Also known as: Modified GRF(1-29), Mod GRF 1-29, GRF(1-29) NH2
Pulsatile growth hormone release, typically combined with a GHRP (ipamorelin)
Amount
100 mcg per injection (1-2 mcg/kg saturation dose)
Frequency
2-3 times daily
Duration
8-12 weeks
Route
SCSchedule
2-3 times daily
Timing
Before sleep (to amplify nocturnal GH surge), upon waking, and optionally mid-afternoon; must be on empty stomach (2-3 hours post-meal); avoid food for 30 min after injection
โ Rotate injection sites
Duration
8-12 weeks
Repeatable
Yes
Diluent: Bacteriostatic water
Storage: Store lyophilized peptide at -20C. Reconstituted solution should be stored at 2-8C and used within 14-21 days. Protect from light. Do not freeze reconstituted solution.
IGF-1
When: Baseline
Why: Primary pharmacodynamic marker
Fasting glucose and HbA1c
When: Baseline
Why: GH elevation can impair glucose tolerance
Fasting insulin
When: Baseline
Why: Baseline insulin sensitivity
Thyroid panel (TSH, Free T3, Free T4)
When: Baseline
Why: GH affects thyroid hormone conversion
CMP
When: Baseline
Why: Liver and kidney function
IGF-1
When: 4-6 weeks
Why: Confirm GH axis stimulation
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CJC-1295 without DAC, commonly referred to as Modified GRF(1-29) or Mod GRF 1-29, is a synthetic 29-amino acid peptide analog of growth hormone-releasing hormone (GHRH). It represents the active peptide component of the CJC-1295 platform without the Drug Affinity Complex (DAC) moiety that enables albumin binding. This distinction is pharmacologically critical: without the DAC, the peptide has a plasma half-life of approximately 30 minutes rather than 6 to 8 days, fundamentally changing its pharmacokinetic and pharmacodynamic profile.
The peptide is based on the first 29 amino acids of human GHRH, which constitute the minimum fragment required for full biological activity at the GHRH receptor. Four strategic amino acid substitutions at positions 2, 8, 15, and 27 have been incorporated to improve metabolic stability, particularly resistance to cleavage by dipeptidyl peptidase IV (DPP-IV), the primary enzyme responsible for rapid inactivation of native GHRH.
Modified GRF(1-29) is widely used in research settings, often in combination with ghrelin-mimetic peptides such as ipamorelin or GHRP-6, to study pulsatile growth hormone stimulation. The combination of GHRH analog and ghrelin-mimetic produces synergistic GH release that exceeds the effect of either compound alone, as they act through complementary receptor pathways.
CJC-1295 without DAC functions as a selective agonist of the GHRH receptor (GHRH-R), a G protein-coupled receptor expressed on somatotroph cells in the anterior pituitary gland. Binding to the GHRH-R activates the Gs-adenylate cyclase-cAMP-PKA signaling cascade, which promotes both the transcription of the growth hormone gene and the exocytotic release of stored GH-containing secretory granules.
The mechanism is identical to that of its DAC-conjugated counterpart and of native GHRH. The critical pharmacological difference lies in the duration of receptor engagement. Without albumin binding, the peptide is cleared from the circulation within approximately 30 minutes, producing a brief burst of GHRH receptor activation followed by rapid return to baseline. This creates a discrete, time-limited GH pulse that closely mimics the endogenous pulsatile pattern of GH secretion.
The GH-releasing effect of Modified GRF(1-29) is subject to physiological regulation by somatostatin, the hypothalamic inhibitor of GH release. During periods of high somatostatin tone (such as the hours after meals), the GH response to Modified GRF(1-29) is blunted. Conversely, during natural somatostatin troughs (such as during sleep), the GH response is enhanced. This somatostatin modulation preserves the pulsatile GH secretion pattern that is important for normal GH physiology.
The downstream effects of GH release stimulated by Modified GRF(1-29) include increased hepatic production of insulin-like growth factor 1 (IGF-1), stimulation of protein synthesis and muscle growth, promotion of lipolysis and fat oxidation, and enhancement of tissue repair processes. However, because the GH elevation is transient (lasting 1 to 2 hours per injection), the magnitude of these downstream effects is smaller than with sustained GH stimulation from CJC-1295 DAC or exogenous GH therapy.
The research base for Modified GRF(1-29) derives primarily from two sources: the broader GHRH analog literature, which includes extensive research on native GRF(1-29) (sermorelin) and its modified variants, and the CJC-1295 clinical program conducted by ConjuChem, which characterized the pharmacology of the base peptide sequence used in both the DAC and non-DAC forms.
The amino acid modifications in Modified GRF(1-29) were characterized in a series of structure-activity relationship studies that demonstrated the four substitutions (D-Ala2, Gln8, Ala15, Leu27) significantly improved metabolic stability while preserving full GHRH receptor agonist activity. The preclinical pharmacology of the modified sequence, including its GH-releasing activity in animal models, was published by Alba et al. (2006).
CJC-1295 without DAC is an investigational compound that has not been approved for clinical use by any regulatory agency. Unlike sermorelin, which had previous FDA approval as a diagnostic and therapeutic agent, Modified GRF(1-29) has not undergone independent clinical development separate from the CJC-1295 DAC program.
The short half-life of Modified GRF(1-29) necessitates multiple daily injections (typically 2 to 3 times daily) to maintain GH axis stimulation, which is a significant practical limitation compared to the weekly dosing of CJC-1295 DAC. However, the short half-life is also a safety advantage, as any adverse effects resolve rapidly upon discontinuation.
CJC-1295 without DAC is prohibited by the World Anti-Doping Agency (WADA) as a growth hormone secretagogue and is banned in competitive athletics.
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, published in Journal of Clinical Endocrinology and Metabolism (Teichman SL et al., 2006; PMID: 16352683):
Clinical study characterizing the pharmacology of the CJC-1295 peptide sequence (used in both DAC and non-DAC forms); demonstrated dose-dependent GH and IGF-1 stimulation in healthy adults.
Once-daily administration of CJC-1295, a long-acting growth hormone-releasing hormone (GHRH) analog, normalizes growth in the GHRH knockout mouse, published in American Journal of Physiology - Endocrinology and Metabolism (Alba M et al., 2006; PMID: 16822960):
Preclinical study demonstrating that once-daily CJC-1295 normalizes growth in GHRH knockout mice, confirming the biological activity of the modified GRF(1-29) peptide sequence in vivo.
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This website is for educational and informational purposes only. The information provided is not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare professional before using any peptide or supplement.
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