April 16, 2026·6 min read·growth-hormone, ghrh, comparison
CJC-1295—with DAC or without?
Half-life, pulsatile vs continuous GH release, and why we carry both versions.
Half-life, pulsatile vs continuous GH release, and why we carry both versions.
The single most-confusing decision in growth-hormone research is a two-word question: "DAC or no-DAC?" CJC-1295 exists in two forms with radically different pharmacokinetics, and the choice between them reshapes your entire protocol—injection frequency, dosing schedule, and the nature of GH release itself. Understanding what DAC does (and doesn't do) clarifies the decision.
CJC-1295 is a 30-amino-acid peptide—specifically, a tetra-substituted analogue of GHRH(1-29). The modifications at four positions reduce its susceptibility to DPP-4 cleavage, the enzyme that rapidly destroys native GHRH in circulation. Without those substitutions, native GHRH survives maybe three minutes in the bloodstream. CJC-1295 survives roughly 30 minutes—a ten-fold improvement, but still short-lived.
This 30-minute half-life is the baseline for "CJC-1295 without DAC," sometimes called "Mod GRF 1-29" in older literature. It's the version designed for pulsatile research: dosed two to three times daily, it generates discrete GH-release pulses spaced a few hours apart.
DAC stands for Drug Affinity Complex—specifically, a maleimido-propionic acid linker that covalently binds to serum albumin's free cysteine residue (Cys34). CJC-1295 with DAC is identical to the base molecule, except it carries this albumin-binding tag. Once injected, the peptide attaches to albumin and travels with it. Albumin's circulating half-life is ~19 days, so the peptide is now shielded from rapid clearance. The effective half-life stretches from ~30 minutes to approximately 8 days.
The pharmacological consequence is a shift from pulsatile to continuous. With no-DAC, you're stimulating the GHRH receptor multiple times daily in discrete windows, each triggering a GH pulse. With DAC, you're applying steady stimulus for a week at a time, producing a continuous background GH elevation plus attenuated pulses.
The mechanistic argument for pulsatile dosing is compelling. Growth hormone doesn't work well on a static schedule. The pituitary evolved to release GH in discrete pulses (roughly every 90 minutes during the day, more frequently at night). The downstream machinery—GH receptors, JAK-STAT signaling, gene transcription in skeletal tissue—responds robustly to this pulsatile pattern. Chronic elevation, by contrast, triggers receptor downregulation and blunted responses.
Studies comparing pulsatile GH injection to continuous infusion show that pulsatile release drives better lean-mass gains and more robust metabolic remodeling, even when the total 24-hour exposure is matched. The rhythm matters. CJC-1295 without DAC preserves this rhythm.
The practical argument for DAC is equally real. Once-weekly injection versus twice or three times daily is a massive compliance advantage. A researcher who can't sustain daily injections, or who finds the ritual burdensome, will not complete a protocol. A protocol not completed produces no data. From this angle, the theoretical superiority of pulsatile is moot if the researcher abandons it after two weeks.
There's a third consideration: tolerance. With continuous stimulation (DAC), the pituitary can begin to desensitize to the peptide—the response fades over time. This is less of a problem with pulsatile dosing, where intermittent stimulus keeps the receptor from adapting. For research cycles longer than 12 weeks, the no-DAC version may maintain more consistent GH output.
Conversely, some researchers intentionally dose in cycles (8–12 weeks on, 4 weeks off) to reset the pituitary's sensitivity. Within that framework, DAC's convenience during the on-phase is the larger practical win.
These two versions don't stack identically. CJC-1295 without DAC is nearly always paired with a GHRP (Ipamorelin, GHRP-2, GHRP-6) to achieve the synergistic GH pulses mentioned in the secretagogue category guide. The two peptides hit different receptors and produce a bigger pulse together than either alone.
CJC-1295 with DAC is sometimes run solo, relying on its continuous background stimulation, though some researchers stack it with a GHRP for additional acute pulses on top of the baseline bleed. The rationale is less clear-cut—you're layering a pulsatile stimulus onto a continuous one, which creates a hybrid pattern that's less well-characterized in the literature.
We stock CJC-1295 without DAC and CJC-1295 with DAC because the choice depends entirely on the researcher's priority and constraints. Neither is objectively superior; the right choice depends on whether your endpoint favors pulsatile rhythm or maximal convenience, and how you plan to stack it.
If you're committed to the daily-injection discipline and want the theoretical GH-kinetics advantage, no-DAC plus a GHRP is the evidence-preferred stack. If compliance is the bottleneck and once-weekly injection is the realistic target, DAC is the move—still a secretagogue with intact feedback, just with a flattened profile.
Both versions are typically run for 8–16 week cycles. Titration is less critical than with GLP-1 agonists; side-effect burden is mild. Combine no-DAC with GHRP at a 1:1 molar ratio or adjust based on GH-response markers if you have them (IGF-1, HGH levels mid-protocol).
For DAC, typical dosing is 2 mg once weekly, though some protocols run 2 mg twice weekly. Observe for changes in injection-site reactions, mood, or water retention over the first month and adjust if needed.
| Property | Without DAC | With DAC |
|---|---|---|
| Half-life | ~30 minutes | ~8 days |
| Dosing frequency | 2-3x daily | Once weekly |
| GH release pattern | Pulsatile (discrete) | Continuous (bleed) |
| Best for | Pulsatile rhythm targeting | Convenience + compliance |
| Desensitization risk | Lower (intermittent stimulus) | Higher (continuous stimulus) |
| Common stacking | + Ipamorelin or GHRP | Can run solo |
CJC-1295 without DAC is CJC-1295; with DAC is CJC-1295 (DAC). Ipamorelin, GHRP-2, and GHRP-6 are the most-common pairings with no-DAC. See the growth-hormone secretagogues guide for the full category context.
Should you choose DAC or no-DAC CJC-1295? No-DAC if you can sustain 2-3 daily injections and want pulsatile GH rhythm. With-DAC if once-weekly convenience is the bottleneck to compliance. Neither is objectively superior; the right choice depends on your endpoint (rhythm vs simplicity) and discipline.
What does DAC actually do on CJC-1295? DAC (Drug Affinity Complex) attaches the peptide to serum albumin, extending half-life from ~30 min to ~8 days. This converts pulsatile dosing into continuous bleed, reducing injection frequency but flattening the natural GH rhythm.
Which version should you stack with Ipamorelin? CJC-1295 without DAC. It's the classic pulsatile stack—two peptides hitting different receptors produce synergistic GH pulses. With-DAC creates a hybrid pattern (continuous baseline + acute pulses) that's less well-characterized.
Can CJC-1295 with DAC cause tolerance? Yes. Continuous GHRH receptor stimulation can trigger desensitization over 12+ weeks. Cycling protocols (8-12 weeks on, 4 weeks off) help reset sensitivity. Without-DAC's intermittent dosing has lower desensitization risk.
