Mod GRF 1-29
CJC-1295 without DAC - a modified GHRH analogue with 4 amino acid substitutions for enhanced stability, producing physiological GH pulses when paired with a GHRP peptide.
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Compound Profile
Mod GRF 1-29
Key Data
Research reference only
Research Focus
Preclinical data
⚠ Research & Educational Use Only. Mod GRF 1-29 is a research chemical documented here for scientific education. All information references peer-reviewed literature and preclinical/clinical study data. Not for human consumption. Not medical advice. Consult a licensed researcher or healthcare professional before any laboratory use.
- Amplifies natural GH pulses while preserving physiological pulsatility - unlike CJC-1295 with DAC which causes continuous elevation
- 4 amino acid substitutions (at positions 2, 8, 15, and 27) provide resistance to enzymatic degradation vs. native GHRH
- Works synergistically with all GHRPs - GHRP-2, GHRP-6, Ipamorelin, Hexarelin
- Mod GRF 1-29 is not FDA-approved for human use. It is a research chemical for scientific study only.
Research At a Glance
- Amplifies natural GH pulses while preserving physiological pulsatility - unlike CJC-1295 with DAC which causes continuous elevation
- 4 amino acid substitutions (at positions 2, 8, 15, and 27) provide resistance to enzymatic degradation vs. native GHRH
- Works synergistically with all GHRPs - GHRP-2, GHRP-6, Ipamorelin, Hexarelin
- Preserves the somatostatin feedback loop - pulses occur naturally, maintaining GH axis sensitivity
In Plain English
Simple summaryMod GRF 1-29 is essentially CJC-1295 without the long-acting modification -- it's growth-hormone-releasing hormone with four amino acid substitutions that make it resistant to enzymatic breakdown, but it still clears your system in about 30 minutes. That short window is actually a feature for many researchers: you inject it alongside ipamorelin about 30 minutes before sleep or training, get a sharp GH pulse that mimics your body's natural rhythm, and then the peptide is gone. The pulsatile pattern this creates is considered more physiologic than the continuous elevation from the DAC version.
- Amplifies natural GH pulses while preserving physiological pulsatility - unlike CJC-1295 with DAC which causes continuous elevation
- 4 amino acid substitutions provide resistance to enzymatic degradation vs. native GHRH
- Works synergistically with all GHRPs - GHRP-2, GHRP-6, Ipamorelin, Hexarelin
The full scientific detail, mechanisms, citations, and dosing data, follows below.
What is Mod GRF 1-29?
Tap any underlined term for an instant definition.
Mod GRF 1-29 (Modified GRF 1-29, also known as CJC-1295 without DAC or simply "CJC without DAC") is a synthetic analogue of growth hormone-releasing hormone (GHRH), the hypothalamic peptide that triggers GH secretion from the anterior pituitary. It represents the first 29 amino acids of native GHRH - the biologically active fragment - modified at four positions to resist enzymatic degradation.
Native GHRH 1-29 (Sermorelin) has a half-life of only 2-10 minutes in serum due to rapid cleavage by dipeptidyl peptidase IV (DPP-IV) and other proteases. Mod GRF 1-29 was created by substituting amino acids at positions 2, 8, 15, and 27 with more stable alternatives. These substitutions make the peptide resistant to DPP-IV cleavage at the N-terminus (position 2 substitution) and reduce susceptibility to other proteases - extending the half-life to approximately 30 minutes while preserving high GHRH receptor affinity and biological activity.
The defining characteristic of Mod GRF 1-29 vs. CJC-1295 with DAC is the absence of the Drug Affinity Complex (DAC) - a lysine derivative that allows the peptide to bind covalently to albumin in the bloodstream. With DAC, the resulting half-life extends to 8-10 days and GH elevation becomes continuous. Without DAC (Mod GRF 1-29), the half-life is approximately 30 minutes, and the peptide produces discrete, physiological GH pulses.
Researchers working on GH axis physiology generally prefer Mod GRF 1-29 over CJC-1295 with DAC precisely because it preserves natural pulsatility. GH is normally secreted in discrete pulses 4-8 times per day, with the largest pulse occurring during deep sleep. This pulsatile pattern is important for maintaining sensitivity of GH receptors and avoiding desensitisation. CJC-1295 with DAC's continuous stimulation disrupts this pattern.
Mod GRF 1-29 is almost never used alone in research. When combined with a GHRP peptide (Ipamorelin, GHRP-2, GHRP-6, or Hexarelin), the result is a dramatic synergistic amplification of GH release that far exceeds either peptide alone. This is because the two classes target different regulatory mechanisms: Mod GRF 1-29 stimulates GH release via GHRH receptors, while GHRPs both directly stimulate GH secretion via GHS receptors AND suppress somatostatin (the GH inhibitory hormone). Together, they release the brake and press the accelerator simultaneously.
By the Numbers
Key Research Benefits
Documented effects observed in preclinical and clinical studies on Mod GRF 1-29. See all Growth Hormone Secretagogues peptides for comparison.
Common Stacks
Mod GRF 1-29 is frequently combined with the following peptides for synergistic effects. Click any peptide to compare profiles before deciding.
Tesamorelin's GHRH-driven visceral fat reduction stacks with AOD-9604's direct lipolytic mechanism for comprehensive abdominal fat targeting.
Both are GHRH analogs: tesamorelin is more potent and FDA-validated while CJC-1295 is more accessible for general research.
Side Effects & Risks
Adverse effects reported in the research literature. All data sourced from preclinical and clinical study reports. View all peptides' side effects →
Dosing Data from the Literature
Doses referenced below are sourced from published preclinical and clinical studies. Use the peptide dose calculator to convert these values to injection volume.
Mod GRF 1-29 is almost always used alongside a GHRP peptide. The standard research ratio is 1:1 (e.g., 100 mcg Mod GRF 1-29 + 100 mcg Ipamorelin per injection).
Standard research dose: 100 mcg per injection Frequency: 2-3 injections daily Common combinations: + Ipamorelin (cleanest, lowest side effects), + GHRP-2 (more potent), + GHRP-6 (maximal GH + appetite) Timing: upon waking (fasted), pre-workout, and pre-sleep Administer both peptides in the same injection or within 5 minutes of each other for synergistic GH pulse
Administration in Research Settings
Standard reconstitution and administration methodology for laboratory research use.
Reconstitute lyophilised Mod GRF 1-29 with bacteriostatic water. Administer subcutaneously using an insulin syringe. Can be mixed in the same syringe as the GHRP peptide for a single injection.
Inject in a fasted state for maximum GH response. Avoid significant carbohydrate or fat intake for 30 minutes before and after injection. Pre-sleep injection timing is particularly valuable for GH optimisation as it amplifies the nocturnal GH surge.
Medical Expert Videos
Physicians, researchers, and pharmacologists explain Mod GRF 1-29, covering mechanisms of action, clinical context, and study findings.
Videos sourced from YouTube search. KnowYourPeptide does not endorse any individual creator. For research education only.
The Bottom Line
Mod GRF 1-29 has a growing body of preclinical evidence and a well-characterised safety profile in research settings. The most-studied application is: amplifies natural gh pulses while preserving physiological pulsatility - unlike cjc-1295 with dac which causes continuous elevation.
The most commonly reported side effect in research subjects is water retention, particularly in the first weeks of use, from gh-mediated aldosterone. It is a research chemical, not approved for human use.
Frequently Asked Questions
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Quick Reference
How It Compares
CJC-1295 DAC does the same job but lasts 6–8 days from one injection. Mod GRF 1-29 is better for people who want to control timing and mimic natural pulsatile GH release. Sermorelin is the older clinical version with shorter stability -- Mod GRF 1-29 has superior pharmacokinetics.
Compare Mod GRF 1-29 side-by-sideResearch Use Only
This information is for educational research purposes only. This is not medical advice. Consult a qualified healthcare professional.