Comparing CJC-1295 and CJC-1295 with DAC: Pharmacokinetics, Growth Hormone Release and Research

CJC-1295 with DAC and CJC-1295 without DAC (Mod GRF 1-29) are both synthetic GHRH analogs that stimulate pituitary growth hormone release, but they differ in one critical way: the Drug Affinity Complex extends the half-life from approximately 30 minutes to 6–8 days, fundamentally changing the GH release pattern from pulsatile bursts to sustained elevation.

The naming confusion between these two compounds is the single most common source of buyer error in the growth hormone secretagogue market. Both share the same 29-amino-acid core with 4 amino acid substitutions (D-Ala², Gln⁸, Ala¹⁵, Leu²⁷), but the DAC version adds a maleimidopropionyl-lysine residue at position 30 that covalently binds serum albumin in the bloodstream — an addition that transforms the compound's pharmacokinetics, dosing schedule, and GH release pattern. Critically, only CJC-1295 with DAC has published human clinical data. The version most commonly purchased and stacked with ipamorelin — the no-DAC version — has zero dedicated human trials. Both versions are FDA Category 2 compounds, banned from licensed compounding pharmacies as of 2023. Peptigrity's independent lab tests and community reviews can help verify which version a vendor actually supplies.

What Is CJC-1295? Understanding the Base Peptide Before the DAC Question

CJC-1295 is a synthetic analog of the first 29 amino acids of human growth hormone-releasing hormone (GHRH), modified at 4 positions to resist enzymatic degradation — the same base peptide exists in both the "with DAC" and "without DAC" versions, but the Drug Affinity Complex addition transforms it from a short-acting pulse trigger into a week-long sustained-release compound.

Native GHRH is a 44-amino-acid hypothalamic peptide that signals the anterior pituitary to release growth hormone. Its therapeutic utility is severely limited by a half-life of approximately 7 minutes — the enzyme dipeptidyl peptidase IV (DPP-IV) cleaves it almost immediately after release into the bloodstream.

Sermorelin (GRF 1-29) was the first truncated GHRH analog — a 29-amino-acid version that retained full receptor-binding activity. It received FDA approval in 1997 for growth hormone deficiency in children (withdrawn in 2008 for commercial reasons, not safety), but its half-life of approximately 10–20 minutes still required frequent injections.

CJC-1295 without DAC (Modified GRF 1-29) improved on sermorelin with 4 specific amino acid substitutions:

• Position 2: D-Alanine replaces L-Alanine — prevents DPP-IV cleavage, the primary degradation pathway

• Position 8: Glutamine replaces Asparagine — prevents asparagine rearrangement and amide hydrolysis

• Position 15: Alanine replaces Glycine — enhances receptor binding affinity

• Position 27: Leucine replaces Methionine — prevents methionine oxidation during manufacturing and storage

These substitutions extend the half-life to approximately 30 minutes and significantly improve stability, but the peptide still requires multiple daily injections to maintain elevated GH levels.

CJC-1295 with DAC takes the same tetrasubstituted peptide and adds a 30th residue — lysine — with a maleimidopropionyl (MPA) group that forms a covalent bond with Cys34 on serum albumin after subcutaneous injection. This albumin bioconjugation was developed by ConjuChem Biotechnologies (Montreal) and extends the half-life to 5.8–8.1 days in humans, as confirmed in the landmark study "Prolonged Stimulation of Growth Hormone (GH) and Insulin-Like Growth Factor I Secretion by CJC-1295" (Teichman et al., Journal of Clinical Endocrinology & Metabolism, 2006). It is important to note that the name "CJC-1295" technically refers to the DAC version — the compound ConjuChem developed and tested clinically. The no-DAC version should properly be called "Modified GRF (1-29)" or "Mod GRF 1-29," though vendors frequently and inaccurately label it as "CJC-1295 without DAC." As Wikipedia specifically notes, "CJC-1295 and Modified GRF (1-29) is equated falsely in several scientific papers."

How Do the Two Versions Differ? 4 Key Comparisons

The 4 differences that matter between CJC-1295 with and without DAC are half-life, GH release pattern, dosing frequency, and stacking compatibility — and all 4 stem from the same molecular change: the albumin-binding Drug Affinity Complex.

Difference 1: Half-Life (~30 Minutes vs 6–8 Days)

CJC-1295 without DAC clears the body within approximately 30 minutes to 2 hours. It produces a short, sharp GH pulse and is then metabolised — pharmacologically similar to the body's own GHRH, but lasting about 4 times longer. CJC-1295 with DAC remains active for 5.8–8.1 days after a single injection (Teichman et al. 2006), because the albumin-bound conjugate is protected from enzymatic degradation and renal clearance. This is a ~200-fold difference in duration of action from one molecular addition.

Difference 2: GH Release Pattern (Pulsatile vs Sustained)

Natural growth hormone secretion follows a pulsatile rhythm — approximately 6–12 bursts per day, with the largest pulse occurring during stage 3/4 NREM deep sleep. CJC-1295 without DAC mimics this physiology: each injection triggers a discrete GH pulse that peaks at ~15–30 minutes and subsides, preserving the natural peak-and-trough pattern.

CJC-1295 with DAC produces a different pattern. A study by Ionescu & Frohman (2006, JCEM) assessed GH pulsatility after a single CJC-1295 DAC injection and found that pulsatility was preserved — the pituitary still produced GH in bursts rather than a flat continuous output. However, the trough levels between pulses were markedly elevated, meaning the "valleys" were filled in. The result is best described as pulses riding on top of an elevated baseline, rather than the deep peak-and-trough oscillation the body produces naturally. This nuance is important because most competitor articles claim DAC produces "constant, non-pulsatile" GH elevation — which the Ionescu & Frohman data does not support.

Difference 3: Dosing Frequency (Multiple Daily vs Weekly)

CJC-1295 without DAC is typically administered 2–3 times daily at doses of 100 mcg per injection — commonly pre-bed (to amplify the largest natural GH pulse during sleep) and morning fasted. Some protocols add a third pre-workout injection. CJC-1295 with DAC requires only 1–2 injections per week at doses of 1–2 mg, offering significantly greater convenience but less dosing flexibility.

Difference 4: Stacking Compatibility

CJC-1295 without DAC is the standard pairing partner for growth hormone-releasing peptides (GHRPs) such as ipamorelin, GHRP-2, and GHRP-6. The no-DAC version's short half-life allows precise co-timing with the GHRP injection — both produce a pulse that peaks at ~15–30 minutes, creating a synergistic amplification effect. CJC-1295 with DAC is less commonly stacked with GHRPs because its sustained GHRH activity doesn't synchronise with the pulsatile mechanics of GHRP dosing — the GHRH component is always "on," so the co-timed pulse effect is diluted.

Head-to-Head Comparison:

What Human Research Exists for CJC-1295?

Only CJC-1295 with DAC has published human clinical trial data — two randomised, placebo-controlled studies in healthy adults demonstrated dose-dependent GH increases of 2- to 10-fold for 6+ days and IGF-1 increases of 1.5- to 3-fold for 9–11 days after a single injection — while CJC-1295 without DAC (Mod GRF 1-29) has no dedicated human trials of its own.

CJC-1295 with DAC: 2 Published Human Studies

Study 1 — Teichman et al. 2006 (JCEM)

This was the foundational human study: two randomised, placebo-controlled, double-blind, ascending-dose trials in healthy adults aged 21–61 years. The first trial assessed single doses (28-day observation), while the second assessed 2–3 weekly or biweekly doses (49-day observation). Results showed:

• GH increased 2- to 10-fold for 6+ days after a single injection

• IGF-1 increased 1.5- to 3-fold for 9–11 days after a single injection

• Half-life was 5.8–8.1 days

• After multiple doses, IGF-1 remained elevated above baseline for up to 28 days

• A cumulative effect was confirmed — each successive dose built on the previous elevation

• No serious adverse reactions were reported at doses of 30 or 60 μg/kg

Study 2 — Ionescu & Frohman 2006 (JCEM)

This study specifically assessed whether CJC-1295 DAC preserved the natural pulsatile GH secretion pattern. After a single injection, the researchers found that pulsatility was preserved, but trough GH levels were markedly enhanced — the pulses still occurred, but the baseline between them was elevated. IGF-1 production increased. The authors concluded that "long-acting GHRH preparations may have clinical utility in patients with intact pituitary GH secretory capability."

The Phase II Trial and Its Termination

CJC-1295 with DAC advanced to Phase II clinical trials for lipodystrophy and growth hormone deficiency, developed by ConjuChem Biotechnologies. During the trial, one subject died. The attending physician assessed the most likely cause as asymptomatic coronary artery disease with plaque rupture and occlusion — an event considered unrelated to CJC-1295 treatment. ConjuChem terminated research as a precaution, and no further clinical trials have been initiated for either version of CJC-1295 by any company. This context is important: the single death during the trial has not been attributed to the drug by the investigating physician, but it effectively ended clinical development of the most promising GHRH analog in the pipeline.

CJC-1295 without DAC: The Evidence Gap

CJC-1295 without DAC (Mod GRF 1-29) has no published human clinical trials. Its pharmacology is inferred from two sources: its structural similarity to sermorelin (which does have human data from its FDA approval period), and the shared GHRH receptor mechanism it has with the DAC version. This is the most significant evidence gap in the CJC-1295 comparison — the version most commonly purchased, most commonly stacked with ipamorelin, and most commonly discussed in peptide communities has never been formally studied in humans. All human data cited in support of Mod GRF 1-29 was generated using the DAC version of the molecule.

Understanding the peptide purity standards for these compounds is essential, as the quality of any research-grade peptide directly affects the validity of user-reported experiences that currently serve as the primary evidence base for the no-DAC version.

Pulsatile vs Sustained GH Release — Why Does the Pattern Matter?

Natural growth hormone secretion follows a pulsatile rhythm of 6–12 bursts per day — and whether CJC-1295 should mimic that rhythm (no-DAC) or override it with sustained stimulation (with DAC) is the central pharmacological debate between the two versions.

The pulsatile pattern is not arbitrary. GH pulse amplitude and frequency regulate downstream signalling differently than steady-state GH levels. Pulsatile GH preferentially activates hepatic IGF-1 production, influences body composition partitioning between fat and lean tissue, and maintains receptor sensitivity through intermittent stimulation followed by recovery periods. The largest natural GH pulse occurs during deep sleep (stage 3/4 NREM), which is why most no-DAC protocols target pre-bed injection timing.

The practical argument for CJC-1295 without DAC centres on physiological mimicry: intermittent stimulation preserves the natural peak-and-trough pattern, theoretically reduces the risk of GHRH receptor desensitisation, allows rapid dose adjustment (effects wear off within hours if side effects occur), and maintains the hypothalamic-pituitary feedback loop. The argument for CJC-1295 with DAC centres on the Ionescu & Frohman data: GH pulsatility was preserved even under sustained GHRH stimulation, no evidence of receptor desensitisation was observed within the 49-day study period, and weekly dosing offers substantial convenience.

The honest assessment is that the receptor downregulation concern is theoretical, not proven. The Teichman et al. data showed a cumulative IGF-1 effect over 28–49 days — meaning each successive dose produced progressively higher IGF-1 levels, the opposite of what downregulation would predict. However, no studies have assessed periods beyond 49 days, so the long-term question remains open. The practical consensus among peptide practitioners, including Jay Campbell and Dr. William Seeds (International Peptide Society), favours the no-DAC version for most applications — primarily for physiologic mimicry and stacking flexibility rather than proven safety differences.

Why Is CJC-1295 Without DAC Almost Always Stacked with Ipamorelin?

CJC-1295 without DAC is almost always paired with ipamorelin because they activate two different receptor pathways — GHRH receptor and ghrelin receptor respectively — and the combined pulse produces a GH spike significantly larger than either peptide alone, a synergy that depends on the short-acting timing of the no-DAC version.

The pharmacological logic is straightforward. CJC-1295 (a GHRH analog) binds the GHRH receptor on anterior pituitary somatotropes, amplifying the amplitude of GH pulses by increasing the amount of GH released per pulse. Ipamorelin (a ghrelin mimetic / GHRP) binds the growth hormone secretagogue receptor (GHS-R), which initiates a GH pulse by triggering the somatotrope to fire. The analogy: ipamorelin starts the engine, and CJC-1295 steps on the accelerator. Together, they produce a GH pulse that exceeds what either compound achieves independently — as documented for the GHRH + GHRP mechanism class in Raun et al.'s foundational study on ipamorelin's selective GH release profile.

The no-DAC version is specifically suited to this stacking approach because its short half-life (~30 minutes) means it can be co-timed precisely with the ipamorelin injection. Both peptides produce a GH pulse that peaks at approximately 15–30 minutes and subsides within 1–2 hours, creating a clean synergistic window. The typical protocol — 100 mcg Mod GRF 1-29 + 100–200 mcg ipamorelin, injected together subcutaneously, 2–3 times daily (pre-bed at minimum, plus morning fasted and/or pre-workout) — is based on this pharmacological rationale and practitioner consensus, not published clinical trials of the specific combination.

CJC-1295 with DAC is less suited to stacking because its sustained GHRH activity means the GHRH component is always active. When ipamorelin triggers a GH pulse, the co-stimulation effect is diluted — the pituitary is already under continuous GHRH drive, so the incremental contribution of a pulse-timed GHRP is reduced compared to the no-DAC scenario where the GHRH stimulus arrives precisely when the GHRP pulse fires.

For buyers evaluating pre-mixed CJC-1295/ipamorelin blends, Peptigrity's guide on how to verify peptide quality before you buy covers the 4 additional verification challenges that blended products present.

How to Verify Which Version You Actually Received

Vendor mislabelling of CJC-1295 is one of the most common quality issues in the peptide market — the term "CJC-1295" alone is ambiguous, and without mass spectrometry verification confirming either ~3,367 Da (no DAC) or ~3,647 Da (with DAC), buyers cannot be certain which version they received.

The naming problem is pervasive. Some vendors label Mod GRF 1-29 as "CJC-1295 no DAC" (technically acceptable shorthand), others label it simply as "CJC-1295" (ambiguous — technically this name belongs to the DAC version), and some even apply the DAC label to the wrong compound. Wikipedia explicitly notes that the two compounds "are equated falsely in several scientific papers" — if peer-reviewed journals get the nomenclature wrong, vendor labels are even less reliable.

3 Verification Methods

Mass spectrometry is the definitive test. CJC-1295 without DAC has a molecular weight of approximately 3,367 Da, while CJC-1295 with DAC has a molecular weight of approximately 3,647 Da — a ~280 Da difference that is easily resolvable by standard mass spectrometry for peptides. Any Certificate of Analysis that does not include MS data for a product labelled "CJC-1295" should be treated as incomplete. Peptigrity's guide on red flags in peptide certificates of analysis covers what a reliable CoA should contain.

Dosing format as a practical clue. CJC-1295 without DAC is typically sold in vials of 2–5 mg with instructions for dosing at 100 mcg per injection, 2–3 times daily. CJC-1295 with DAC is typically sold in vials of 2 mg with instructions for dosing at 2 mg per injection, once or twice weekly. A product labelled "CJC-1295" with weekly dosing instructions almost certainly contains the DAC version, while a product labelled "CJC-1295" with multiple-daily dosing instructions is likely Mod GRF 1-29. This is a heuristic, not a verification method — MS confirmation is still necessary.

HPLC purity ≥98% is the baseline quality threshold for either version, confirming that the primary peptide peak represents the intended product rather than degradation fragments or synthesis byproducts. The peptide impurities literature documents systematic quality issues across the unregulated peptide market. Peptigrity's reviewed peptide shops provide vendor-independent quality data and community reviews to help identify reliable sources.

Are Either Version Legal in 2026?

Both CJC-1295 with DAC and CJC-1295 without DAC are classified as FDA Category 2 bulk drug substances — meaning neither can be legally compounded by licensed pharmacies in the US as of 2026 — though sermorelin, the unmodified predecessor, remains legal to compound.

The Category 2 classification was applied in 2023 alongside other growth hormone secretagogues including ipamorelin. The February 2026 HHS announcement regarding the potential reclassification of approximately 14 Category 2 peptides back to Category 1 may affect CJC-1295's status, but final determination has not been formalised as of this writing.

The WADA Prohibited List classifies both versions under S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics), prohibiting their use in and out of competition.

For comparative context: sermorelin (the unmodified GRF 1-29, without the 4 stabilising substitutions or DAC) was FDA-approved from 1997 to 2008 and remains legal to compound under Section 503A in the United States. Tesamorelin (Egrifta) is the only GHRH analog currently FDA-approved for therapeutic use (specifically for HIV-associated lipodystrophy). Both CJC-1295 versions remain widely available as research-use-only (RUO) chemicals from unregulated vendors — legal to possess but not approved for human use.

Peptigrity's guide to peptide legality and regulatory status by country covers the international regulatory landscape in detail.

Frequently Asked Questions

Is Mod GRF 1-29 the same as CJC-1295 without DAC?

Yes — Modified GRF (1-29) and "CJC-1295 without DAC" refer to the same compound: the tetrasubstituted GRF 1-29 analog with D-Ala², Gln⁸, Ala¹⁵, and Leu²⁷ substitutions, without the albumin-binding Drug Affinity Complex. The terminology varies by vendor, but the molecule is identical. Strictly speaking, "CJC-1295" technically refers to the DAC version (the compound ConjuChem developed), and calling the no-DAC version "CJC-1295" is a naming convention the market adopted, not a scientifically accurate designation.

Does CJC-1295 with DAC cause receptor downregulation?

This is a theoretical concern, not a proven effect. Ionescu & Frohman's 2006 study showed that GH pulsatility was preserved after CJC-1295 DAC injection, and the Teichman et al. study found cumulative (not diminishing) IGF-1 effects over 28–49 days — suggesting no meaningful desensitisation within that timeframe. However, no studies have assessed periods beyond 49 days, so the long-term question remains genuinely open. The precautionary preference for no-DAC among practitioners is driven by this uncertainty, not by positive evidence of downregulation.

Can you use CJC-1295 with DAC and without DAC in the same protocol?

This is pharmacologically redundant — both activate the same GHRH receptor on pituitary somatotropes. Using both simultaneously would provide overlapping stimulation without meaningful additive benefit, since the receptor is already being engaged by one agonist. Practitioners choose one version based on whether they want pulsatile control (no DAC, typically stacked with a GHRP) or sustained convenience (with DAC, typically used standalone or with less frequent GHRP dosing), not both.

Why was the CJC-1295 clinical trial stopped?

During Phase II trials of CJC-1295 with DAC for lipodystrophy and GH deficiency, one trial subject died. The attending physician determined the most likely cause was asymptomatic coronary artery disease with plaque rupture and occlusion — an event assessed as unrelated to CJC-1295 treatment. ConjuChem Biotechnologies terminated research as a precaution. No further clinical trials have been initiated for either version of CJC-1295 by any sponsor, and ConjuChem no longer operates as an active pharmaceutical company. The terminated trial effectively ended the clinical development pathway for what was, at the time, the most promising long-acting GHRH analog.

Which version should I choose for stacking with ipamorelin?

CJC-1295 without DAC (Mod GRF 1-29) is the standard choice for ipamorelin stacking. Its short half-life (~30 minutes) enables precise co-timing with the GHRP injection — both peptides produce a GH pulse that peaks within 15–30 minutes, creating a synergistic amplification through simultaneous activation of the GHRH receptor (CJC-1295) and the ghrelin/GHS receptor (ipamorelin). The DAC version's sustained activity makes pulse timing irrelevant and may reduce per-injection synergistic benefit, as the pituitary is already under continuous GHRH drive.

This article is for educational and informational purposes only and does not constitute medical advice. Peptides discussed may be investigational compounds not approved by the FDA for human use. Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.