CJC-1295 No/DAC

A tetrasubstituted GHRH(1-29) analogue, also called Modified GRF 1-29, studied for short-acting, pulsatile growth-hormone release that tracks the pituitary's own rhythm more closely than the long-acting DAC form.

What it is

CJC-1295 No/DAC, known in the peptide literature as Modified GRF 1-29 (originally described as tetrasubstituted GRF 1-29), is a synthetic 29-amino-acid analogue of growth-hormone-releasing hormone. It reproduces the first 29 residues of GHRH, the shortest fragment that keeps full biological activity, and carries four amino-acid substitutions on that backbone that slow enzymatic breakdown without adding the maleimide Drug Affinity Complex (DAC) found on the long-acting version. The four changes are at positions 2, 8, 15 and 27: a D-alanine at position 2 to blunt dipeptidyl peptidase-4 cleavage, plus stabilising substitutions at 8, 15 and 27. The result is a peptide that resists degradation enough to extend its working half-life to roughly 30 minutes, versus under 10 minutes for native GHRH(1-29), while still clearing far faster than the DAC-bearing analogue.

Because it lacks the albumin-binding DAC linker, CJC-1295 No/DAC does not accumulate in circulation and does not produce the multi-day GH plateau associated with the DAC form. That short window is the point of the molecule: it is the GHRH arm of many secretagogue pairings and is studied on its own when a release pattern close to the body's endogenous pulses is the modelling goal. Supplied strictly for laboratory research use only, not for human or veterinary use.

How it works

Modified GRF 1-29 binds the GHRH receptor (GHRHR), a class B G-protein-coupled receptor expressed on somatotroph cells of the anterior pituitary. Receptor engagement couples through G_s to activate adenylate cyclase, raising intracellular cAMP and activating protein kinase A. That cascade promotes calcium influx and drives both the synthesis and the pulsatile secretion of growth hormone, working through the pituitary-specific transcription factor Pit-1 that governs GH gene expression. It is the same receptor and the same signalling route used by native GHRH; the substitutions change pharmacokinetics, not the mechanism.

Downstream, the pulse of GH released into circulation acts on the liver and peripheral tissues to raise insulin-like growth factor 1 (IGF-1), the principal mediator of GH's anabolic and growth effects. Crucially, because the peptide works upstream at the pituitary rather than replacing GH directly, GH output stays subject to normal negative feedback from somatostatin and IGF-1, so the secretory rhythm is preserved rather than overridden. This is what distinguishes a GHRH secretagogue from exogenous GH, which suppresses the endogenous axis and flattens pulsatility.

What the research shows

Direct human pharmacokinetic and pharmacodynamic data for the CJC-1295 molecule come chiefly from two 2006 studies in the Journal of Clinical Endocrinology & Metabolism on the DAC-conjugated form, which share the same GHRH(1-29) pharmacophore as the No/DAC peptide. Teichman and colleagues gave single subcutaneous doses to healthy adults and recorded dose-dependent rises in mean plasma GH of 2- to 10-fold lasting six days or more, and mean IGF-1 rises of 1.5- to 3-fold lasting 9 to 11 days, with an estimated half-life of 5.8 to 8.1 days for the DAC form. Ionescu and Frohman then showed that even under this sustained stimulation, GH secretion remained pulsatile: trough GH rose about 7.5-fold while pulse frequency and amplitude were unchanged, mean GH rose 46% and IGF-1 rose 45%. The long DAC half-life is exactly the property the No/DAC form removes: stripping the DAC shortens the working half-life to roughly 30 minutes, giving the short, sharp pulses researchers use when a near-physiological release profile is wanted.

Compared with the DAC form

The two molecules share an identical GHRH(1-29) core and act through the same pituitary GHRH receptor; the only structural difference is the DAC (a maleimidopropionic acid group) that lets the DAC version bind circulating albumin and persist for days. That single change reshapes the pharmacology. The DAC form produces a sustained bleed of GH-releasing signal, raising GH and IGF-1 for a week or more from one dose (Teichman 2006), and although pulsatility is preserved, the baseline sits elevated across the whole interval (Ionescu 2006). The No/DAC form, cleared in about half an hour, instead produces discrete pulses that rise and return toward baseline, which is why investigators reach for it when the aim is to mimic the timing of the body's own GHRH signalling or to pair a clean GHRH pulse with a ghrelin-mimetic secretagogue.

Side Effects

No controlled human trial has specifically characterized the safety or tolerability of CJC-1295 without DAC (Mod-GRF 1-29), so its side-effect profile is not directly established. The entries below draw on the closest available evidence: the human pharmacology study of CJC-1295 with DAC (Teichman 2006), the labeled adverse reactions of the related GHRH(1-29) analog sermorelin (marketed as Geref), and the known effects of growth-hormone excess seen with GH-raising therapies. Items marked "class-based" are extrapolations from these related agents and the GHRH-analog class, not findings observed with Mod-GRF 1-29 itself.

These entries should be read as class-level expectations rather than a verified profile for Mod-GRF 1-29 specifically. No dedicated human safety study of CJC-1295 without DAC exists, so its long-term tolerability, immunogenicity, and effects on glucose metabolism remain uncharacterized.

At a glance

Molecular formula C₁₅₂H₂₅₂N₄₄O₄₂, confirmed against PubChem CID 91976842.

Dosing

There is no dedicated human dosing study for CJC-1295 without DAC (Modified GRF 1-29), and no approved regimen exists for it. The figures below are borrowed from two related molecules that have been studied in people: CJC-1295 with DAC, the long-acting version tested in a Phase 1 trial, and sermorelin (Geref), a GHRH(1-29) analog once approved for pediatric growth hormone deficiency. These are study and analog doses reported for laboratory and clinical research context, not instructions for use.

None of these figures come from Mod-GRF 1-29 itself, and no established regimen exists for it in humans. The CJC-1295 with DAC numbers reflect a long-acting variant, and the sermorelin numbers reflect a different, shorter analog approved for a pediatric indication, so neither transfers directly. All of this is presented for laboratory research use only.

Preparing it

The vial ships as a lyophilized powder and is reconstituted with bacteriostatic water (or sterile water for single-session work) before use. Pick a diluent volume that gives a concentration you can read cleanly on a U-100 syringe. Reconstituted peptide is typically kept at 2-8 C. See reconstitution for the method and the concentration formula for the maths.

Where to go next

Last updated on July 3, 2026