugate still activates the GRF receptor on the rat anterior pituitary in vivo — the originating mechanistic paper for the albumin-binding technology.

In healthy adults, two randomized, placebo-controlled, double-blind ascending-dose trials established the DAC form's pharmacokinetics. Teichman et al. (2006, Journal of Clinical Endocrinology & Metabolism) reported an estimated half-life of 5.8–8.1 days; a single subcutaneous dose raised GH 2- to 10-fold for 6+ days and IGF-1 1.5- to 3-fold for 9–11 days, with no serious adverse reactions reported. Preclinically, once-daily CJC-1295 normalized growth in the GHRH-knockout mouse (Alba et al., 2006), confirming restoration of the GH/IGF-1 axis when endogenous GHRH is absent.

Key Differences

Strip away the shared backbone and the comparison reduces to a few clean contrasts:

Mechanism: One Added Group

Both forms are GHRH-receptor agonists at the anterior pituitary somatotrophs, driving endogenous GH synthesis and release; downstream, GH raises hepatic IGF-1. The mechanistic fork is the DAC alone. The C-terminal maleimide that covalently binds albumin Cys-34 is the sole reason for the multi-day half-life — the No-DAC form has no such anchor.

Half-Life: Minutes vs Days

No-DAC sits at a commonly cited ~30 minutes (structurally rationalized). DAC is measured at 5.8–8.1 days in human data (Teichman et al., 2006). The albumin-bound complex resists renal filtration and enzymatic degradation, which is the physical basis for that multi-day window.

Signaling: Pulse vs Bleed

The No-DAC form contributes a discrete pulse — one sharp GH release returning toward baseline within hours. The DAC form produces a sustained elevation, a continuous "bleed" that raises trough/basal GH and keeps IGF-1 chronically elevated for days to weeks. A key nuance: even under continuous DAC stimulation, native pulsatile GH secretion persists. Ionescu & Frohman (2006, JCEM) showed by deconvolution of 24-hour GH profiles that pulse frequency and amplitude were unchanged while trough GH rose roughly 7.5-fold — so the DAC form elevates basal GH on top of, not in place of, native pulses.

A Difference in Kinetics, Not Receptor

Pulsatile (No-DAC) signaling is often argued to better preserve receptor sensitivity and the somatostatin/IGF-1 negative-feedback rhythm, whereas continuous (DAC) signaling holds IGF-1 persistently high. It is worth being precise here: this is a difference in kinetics, not in the receptor engaged — both forms hit the same GHRH receptor. The "more physiological" framing for pulsatile signaling is mechanistically reasonable (native GH is pulsatile, and Ionescu 2006 confirms pulses persist), but it has not been settled by a head-to-head outcome trial and should not be stated as a proven benefit.

How They're Studied & Paired

The two forms imply different research cadences. The No-DAC peptide's short window means protocols typically administer it frequently to recreate multiple pulses, while the DAC form's multi-day half-life means a single dose sustains exposure for many days.

The No-DAC + Ipamorelin Pairing

The No-DAC form is commonly combined with Ipamorelin, and that is the on-site CJC5 blend. Ipamorelin works through a different receptor — the growth hormone secretagogue receptor 1a (GHS-R1a / ghrelin receptor) — so the blend recruits two complementary GH-release pathways (a GHRH input plus a ghrelin-mimetic input) for a synergistic pulse. Raun et al. (1998, European Journal of Endocrinology) characterized Ipamorelin as the first selective growth hormone secretagogue: even at doses ~200-fold above its GH-release threshold, it did not significantly elevate ACTH or cortisol above GHRH-stimulation levels. That selectivity is the rationale for pairing it with the GRF peptide.

Reconstitution & Handling for Research

Both forms ship as lyophilized (freeze-dried) powder. General lab-handling practice for GHRH-analog and secretagogue peptides: store the lyophilized powder cold and protected from light and moisture; reconstitute with bacteriostatic or sterile water; once in solution, keep refrigerated and use within a limited window, since peptides in solution are less stable than the dry powder. Avoid repeated freeze-thaw cycles and vigorous agitation (peptides can shear or aggregate), and let vials reach the appropriate temperature before opening to limit condensation. Specific storage temperatures, reconstitution volumes, and stability windows should follow the supplier's Certificate of Analysis (COA) and product documentation.

Frequently Asked Research Questions

What is the difference between CJC-1295 No-DAC and DAC?

Both share the same modified GRF(1-29) core peptide. The only structural difference is the DAC (Drug Affinity Complex) — a C-terminal maleimide group on the DAC version that binds serum albumin. That one feature extends the half-life from a commonly cited ~30 minutes (No-DAC) to ~6–8 days (DAC) and converts a discrete GH pulse into a sustained multi-day elevation.

What is the half-life of CJC-1295?

It depends entirely on which form. The published human half-life for CJC-1295 with DAC is 5.8–8.1 days (Teichman et al., 2006, JCEM). The No-DAC form's commonly cited half-life is ~30 minutes — a structurally rationalized figure, not a large-trial endpoint. Do not conflate the two: the published "CJC-1295" half-life describes the DAC compound.

How does the DAC actually work?

The DAC is a thiol-selective maleimide group. After injection it reacts with the single free cysteine residue (Cys-34) on serum albumin to form a covalent thioether bond. The resulting albumin-bound complex is too large for renal filtration and is shielded from peptidase degradation, which is the physical reason for the multi-day half-life. Jette et al. (2005) showed the albumin bioconjugate still activates the GRF receptor.

Why is the No-DAC form paired with Ipamorelin?

Ipamorelin acts on a different receptor (the ghrelin / GHS-R1a receptor) than the GRF peptide (the GHRH receptor), so the blend recruits two complementary GH-release pathways. Ipamorelin is also a selective secretagogue that raises GH without significantly elevating cortisol or ACTH (Raun et al., 1998). The combination is mechanistically rational, though the blend itself lacks dedicated combination-trial data.

Which form does Elytra Labs supply?

The on-site product (CJC5) is the No-DAC + Ipamorelin blend. The DAC version is presented for information only and is not sold on this site. Both forms are Research Use Only laboratory materials — not approved drugs and not for human use.