CJC-1295 at a glance. CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH) that has been studied in laboratory and preclinical settings for its ability to stimulate the growth hormone (GH) axis. It is a frequent subject of confusion because the name is applied to two structurally different research peptides: a form carrying a Drug Affinity Complex (DAC) and a form without it, often labeled Modified GRF 1-29. This overview explains the distinction and summarizes what published research has actually examined.
The Peptide Behind the Name
The parent molecule is a truncated fragment of human GHRH known as hGRF(1-29) — the first 29 amino acids, which retain the biological activity of the full 44-residue hormone. Native GHRH has a very short circulating half-life because the enzyme dipeptidyl peptidase-IV (DPP-IV) rapidly degrades it. Researchers developed analogs of hGRF(1-29) with amino-acid substitutions intended to resist that enzymatic breakdown while preserving receptor activity.
In the foundational characterization work, Jetté and colleagues synthesized maleimido derivatives of hGRF(1-29) and reported that a tetrasubstituted version they designated CJC-1295 showed enhanced stability against DPP-IV and remained detectable in plasma beyond 72 hours in rats. That paper is where the identifier “CJC-1295” formally originates in the peer-reviewed literature, according to PubMed (DOI).
The DAC (Albumin-Binding) Form
The defining feature of CJC-1295 with DAC is the Drug Affinity Complex: a maleimidopropionyl (an N-epsilon-3-maleimidopropionamide of lysine) group attached at the C-terminus. After administration, this reactive group forms a covalent bond with a free thiol (Cys34) on circulating serum albumin. The peptide effectively becomes attached to a large, long-lived carrier protein.
This bioconjugation is what dramatically extends the molecule’s presence in circulation. In a pharmacokinetic study in healthy adults, Teichman and colleagues estimated a half-life on the order of roughly 6–8 days and observed that GH and IGF-I markers remained elevated for extended periods after a single subcutaneous dose in that research setting (DOI). A follow-up analysis reported that GH secretion remained pulsatile even under this sustained GHRH stimulation, with basal (trough) GH levels increased (DOI). When research references “CJC-1295” in the context of a multi-day half-life, it is almost always this DAC-bearing form.
The No-DAC Form (Modified GRF 1-29)
CJC-1295 without DAC — commonly called Modified GRF 1-29 or mod-GRF(1-29) — is the same substituted hGRF(1-29) backbone but lacks the albumin-binding maleimide linker. Without the DAC group, there is no covalent conjugation to albumin, so this form does not acquire the extended circulating profile of the DAC version. Its behavior is expected to resemble that of short-acting GHRH analogs such as sermorelin rather than the multi-day kinetics documented for the DAC form.
This is the central accuracy point: the two should not be treated as interchangeable. The published human and animal pharmacokinetic data describing a half-life of several days apply to the DAC form. Applying those figures to the no-DAC peptide would misrepresent what the research shows. Much of the “CJC-1295 without DAC” terminology circulates in non-peer-reviewed sources, whereas the DAC molecule is the one characterized in the primary literature cited here.
What Research Has Examined About CJC-1295
Published investigations of the DAC form have looked at several distinct questions in controlled research contexts:
- Mechanism and stability: the albumin-bioconjugation strategy and resistance to DPP-IV degradation were characterized in vitro and in rats (DOI).
- Pharmacokinetics and hormone markers: dose-related changes in GH and IGF-I were measured in healthy adult volunteers (DOI).
- Secretory pattern: whether pulsatile GH release is preserved under continuous GHRH-analog stimulation (DOI).
- Animal growth models: effects of dosing intervals on growth normalization in GHRH-knockout mice (DOI).
- Candidate biomarkers: serum protein profile changes following administration in normal adults (DOI).
- Analytical detection: because covalent albumin binding complicates standard mass-spectrometry screening, dedicated methods have been developed to identify the compound in human and equine samples (DOI; DOI).
Overall, the evidence base is limited and largely preclinical or early-phase; much of it dates to the mid-2000s, and CJC-1295 is not an approved therapeutic. The literature describes what was measured in defined experimental systems, not established outcomes in general use.
Why the Distinction Matters for Research Literacy
Understanding what CJC-1295 is means understanding that a single label spans two chemically different molecules with different expected kinetics. The DAC group is not a minor formulation detail — it is the structural element responsible for the extended-action profile that the primary studies report. Sourcing, characterization, and any interpretation of published data all depend on knowing which version a given source is actually describing. Reading the underlying papers, rather than secondary summaries, is the most reliable way to keep the two straight.
References
- Jetté L, et al. 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. Endocrinology. 2005;146(7):3052-8. https://doi.org/10.1210/en.2004-1286
- Teichman SL, et al. 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. J Clin Endocrinol Metab. 2005;91(3):799-805. https://doi.org/10.1210/jc.2005-1536
- Ionescu M, Frohman LA. Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog. J Clin Endocrinol Metab. 2006;91(12):4792-7. https://doi.org/10.1210/jc.2006-1702
- Alba M, et al. Once-daily administration of CJC-1295, a long-acting growth hormone-releasing hormone (GHRH) analog, normalizes growth in the GHRH knockout mouse. Am J Physiol Endocrinol Metab. 2006;291(6):E1290-4. https://doi.org/10.1152/ajpendo.00201.2006
- Sackmann-Sala L, et al. Activation of the GH/IGF-1 axis by CJC-1295, a long-acting GHRH analog, results in serum protein profile changes in normal adult subjects. Growth Horm IGF Res. 2009;19(6):471-7. https://doi.org/10.1016/j.ghir.2009.03.001
- Henninge J, et al. Identification of CJC-1295, a growth-hormone-releasing peptide, in an unknown pharmaceutical preparation. Drug Test Anal. 2010;2(11-12):647-50. https://doi.org/10.1002/dta.233
- Timms M, et al. An immuno polymerase chain reaction screen for the detection of CJC-1295 and other growth-hormone-releasing hormone analogs in equine plasma. Drug Test Anal. 2018;11(6):804-812. https://doi.org/10.1002/dta.2554
Research Use Only. The information above is provided solely for educational and scientific reference. CJC-1295 and related peptides described here are research compounds intended for laboratory research use only and are not drugs, dietary supplements, or products for human or animal consumption. Nothing on this page is medical advice, nor a recommendation to acquire, administer, or use any compound. Citations describe what investigators measured in controlled research settings and should not be read as established health outcomes.