Overview

CJC-1295 no DAC — most rigorously called “Modified GRF (1-29)” or “Mod-GRF-1-29” in the primary chemistry literature — is a short-acting GHRH analog closely related to Sermorelin. It retains the 29-residue N-terminal GHRH fragment but carries four amino-acid substitutions designed to slow enzymatic degradation: D-Ala at position 2, Gln at position 8, Ala at position 15, and Leu at position 27.

The compound is distinguished from CJC-1295 DAC — which shares the same 4-substitution backbone but is additionally conjugated with a maleimidopropionic-acid group (“drug affinity complex”, DAC) that binds covalently to serum albumin. That conjugation gives DAC-CJC-1295 a serum half-life on the order of days, while the “no DAC” variant discussed on this page has a functional half-life on the order of 30 minutes and produces pulsatile rather than tonic GHRH-receptor engagement.

There are no formally published Phase 1–3 trials of the “no DAC” (Mod-GRF-1-29) variant in the peer-reviewed literature that match the rigour of the DAC-variant publications. Most of the human-relevant characterisation is extrapolated from the closely-related DAC-CJC-1295 pharmacology work and from the extensive GHRH(1-29) literature.

Mechanism (as reported in the literature)

  • GHRH-receptor agonism. Like sermorelin, tesamorelin, and DAC-CJC-1295, Mod-GRF-1-29 binds the pituitary GHRH receptor and stimulates pulsatile release of endogenous growth hormone.
  • Degradation-resistant backbone. The four substitutions (positions 2, 8, 15, 27) are reported to slow dipeptidyl-peptidase-IV and endopeptidase-mediated cleavage relative to unmodified GHRH(1-29), extending the effective GHRH-receptor exposure window from a few minutes to roughly half an hour.
  • Absence of DAC conjugation. Without the maleimidopropionic-acid moiety, the compound does not bind albumin and does not develop the multi-day plasma exposure characteristic of DAC-CJC-1295. The intended pharmacological character is pulsatile GH release closer to physiological GHRH biology.
  • Ghrelin-mimetic pairing. Research protocols often report co-administration with a selective GH-secretagogue such as Ipamorelin to combine independent stimulation of the somatotroph via GHRH and ghrelin-receptor pathways.

Research findings

  • DAC-variant pharmacology (Teichman et al., 2006). The pivotal characterisation of CJC-1295 DAC in healthy adults reported sustained elevations in GH and IGF-1 after weekly dosing, along with the pharmacokinetic details that motivated later contrast with the no-DAC variant. Published in the Journal of Clinical Endocrinology & Metabolism, 91(3). PMID 16352683.
  • DAC-variant elderly cohort (Ionescu & Frohman, 2006). Reported pulsatile-versus-tonic GH release contrasts that motivate the “no DAC” design rationale. JCEM, 91(12), 4792–4797.
  • Sermorelin baseline (Corpas et al., 1992; Vittone et al., 1997). Serve as the reference points for what unmodified GHRH(1-29) achieves in older adults, since the “no DAC” variant is best understood as a stabilised sermorelin. PMIDs 1740455 and 9005974.
  • No standalone published trial of Mod-GRF-1-29. No dedicated clinical trial of the no-DAC variant with formal pharmacokinetic and endocrine endpoints has been identified in the published literature reviewed for this entry. Community protocols cite the DAC-variant paper and the sermorelin literature by extrapolation.

Common dosing (from published research protocols)

Community-referenced research protocols report 100–300 mcg subcutaneously per administration, with one to three administrations daily — often paired with a ghrelin-mimetic such as ipamorelin at the same site. A common convention is a bedtime dose to align with the nocturnal GH pulse, with optional additional doses distributed away from meals. These are ranges reported in the literature and community writeups, not recommendations.

Reconstitution

A 5 mg vial reconstituted with 2 mL of bacteriostatic water yields a 2,500 mcg/mL solution.

  • 100 mcg = 0.04 mL = 4 units on a U-100 insulin syringe
  • 200 mcg = 0.08 mL = 8 units
  • 300 mcg = 0.12 mL = 12 units

Storage

Lyophilised Mod-GRF-1-29 is reported as stable at refrigerated temperatures. Once reconstituted, it is generally reported to be stored at 2–8 °C for short-term use and at freezer temperatures for long-term storage; reported stability windows in the community peptide literature are broadly similar to sermorelin.

  • CJC-1295 DAC — the long-acting, albumin-binding variant; the primary contrast on pharmacokinetics.
  • Sermorelin — the unmodified GHRH(1-29) reference; useful for understanding what the four substitutions add.
  • Ipamorelin — a selective GH-secretagogue commonly paired with Mod-GRF-1-29 in reported research protocols.
  • Tesamorelin — an alternative stabilisation approach using an N-terminal acyl modification.

Common stacks

References

  • Teichman, S. L., et al. (2006). “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.” Journal of Clinical Endocrinology & Metabolism, 91(3), 799–805. PMID 16352683.
  • Ionescu, M., & Frohman, L. A. (2006). “Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog.” Journal of Clinical Endocrinology & Metabolism, 91(12), 4792–4797.
  • Corpas, E., et al. (1992). “Growth hormone-releasing hormone-(1-29) twice daily reverses the decreased GH and insulin-like growth factor-I levels in old men.” Journal of Clinical Endocrinology & Metabolism, 75(2). PMID 1740455.