CJC-1295 with DAC stays bound to albumin, a blood protein that circulates for about three weeks. That tether is the entire reason one weekly injection keeps IGF-1 elevated for days.
CJC-1295 is sold in two forms that share a name and almost nothing else. The difference is the drug affinity complex, or DAC. With DAC, the peptide binds albumin and stays active for days [1]. Without DAC, the same GHRH backbone (correctly called mod-GRF(1-29)) clears in minutes. That single design choice changes the half-life, the dosing schedule, and how the whole protocol is built.
- DAC is an albumin-binding linker that extends CJC-1295's half-life from minutes to days [1]
- With DAC: half-life 6 to 8 days, dosed weekly, IGF-1 stays elevated [2]
- Without DAC (mod-GRF 1-29): half-life ~30 minutes, dosed 1 to 3x daily with ipamorelin
- Pulsatile GH release persists even with continuous DAC stimulation [3]
- Neither form is FDA-approved; both are compounded [6]
What the DAC Actually Is
DAC is a small chemical group, a maleimidopropionic acid linker, attached to the peptide so it binds covalently to albumin, the most abundant protein in blood [1]. Albumin circulates for roughly three weeks, so a peptide tethered to it is shielded from the enzymes that would otherwise clear it in minutes. Jetté and colleagues identified this albumin-binding conjugate of hGRF(1-29) as CJC-1295, a GRF analog that keeps working for days [1].
The no-DAC version keeps the stabilizing amino acid substitutions of the backbone but drops the albumin linker. Those backbone changes, including the D-Ala substitution that resists enzymatic breakdown, extend the half-life modestly compared to native GHRH [4]. Modestly means minutes to tens of minutes, not days.
The Half-Life Difference
CJC-1295 with DAC produces GH and IGF-1 elevation that lasts several days after one injection. In healthy adults, single doses raised mean IGF-1 for up to about six days, and weekly dosing held it elevated [2]. Mod-GRF(1-29) has a half-life around 30 minutes and is gone from circulation within hours.
| CJC-1295 with DAC | CJC-1295 without DAC (mod-GRF 1-29) | |
|---|---|---|
| Albumin binding | Yes | No |
| Half-life | 6 to 8 days | ~30 minutes |
| Dosing frequency | Once or twice weekly | 1 to 3 times daily |
| GH release pattern | Sustained elevation, pulses preserved [3] | Sharp, short pulse per dose |
| Usual pairing | Sometimes run alone | Paired with ipamorelin |
Sustained Elevation vs the Natural Pulse
The design debate is whether steady stimulation or a sharp pulse better matches normal physiology. Natural GH release is pulsatile, with peaks at night and low troughs between. A concern with DAC was that constant stimulation might flatten that pattern into a steady bleed. Ionescu and Frohman found that pulsatile GH secretion persists during continuous stimulation by CJC-1295, with the drug raising GH mainly by increasing pulse amplitude and trough levels rather than erasing the pulses [3].
The short-acting version reproduces a sharper on-and-off pulse by design. Dosed before bed with ipamorelin, mod-GRF(1-29) creates a brief, large GH release and then clears, which some clinicians prefer for staying closer to the natural rhythm [5].
How the Difference Changes Dosing
- With DAC: one or two injections per week. Convenience is the main draw. IGF-1 stays elevated continuously, so response is tracked with a single IGF-1 draw rather than timed to a dose [2].
- Without DAC: one to three injections per day, usually at bedtime and sometimes after training, almost always stacked with ipamorelin to add the second pathway [5].
- Timing matters more for the no-DAC version. It is dosed on an empty stomach, since food and the insulin response to it blunt the GH pulse.
DAC buys convenience: one weekly shot and steady IGF-1. No-DAC buys control: a pulsed pattern closer to natural physiology and dose changes that reverse within hours instead of days.
Which Form Is Used When
The no-DAC version paired with ipamorelin is the more common telehealth protocol, because the pulsed pattern is closer to normal physiology and dose adjustments are easier to reverse. The DAC version is chosen mainly when injection frequency is the deciding factor. Neither is FDA-approved. For the broader mechanism and evidence, see the full CJC-1295 guide.
With-DAC or without, the response is only meaningful against a baseline. SystemLabs runs an IGF-1 before prescribing and retests to confirm the dose is working, whichever CJC-1295 form fits your protocol.
How IGF-1 Monitoring Differs Between the Two
The half-life difference changes how you read a lab. With DAC, IGF-1 sits at a steady elevated level, so a single draw at any point reflects the protocol [2]. There is no need to time the blood test to a dose because the stimulation is continuous.
With the no-DAC version, IGF-1 still integrates the effect of repeated daily pulses over days, so a baseline and a roughly 90-day retest remain the standard checkpoints. In both cases the point of the retest is the same: confirm IGF-1 moved into the target range without overshooting it. A protocol run without any IGF-1 draw gives neither the patient nor the prescriber a way to know which of those two happened.
Common Mistakes With Each Form
- Treating the two forms as interchangeable on dose; a weekly DAC dose and a daily no-DAC dose are not the same amount of drug over time
- Dosing mod-GRF(1-29) after a meal, which blunts the GH pulse; it belongs on an empty stomach
- Assuming DAC erases the natural GH rhythm; pulsatility is preserved even under continuous stimulation [3]
- Running either form without a baseline IGF-1, which removes the only objective measure of response
Regulatory Status
Neither form of CJC-1295 is FDA-approved. Both are compounded, and CJC-1295 appears on FDA's list of bulk substances that may present significant safety risks for compounding [6]. As a growth hormone releasing factor, it is prohibited in competition by the World Anti-Doping Agency [7].
Bottom Line
Frequently Asked Questions
What is the difference between CJC-1295 with and without DAC?
The drug affinity complex (DAC) is an albumin-binding linker. With DAC, CJC-1295 binds albumin and has a half-life of about 6 to 8 days, so it is dosed weekly [1][2]. Without DAC, the peptide (correctly called mod-GRF(1-29)) has a half-life around 30 minutes and is dosed one to three times daily, usually with ipamorelin. Same GHRH backbone, very different pharmacokinetics.
How often do you inject CJC-1295 with DAC?
Once or twice weekly. Because the DAC linker tethers the peptide to albumin, which circulates for about three weeks, a single dose keeps IGF-1 elevated for days [2]. This is the main practical advantage over the no-DAC version, which requires daily injections.
Is CJC-1295 without DAC the same as mod-GRF(1-29)?
Yes. CJC-1295 without DAC and mod-GRF(1-29) are the same molecule: a modified GHRH(1-29) fragment with stabilizing amino acid substitutions but no albumin-binding linker [1][4]. Mod-GRF(1-29) is the technically accurate name. It clears in minutes to hours and is dosed like sermorelin.
Does CJC-1295 with DAC stop the natural GH pulse?
No. Despite the concern that constant stimulation would flatten GH into a steady bleed, Ionescu and Frohman found that pulsatile GH secretion persists during continuous stimulation by CJC-1295 [3]. The drug raises GH mainly by increasing pulse amplitude and trough levels rather than eliminating the pulses.
Which is better, CJC-1295 with or without DAC?
Neither is universally better; they solve different problems. The no-DAC version paired with ipamorelin is more common in telehealth because the pulsed pattern is closer to natural physiology and dose changes reverse quickly. The DAC version wins on convenience, with one weekly injection and steady IGF-1 [2]. Neither is FDA-approved [6].
References
- 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 GRF analog Endocrinology, 2005. PMID: 15817669. https://pubmed.ncbi.nlm.nih.gov/15817669/
- 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 Journal of Clinical Endocrinology & Metabolism, 2006. PMID: 16352683. https://pubmed.ncbi.nlm.nih.gov/16352683/
- Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog Journal of Clinical Endocrinology & Metabolism, 2006. PMID: 17018654. https://pubmed.ncbi.nlm.nih.gov/17018654/
- Incorporation of D-Ala2 in growth hormone-releasing hormone-(1-29)-NH2 increases the half-life and decreases metabolic clearance in normal men Journal of Clinical Endocrinology & Metabolism, 1994. PMID: 7962295. https://pubmed.ncbi.nlm.nih.gov/7962295/
- Ipamorelin, the first selective growth hormone secretagogue European Journal of Endocrinology, 1998. PMID: 9849822. https://pubmed.ncbi.nlm.nih.gov/9849822/
- Certain bulk drug substances for use in compounding that may present significant safety risks FDA.gov, Human Drug Compounding, 2026. FDA Category 2 bulk substances list. https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
- The 2026 Prohibited List: International Standard, section S2.2.4 growth hormone releasing factors World Anti-Doping Agency, 2026. WADA 2026 Prohibited List. https://www.wada-ama.org/en/resources/2026-prohibited-list
