CJC-1295 is a synthetic growth hormone-releasing hormone (GHRH) analog that has become one of the most widely studied peptides for GH optimization. However, it exists in two fundamentally different forms that require completely different dosing protocols — and confusing the two is one of the most common mistakes in peptide dosing. This guide covers both versions, explains when to use each, and provides precise dosing calculations.
CJC-1295 with DAC vs. Without DAC (Mod GRF 1-29)
The "DAC" in CJC-1295 stands for Drug Affinity Complex — a modification that dramatically changes the peptide's pharmacokinetics:
| Property | CJC-1295 with DAC | CJC-1295 without DAC (Mod GRF 1-29) |
|---|---|---|
| Half-life | 6-8 days | ~30 minutes |
| Dosing frequency | 1-2x per week | 1-3x per day |
| GH release pattern | Sustained elevation (blunted pulsatility) | Sharp pulses (mimics natural GH secretion) |
| IGF-1 increase | Significant sustained elevation | Moderate pulsatile elevation |
| Best for | Convenience, sustained GH levels | Natural GH pulse pattern, stacking with GHRPs |
| Typical vial size | 2mg or 5mg | 2mg or 5mg |
This distinction is critical. The DAC version creates a sustained, chronic elevation of GH levels — similar to a slow-release mechanism. The non-DAC version (Mod GRF 1-29) creates sharp, pulsatile GH release that more closely mimics the body's natural secretion pattern. Many researchers prefer the non-DAC version because pulsatile GH release is considered more physiological and may avoid receptor desensitization.
CJC-1295 with DAC: Dosing Protocol
Reconstitution
For a 2mg vial, add 1mL of bacteriostatic water for a concentration of 2mg/mL (2,000 mcg/mL). For a 5mg vial, add 2.5mL for the same concentration.
Dosing
| Protocol | Dose | Frequency | Notes |
|---|---|---|---|
| Standard | 1,000 mcg (1mg) | Once per week | Most common protocol in published research |
| Split dose | 500 mcg | Twice per week | More stable levels; reduces peak-trough variation |
| Conservative | 500 mcg | Once per week | Lower-dose starting point |
The landmark Teichman et al. (2006) study demonstrated that a single 30 mcg/kg dose of CJC-1295 with DAC increased mean GH levels 2-10 fold for 6 or more days and increased IGF-1 levels 1.5-3 fold for 9-11 days. The 1,000 mcg flat dose approximates this weight-based range for most adults.
CJC-1295 without DAC (Mod GRF 1-29): Dosing Protocol
The Saturation Dose Concept
Mod GRF 1-29 follows a saturation dose principle: GHRH receptors on the pituitary have a maximum binding capacity, and doses beyond this point do not proportionally increase GH release. Research suggests the saturation dose is approximately 1 mcg per kg of bodyweight.
| Body Weight | Saturation Dose | Common Flat Dose |
|---|---|---|
| 60 kg (132 lbs) | 60 mcg | 100 mcg |
| 80 kg (176 lbs) | 80 mcg | 100 mcg |
| 100 kg (220 lbs) | 100 mcg | 100 mcg |
Most research protocols use a flat dose of 100 mcg per injection, administered 1-3 times daily. This simplifies dosing while ensuring saturation for most body weights.
Timing Protocols
Because Mod GRF 1-29 has a ~30-minute half-life, timing matters significantly:
- Pre-bed dose: 100 mcg 30 minutes before sleep — synergizes with the natural nocturnal GH pulse
- Morning fasted dose: 100 mcg upon waking, before food — takes advantage of low insulin/glucose
- Post-workout dose: 100 mcg within 15 minutes post-training — coincides with exercise-induced GH secretion
Critical timing rule: Avoid dosing within 2 hours of eating. Elevated blood glucose and insulin significantly blunt the GH response to GHRH stimulation. Fasting or at minimum 2 hours post-meal is essential for optimal effect.
Reconstitution Calculator
For Mod GRF 1-29 at 100 mcg doses from a 2mg vial reconstituted in 1mL BAC water (2,000 mcg/mL):
- 100 mcg = 0.05 mL = 5 units on an insulin syringe
- Doses per 2mg vial: 20 doses
- At 2x daily: One vial lasts 10 days
- At 3x daily: One vial lasts ~7 days
Use our Reconstitution Calculator for custom vial sizes and concentrations.
Cycling Recommendations
- CJC-1295 with DAC: 8-12 weeks on, 4 weeks off. The sustained half-life means receptor desensitization is a greater concern with continuous use.
- Mod GRF 1-29 (no DAC): Can be used for longer periods (12-16 weeks) before cycling off, as the pulsatile release pattern reduces desensitization risk. Some protocols run 5 days on, 2 days off indefinitely.
FAQ: CJC-1295 Dosing
Which version should I use — DAC or no DAC?
This depends on research goals. CJC-1295 with DAC is simpler (weekly dosing) and produces sustained GH/IGF-1 elevation. Mod GRF 1-29 (no DAC) produces more natural pulsatile GH release and is preferred for stacking with GHRPs like Ipamorelin. Most researchers combining CJC-1295 with a GHRP choose the non-DAC version.
Can I use CJC-1295 with DAC and Ipamorelin together?
While some protocols combine them, this is controversial. CJC-1295 with DAC creates sustained GHRH signaling that may override the pulsatile benefit of adding a GHRP. Most researchers who want the CJC-1295 + Ipamorelin synergy use the non-DAC version (Mod GRF 1-29 + Ipamorelin), dosed together at the same time. See our Ipamorelin + CJC-1295 Combined Dosing Guide for that protocol.
What does "saturation dose" mean exactly?
Saturation dose refers to the amount of GHRH needed to fully occupy pituitary GHRH receptors. Beyond this point, additional peptide does not proportionally increase GH output — you get diminishing returns. For Mod GRF 1-29, this is approximately 1 mcg/kg bodyweight. Taking 200 mcg instead of 100 mcg does not double your GH release; it may only add 10-20% more while doubling your peptide usage.
Why can't I eat before or after injection?
Elevated blood glucose triggers insulin release, and insulin is a potent suppressor of growth hormone secretion. Studies have shown that even moderate carbohydrate intake can reduce GH response to GHRH by 50-80%. The 2-hour fasting window ensures low insulin levels during the GH pulse. Fat and protein have less impact than carbohydrates but can still blunt the response.
Sources and References
- Teichman SL, et al. "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." J Clin Endocrinol Metab. 2006.
- Frohman LA, et al. "Rapid enzymatic degradation of growth hormone-releasing hormone by plasma in vitro and in vivo to a biologically inactive product cleaved at the NH2 terminus." J Clin Invest. 1986.
- Ionescu M, Bhatt DL. "Pharmacological profile of CJC-1295, a long-acting growth hormone releasing hormone analog." Growth Horm IGF Res. 2006.
- Alba-Roth J, et al. "Arginine stimulates growth hormone secretion by suppressing endogenous somatostatin secretion." J Clin Endocrinol Metab. 1988.
- Bowers CY. "Growth hormone-releasing peptide (GHRP)." Cell Mol Life Sci. 1998.
This guide is for educational and research purposes only. CJC-1295 is not FDA-approved for any medical condition. Consult a qualified healthcare professional before beginning any peptide protocol. All dosing information is derived from published research data.