CJC-1295 no DAC (Mod GRF 1-29)
Also known as: Mod GRF 1-29, Modified GRF, CJC-1295 without DAC, tetrasubstituted GRF(1-29)
Evidence: Preclinical
Overview
Tetrasubstituted GHRH(1-29) analog ([D-Ala2, Gln8, Ala15, Leu27]), the peptide part of CJC-1295 without its albumin-binding linker; no published study of this exact peptide, each substitution characterized separately.
'Mod GRF 1-29' is a community name for [D-Ala2, Gln8, Ala15, Leu27]-GHRH(1-29)-NH2, the GHRH portion of CJC-1295 without its C-terminal maleimide-lysine linker (Jette 2005). 'CJC-1295 no DAC' is a vendor coinage. No peer-reviewed study of this exact peptide was found. The substitutions are each characterized separately: D-Ala2 blocks dipeptidyl peptidase IV cleavage between residues 2 and 3 (Su 1991, porcine plasma) and raised the plasma half-time of GHRH(1-29) from 4.3 to 6.7 min in men (Soule 1994); Ala15 raises GHRH-receptor affinity 4-5 fold in vitro (Campbell 1991); replacing Asn8 removes the main deamidation site that degrades GHRH analogs in solution (Friedman 1991); Leu27 replaces oxidation-prone Met27. Human data on the related peptide come only from the DAC conjugate (Teichman 2006). Evidence level is preclinical.
Benefits
GH release expected from GHRH(1-29) pharmacology (no study of the exact peptide), DPP-IV resistance from D-Ala2 (porcine plasma; human PK of D-Ala2-GHRH(1-29)), higher receptor affinity from Ala15 (in vitro), reduced Asn8 deamidation from Gln8 (in vitro)
Dosing reference
- Research dose
- No human data for this peptide; research-community range 100-300 mcg SC per injection, 1-3x daily
- Range
- 100 to 300 mcg, 1-3x daily
- Reconstitution
- 2 mL bacteriostatic water
- Common vial sizes
- 2 mg, 5 mg
Subcutaneous in research use. The D-Ala2 substitution extends the plasma half-time of GHRH(1-29) only to about 7 min in men (Soule 1994), so each injection produces a single short GH pulse. GHRH plus GHRP synergy is documented in men for GHRH(1-44) with GHRP-6 (Bowers 1990), not for this peptide specifically.
Mechanism
Acts at the pituitary GHRH receptor like the parent GHRH(1-29). The four substitutions address GHRH's instability: D-Ala2 prevents dipeptidyl peptidase IV from removing the N-terminal dipeptide, the step that inactivates GHRH within minutes (Su 1991); Gln8 removes the asparagine whose deamidation degrades GHRH analogs in neutral solution (Friedman 1991); Ala15 increases receptor affinity by stabilizing the amphiphilic helix (Campbell 1991); Leu27 replaces an oxidizable methionine. In CJC-1295 this same peptide, with a linker added, activates the GHRH receptor while albumin-bound (Jette 2005). Synergy with GHRPs, which act through GHS-R1a, is documented for GHRH itself (Bowers 1990); the '2-3x' figure in the old record had no source.
Evidence
Preclinical: animal or in vitro data only
- No peer-reviewed study of this exact peptide was located (PubMed and Crossref searched October 2026)
- D-Ala2 substitution reduced metabolic clearance of GHRH(1-29) and raised its plasma half-time from 4.3 to 6.7 min in 10 normal men (Soule et al., 1994)
- D-Ala2 completely prevented cleavage between residues 2 and 3 in porcine plasma; Ala15 alone gave a small gain (Su et al., 1991)
- Ala15-substituted GHRH(1-29) analogs bound the GHRH receptor 4-5x more tightly in vitro (Campbell et al., 1991)
- The same tetrasubstituted peptide plus a maleimide-lysine linker is CJC-1295, which raised GH and IGF-1 for days in humans (Jette et al., 2005; Teichman et al., 2006)
- Human-trial status: none for this peptide; evidence is in vitro and animal work on the individual substitutions
References
- Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-lasting GRF analog. Jette L, Leger R, Thibaudeau K, et al., Endocrinology, 2005
- Incorporation of D-Ala2 in growth hormone-releasing hormone-(1-29)-NH2 increases the half-life and decreases metabolic clearance in normal men. Soule S, King JA, Millar RP, Journal of Clinical Endocrinology & Metabolism, 1994
- GRF analogs and fragments: correlation between receptor binding, activity and structure. Campbell RM, Lee Y, Rivier J, Heimer EP, Felix AM, Mowles TF, Peptides, 1991
- In vitro stability of growth hormone releasing factor (GRF) analogs in porcine plasma. Su CM, Jensen LR, Heimer EP, Felix AM, Pan YC, Mowles TF, Hormone and Metabolic Research, 1991
- Degradation of growth hormone releasing factor analogs in neutral aqueous solution is related to deamidation of asparagine residues. Replacement of asparagine residues by serine stabilizes. Friedman AR, Ichhpurani AK, Brown DM, et al., International Journal of Peptide and Protein Research, 1991
- 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. Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA, Journal of Clinical Endocrinology & Metabolism, 2006
- Growth hormone (GH)-releasing peptide stimulates GH release in normal men and acts synergistically with GH-releasing hormone. Bowers CY, Reynolds GA, Durham D, Barrera CM, Pezzoli SS, Thorner MO, Journal of Clinical Endocrinology & Metabolism, 1990
- Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency. Prakash A, Goa KL, BioDrugs, 1999
Side effects
No safety data exist for this exact peptide. For GHRH(1-29) itself, transient facial flushing and injection-site pain were the common trial adverse events (Prakash 1999). Head rush, water retention, joint aches and reduced insulin sensitivity are commonly reported (anecdotal).
Storage
- Storage
- Refrigerated (2-8°C)
- Lyophilized
- 24+ months at room temperature
- Reconstituted
- 28-30 days refrigerated
Pharmacology
- Half-life
- Not reported for this exact peptide; D-Ala2-GHRH(1-29) ~6.7 min (human, IV infusion; Soule 1994). The ~30 min figure is community lore
- Molecular weight
- 3367.9 Da
- Sequence
- Y[D-A]DAIFTQSYRKVLAQLSARKLLQDILSR[NH2]