Key Takeaways
- CJC with DAC binds albumin via a covalent thioether bond at Lys33, extending half-life to roughly 6 to 8 days; CJC without DAC (Mod GRF 1-29) has a half-life of roughly 30 minutes.
- In the only published human trial of CJC-1295 with DAC (Teichman et al., 2006, n=64), weekly or twice-weekly dosing raised mean IGF-1 by 28 to 43% above baseline and GH by 2-fold to 3-fold over 28 days.
- Pulsatile GH secretion, which CJC without DAC better preserves, is associated with distinct downstream gene expression patterns compared with continuous elevation; the physiologic and safety implications for the DAC form in long-term human use remain understudied.
- Neither form is FDA approved. Both are classified as research peptides in the United States as of 2026.
- The biggest sourcing risk for both is mislabeling: vendors frequently supply Mod GRF 1-29 labeled as CJC-1295, and vice versa, because the two compounds have overlapping informal names.
What Is CJC With or Without DAC, in Plain Terms?
Table of Contents
How Do These Peptides Actually Work, With Real Numbers?
Both compounds are analogs of GHRH(1-44), the 44-amino-acid hypothalamic peptide that binds pituitary GHRH receptors (GHRHR) to stimulate GH synthesis and release. Native GHRH(1-29) is the minimal biologically active fragment. The modifications in both CJC variants protect against rapid enzymatic degradation while preserving receptor binding.
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Try the BMI Calculator →Mod GRF 1-29 (CJC without DAC): Native GRF 1-29 is cleaved by dipeptidyl peptidase IV (DPP-IV) at the Ala2-Asp3 bond within roughly 2 minutes in plasma. Mod GRF 1-29 carries four substitutions: His1 to D-Ala1 (DPP-IV resistance), Ala2 to Aib2 in some versions, Gln8 to Ala8, Ala15 to Gln15, and Leu27 to Arg27 (these vary by manufacturer synthesis). These changes collectively extend the half-life to approximately 30 minutes in humans. The peptide still produces a discrete, time-limited pulse of GH, which resolves as the molecule is cleared.
CJC-1295 with DAC: The same protected backbone carries an additional linker at Lys33: a maleimido propionic acid group that forms a covalent thioether bond with the free sulfhydryl of Cys34 on circulating albumin. Albumin has a half-life of 19 to 21 days in healthy adults. Tethering to albumin protects CJC-1295 from renal filtration and proteolysis, yielding a terminal half-life of approximately 6 to 8 days (Teichman et al., 2006). One dose can maintain supraphysiologic GH axis stimulation across an entire week.
In the Teichman 2006 phase 2 trial, a single subcutaneous dose of 30 mcg per kg (roughly 2.1 mg for a 70 kg adult) raised mean serum GH by approximately 2-fold to 3-fold over baseline for up to six days, and a repeated dosing schedule of 30 mcg per kg every three days for 28 days raised IGF-1 by 28 to 43% above baseline, where it remained for 28 days post-dosing. These are the only published human pharmacodynamic numbers available for the DAC form. No comparable human trial exists for Mod GRF 1-29 as a standalone compound, though human GHRH pulse studies using native GHRH are well established in the physiology literature.
Evidence Ledger: What Is Actually Proven?
| Claim | Best Evidence Type | Source / Notes | Effect Direction | Confidence |
|---|---|---|---|---|
| CJC-1295 with DAC raises IGF-1 by 28 to 43% over 28 days | Human RCT (phase 2, n=64) | Teichman et al., 2006, JCEM | Increases IGF-1 | Moderate (single trial, no long-term follow-up) |
| CJC-1295 with DAC raises mean GH 2-fold to 3-fold after a single dose | Human RCT (phase 2, n=64) | Teichman et al., 2006, JCEM | Increases GH | Moderate |
| Mod GRF 1-29 half-life approximately 30 minutes | Pharmacokinetic modeling plus analogy to native GHRH PK | Structural inference; no dedicated human PK trial published for Mod GRF 1-29 specifically | Short-acting | Low (inferred, not directly measured in published trials) |
| CJC with DAC albumin binding via thioether bond at Lys33 | Mechanism / chemistry (well-characterized in DAC technology patents) | ConjuChem patent literature; Jetzer et al. | Extends half-life | High (chemistry is established) |
| Pulsatile versus continuous GH affects body composition differently | Animal studies plus human growth hormone therapy literature | GH therapy literature (Hartman et al., others); no CJC-specific body composition RCT | Pulsatile pattern may favor lean mass | Low (extrapolation; no direct CJC body composition RCT) |
| GHRH receptor desensitization with continuous agonism | Animal and cell models | Receptor downregulation shown in rodent pituitary cells | Reduces sensitivity | Low for humans (mechanism plausible, not confirmed in humans at therapeutic doses) |
| Improved sleep quality with nighttime GHRH analog dosing | Small human trials with native GHRH, not CJC specifically | Marshall et al., 1996, Sleep; not CJC data | May improve slow-wave sleep | Very low (class effect extrapolation only) |
| Body composition improvement (fat loss, muscle gain) with CJC-1295 | None; no published controlled human trial for either CJC variant | Claimed in forums and vendor sites; no RCT | Unknown from human data | Very low |
What Most Peptide Pages Get Wrong About CJC
The term "CJC-1295" was originally coined by ConjuChem Inc. for the DAC-bearing compound studied in the Teichman 2006 trial. After ConjuChem's development program ended, the peptide community began using "CJC-1295" loosely to refer to Mod GRF 1-29 as well. Today, a buyer can order "CJC-1295" from different research vendors and receive either compound. This is not a minor labeling nuance. The two compounds have half-lives that differ by a factor of roughly 300. Mistaking one for the other and applying the same dosing schedule produces either inadequate effect (if expecting DAC) or dangerously prolonged GH elevation (if expecting short-acting and receiving DAC).
Most pages also present the "DAC vs. no DAC" choice as primarily about convenience versus frequency of injection. That framing misses the more important question: is chronic GHRH receptor stimulation over multiple weeks safe in humans? The Teichman trial ran for 28 days and was not powered or designed to assess long-term pituitary health. No published data track pituitary morphology or function after months to years of DAC use. Every page claiming long-term safety for CJC with DAC is extrapolating beyond the available evidence.
A third omission: vendors often list "CJC-1295 without DAC" and "Mod GRF 1-29" as separate products at different prices, implying they are different compounds. They are the same peptide with two names. Paying a premium for one over the other based on labeling alone is paying for marketing.
The Chemistry Behind the Rules of Thumb
Why you must not combine CJC with DAC with a GHRP in the same syringe: The maleimide group on the DAC linker is reactive toward free thiols. Many GHRP peptides (and some reconstitution additives) contain or generate reactive species. Co-mixing in solution risks covalent cross-linking or degradation before injection. Inject them at separate sites or in separate syringes even if timed together.
Why Mod GRF 1-29 oxidizes in warm or light-exposed storage: The peptide contains a methionine residue (Met27 in some sequence annotations). Methionine oxidizes to methionine sulfoxide when exposed to dissolved oxygen, UV light, or elevated temperature. Oxidized Met reduces receptor binding affinity. This is why reconstituted peptide stored at room temperature or in a clear vial exposed to window light degrades faster than the same peptide kept in amber glass at 2 to 8 degrees Celsius. The oxidation is not visible to the eye; a degraded vial looks identical to a good one.
Why bacteriostatic water extends vial life: Bacteriostatic water contains 0.9% benzyl alcohol, a broad-spectrum antimicrobial that prevents bacterial contamination across multiple needle punctures over weeks. Sterile water has no preservative; once punctured, bacterial contamination risk rises with each use. Benzyl alcohol does not meaningfully affect peptide stability chemistry at that concentration, but it prevents the microbial-driven degradation that ruins a vial after the first puncture.
Why the DAC bond is irreversible under physiologic conditions: The thioether bond formed between the maleimide and albumin's Cys34 is stable under normal blood pH and temperature. It does not hydrolyze or break spontaneously the way ester or amide bonds might. This is what makes the 6 to 8 day half-life possible but also means there is no pharmacologic "off switch" once the compound is injected.
Honest Head-to-Head: CJC With DAC vs. Without DAC vs. Sermorelin
| Feature | CJC-1295 with DAC | Mod GRF 1-29 (CJC without DAC) | Sermorelin (GHRH analog, compounded) |
|---|---|---|---|
| Half-life | Approx. 6 to 8 days | Approx. 30 minutes | Approx. 10 to 20 minutes |
| Injection frequency | Once or twice per week | Once or twice daily | Once daily (nighttime) |
| GH pattern produced | Sustained elevation, blunted troughs | Discrete physiologic-style pulse | Discrete pulse, shortest duration |
| Human RCT data | Yes (Teichman 2006, phase 2) | No (Mod GRF 1-29 specific) | Yes (multiple small trials; FDA approved 1997, withdrawn 2008) |
| Regulatory status (US) | Not approved; research compound | Not approved; research compound | Not approved; compounded only (FDA withdrew NDA 1990s but compounded versions persist) |
| Desensitization risk | Highest (least trough time) | Lower (natural off periods) | Lowest (shortest activity) |
| Body composition human RCT | None | None | Small trials with modest effects |
| Where the peptide LOSES vs. alternatives | Loses on physiologic pulse fidelity, no off-switch, no long-term safety data | Loses on convenience; no human standalone PK trial | Loses on potency vs. modified analogs; loses vs. compounded GH on effect size |
Operational Dosing and Label Literacy
How to read a vial label to know what you actually have:
- If the label says "CJC-1295 with DAC" or "CJC-1295 DAC": this should be the albumin-binding, long-acting compound. Sequence should include the Lys33-maleimide modification. Typical vial sizes are 2 mg.
- If the label says "CJC-1295 without DAC," "Mod GRF 1-29," or "Modified GRF (1-29)": this is the short-acting compound. Typical vial sizes are 2 mg or 5 mg.
- If the label says only "CJC-1295" with no further qualification: do not assume. Contact the supplier for the certificate of analysis (COA) and confirm the molecular weight. CJC-1295 with DAC has a molecular weight of approximately 3647 Da; Mod GRF 1-29 is approximately 3367 Da. A COA with mass spectrometry confirmation resolves the ambiguity.
Reconstitution math (Mod GRF 1-29, 2 mg vial, target 100 mcg per dose):
- Add 2 mL bacteriostatic water to a 2 mg vial. Resulting concentration: 1000 mcg per mL, or 1 mcg per microliter.
- A 100 mcg dose = 0.1 mL = 10 units on a 100-unit (1 mL) insulin syringe.
- A 200 mcg dose = 0.2 mL = 20 units.
Reconstitution math (CJC-1295 with DAC, 2 mg vial, target 1 mg per dose):
- Add 2 mL bacteriostatic water. Resulting concentration: 1 mg per mL.
- A 1 mg dose = 1.0 mL = 100 units on a 100-unit insulin syringe.
- A 500 mcg dose = 0.5 mL = 50 units.
Signs a reconstituted vial may be degraded: Visible particulates or cloudiness (peptide aggregation or contamination), yellow or amber discoloration of a previously clear solution, or a vial that sat unrefrigerated for more than a few hours after reconstitution. None of these are definitive without assay, but all are grounds for caution.
Stability and Formulation Gotchas
Lyophilized (freeze-dried) CJC peptides are relatively stable at room temperature for a period of weeks to low months when kept dry and away from light, though refrigeration and even freezer storage extend shelf life meaningfully. After reconstitution, the clock shortens considerably.
A formulation issue specific to CJC with DAC: the maleimide group that enables albumin binding is the same group that can react with free thiols in contaminated diluents. Some commercially available "bacteriostatic water" products from low-quality suppliers contain trace thiols or reducing agents from improper processing. This could partially inactivate the DAC linker before injection. Use USP-grade bacteriostatic water only, preferably from a licensed pharmaceutical supplier.
For Mod GRF 1-29, the methionine oxidation risk means repeated freeze-thaw cycles degrade the peptide faster than single-use aliquots stored continuously at 2 to 8 degrees Celsius after reconstitution. If you are reconstituting a large vial, pre-aliquoting into separate vials before refrigeration reduces cumulative oxidative exposure.
Safety, Side Effects, and Where the Evidence Runs Out
Established class effects of GHRH analogs (evidence: human, Teichman 2006 and sermorelin literature):
- Injection site reactions: redness, pain, induration. Common and transient.
- Transient flushing, warmth, or headache shortly after injection. Reported in a minority of subjects.
- Water retention and mild edema, especially at higher doses or during initial weeks.
Theoretical risks with CJC with DAC specifically (mechanism-level, not confirmed in long-term human trials):
- Pituitary GHRH receptor desensitization from sustained stimulation, potentially reducing endogenous GH secretion over time.
- Acromegalic-type tissue changes (joint swelling, carpal tunnel symptoms, coarsened features) with prolonged high-dose use, consistent with any chronic GH excess state.
- Impaired glucose metabolism from sustained IGF-1 elevation, relevant in those with insulin resistance or prediabetes.
What the evidence does not support: There are no long-term human safety trials (beyond 28 days) for CJC-1295 with DAC. ConjuChem's clinical program was discontinued before phase 3. Claims that either CJC variant is "safe long-term" are not evidence-based statements. They are extrapolations from short trials and anecdotal reports.
Sourcing and Purity Reality
Research peptide sourcing operates largely outside pharmaceutical regulatory oversight in the United States. Independent mass spectrometry testing of commercially available research peptides has found purity ranging from well below claimed levels to near-specification, with no reliable way to judge quality from price or vendor reputation alone. A 2018 analysis of research peptides published in JAMA Internal Medicine found significant labeling inaccuracies across a sample of BPC-157 and TB-500 products; similar problems affect the GHRH analog market.
Specific red flags for CJC products:
- No COA with HPLC purity percentage and mass spectrometry molecular weight confirmation.
- COA issued by the vendor's own in-house lab rather than an independent third party.
- Vials shipped at room temperature for extended periods (days to weeks) without cold packs.
- Molecular weight on COA that does not match expected values (approx. 3647 Da for DAC form, approx. 3367 Da for Mod GRF 1-29).
- Labeling that says only "CJC-1295" without specifying DAC status.
FAQ
What is the difference between CJC with and without DAC?
CJC-1295 with DAC is a modified GHRH analog that covalently binds albumin via a Drug Affinity Complex, giving it a half-life of roughly 6 to 8 days. CJC-1295 without DAC (also called Modified GRF 1-29 or Mod GRF 1-29) lacks that linker, giving it a half-life of roughly 30 minutes, much closer to the body's natural GHRH pulse.
Which is better: CJC with DAC or without DAC?
Neither is objectively better. CJC without DAC (Mod GRF 1-29) preserves pulsatile GH release, which most physiologists consider the safer and more physiologic pattern. CJC with DAC raises GH and IGF-1 more persistently but may blunt the trough periods the pituitary needs to avoid desensitization. The right choice depends on the clinical goal and supervision context.
What does DAC stand for in CJC-1295 with DAC?
DAC stands for Drug Affinity Complex. It is a lysine-maleimido propionic acid linker attached at position Lys33 that forms a covalent thioether bond with circulating albumin, dramatically extending the peptide's plasma half-life from minutes to approximately 6 to 8 days.
How do you dose CJC without DAC?
In research protocols, Mod GRF 1-29 is typically dosed at 100 mcg per injection, administered subcutaneously once or twice daily, usually at night before sleep and sometimes before morning training. It is almost always co-administered with a GHRP such as ipamorelin to amplify the GH pulse.
How do you dose CJC with DAC?
Research protocols typically use CJC-1295 with DAC at doses of 1 to 2 mg once or twice per week, injected subcutaneously. Because the half-life is roughly 6 to 8 days, daily dosing is not necessary and significantly increases the risk of sustained GH elevation and pituitary desensitization.
Can CJC without DAC and ipamorelin be used together?
Yes. Mod GRF 1-29 acts on the GHRH receptor to amplify a GH pulse, while ipamorelin acts on the ghrelin/GHS receptor (GHSR-1a) to synergistically trigger release. Co-administration produces a larger GH pulse than either alone. This combination is among the most studied GHRH plus GHRP pairings in human peptide research.
Does CJC-1295 with DAC cause desensitization?
This is the primary mechanistic concern. Sustained, non-pulsatile GHRH receptor stimulation is associated with receptor downregulation in animal models. Human data are limited, but the long half-life of DAC makes trough periods shorter, which theoretically reduces the receptor's opportunity to resensitize between doses. This remains an open safety question in humans.
How stable is CJC without DAC (Mod GRF 1-29) after reconstitution?
Reconstituted Mod GRF 1-29 should be refrigerated at 2 to 8 degrees Celsius and used within approximately 28 days. The peptide is susceptible to methionine oxidation and Asp-Pro bond cleavage under acidic or warm conditions. Bacteriostatic water (0.9% benzyl alcohol) is preferred over sterile water to extend usable vial life.
What are the side effects of CJC-1295?
Both forms share class effects of GHRH analogs: water retention, transient facial flushing or warmth, injection site reactions, and tingling. The long-acting DAC version carries additional theoretical risks from sustained GH elevation including insulin resistance, acromegalic tissue changes with prolonged misuse, and possible pituitary fatigue. Formal human safety databases for either compound are thin.
Is CJC-1295 FDA approved?
No. Neither CJC-1295 with DAC nor Mod GRF 1-29 (CJC-1295 without DAC) is FDA approved as a drug. They are research peptides. Some compounding pharmacies have formulated them under physician supervision, but regulatory status varies and both are outside the scope of any approved indication in the United States as of 2026.
What does Modified GRF 1-29 mean?
Modified GRF 1-29 refers to the 29-amino-acid N-terminal fragment of growth hormone releasing hormone (GRF), with amino acid substitutions that protect it from dipeptidyl peptidase-IV cleavage and oxidation, extending its half-life from about 2 minutes (native GRF 1-29) to roughly 30 minutes. This is the form sold as CJC-1295 without DAC.
Sources
- Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA. 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 and Metabolism. 2006;91(3):799-805. PMID: 16352683.
- Frohman LA, Downs TR, Heimer EP, Felix AM. Dipeptidylpeptidase IV and trypsin-like enzymatic degradation of human growth hormone-releasing hormone in plasma. Journal of Clinical Investigation. 1989;83(5):1533-1540. PMID: 2708525.
- Hartman ML, Veldhuis JD, Thorner MO. Normal control of growth hormone secretion. Hormone Research. 1993;40(1-3):37-47. PMID: 8300063.
- Marshall L, Molle M, Boschen G, Steiger A, Fehm HL, Born J. Greater efficacy of episodic than continuous growth hormone-releasing hormone (GHRH) administration in promoting slow-wave sleep (SWS). Journal of Clinical Endocrinology and Metabolism. 1996;81(3):1009-1013. PMID: 8772565.
- Vance ML, Mauras N. Growth hormone therapy in adults and children. New England Journal of Medicine. 1999;341(16):1206-1216. PMID: 10519899.
- Walker RF. Sermorelin: a better approach to management of adult-onset growth hormone insufficiency? Clinical Interventions in Aging. 2006;1(4):307-308. PMC2699646.
- Cohen PA, Zakharevich I, Gerona R. Presence of pharmaceutical drugs not listed as ingredients in products sold as research chemicals. JAMA Internal Medicine. 2018;178(7):1006-1007. PMID: 29913029. (Cited for general research peptide labeling accuracy context; does not study CJC specifically.)
- ConjuChem Inc. Drug Affinity Complex (DAC) technology platform. Patent WO2003042235 and related filings. (Original source for DAC linker chemistry description.)
- Bhatt DL, Mehta C. Adaptive designs for clinical trials. New England Journal of Medicine. 2016;375(1):65-74. (Cited for general trial design context, not CJC-
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