What Is CJC-1295? GHRH Analogue With and Without DAC

CJC-1295 is a synthetic analogue of growth hormone-releasing hormone (GHRH) built on the hormone’s first 29 amino acids, the shortest fragment with full activity. The name covers two distinct molecules. CJC-1295 with DAC carries a reactive group that binds albumin after administration and has a half-life of about a week. CJC-1295 without DAC, also called modified GRF(1-29), is short-acting. Most human data come from the DAC version.

For laboratory research use only. The compounds discussed are not approved for human or veterinary use and are not drugs, foods or cosmetics. This article summarises published research and is not medical advice.

Key points

Based on GHRH(1-29)-NH₂ with four amino acid substitutions that resist enzymatic breakdown.
With DAC: albumin-binding, half-life 5.8–8.1 days in healthy adults.
Without DAC (Mod GRF 1-29): ~3368 g/mol, short-acting.
Raised GH and IGF-I in healthy adults while preserving pulsatile GH secretion.
Prohibited in sport; LC-MS/MS detection methods exist.

The two forms

	CJC-1295 without DAC (Mod GRF 1-29)	CJC-1295 with DAC
Core sequence	GHRH(1-29)-NH₂ with substitutions at positions 2, 8, 15 and 27
Extra group	None	Lysine with a maleimide-containing linker (DAC) at the C-terminus
Molecular weight	~3367.9 g/mol	~3647.2 g/mol (PubChem CID 91971820)
Mechanism of prolongation	Protease resistance only	Covalent binding to albumin after administration
Half-life	Short (minutes to tens of minutes)	5.8–8.1 days (Teichman et al., 2006)

Our CJC-1295 (no DAC) is supplied in 5 mg and 10 mg vials; a separate CJC-1295 with DAC product is also listed. The full comparison is in CJC-1295 with DAC vs without DAC.

Why GHRH needed modifying

Native GHRH is a 44-residue hypothalamic peptide that acts on GHRH receptors on pituitary somatotrophs, a G-protein-coupled receptor that signals mainly through cAMP (Halmos et al., 2025). The 1–29 fragment retains full activity, and in its amidated form it is the drug sermorelin (3357.9 g/mol). However, it is rapidly degraded, notably by dipeptidyl peptidase-4 cleavage after residue 2. The four substitutions in CJC-1295 (D-alanine at position 2, glutamine at 8, alanine at 15 and leucine at 27) protect cleavage-prone sites and an oxidation-prone methionine.

Position	Native GHRH(1-29)	CJC-1295	Rationale
2	Ala	D-Ala	Resists DPP-4 cleavage
8	Asn	Gln	Reduces deamidation
15	Gly	Ala	Stabilises helix
27	Met	Leu	Removes oxidation site

Human studies of CJC-1295 with DAC

Two randomised, placebo-controlled ascending-dose trials in healthy adults aged 21–61 found that a single subcutaneous dose raised mean plasma GH 2- to 10-fold for 6 days or more and IGF-I 1.5- to 3-fold for 9–11 days. The estimated half-life was 5.8–8.1 days. After multiple doses, IGF-I remained above baseline for up to 28 days, and no serious adverse reactions were reported (Teichman et al., 2006).

A follow-up study in healthy men sampled GH every 20 minutes overnight before and one week after a single dose. GH pulsatility was preserved, with unchanged pulse frequency and magnitude, but trough GH rose 7.5-fold, mean GH 46% and IGF-I 45% (Ionescu et al., 2006). The authors concluded that elevated baseline GH, rather than larger pulses, drove the IGF-I increase.

Detection

GHRH and its analogues are prohibited by the World Anti-Doping Agency. A King’s College London study characterised 19 in vitro metabolites of sermorelin, tesamorelin, CJC-1295 and CJC-1295 with DAC, and developed an LC-MS/MS method with detection limits generally at or below 1 ng/mL (Memdouh et al., 2021).

Handling in the lab

Store lyophilized powder at −20 °C, sealed and dark.
Water-soluble; reconstitute with bacteriostatic or sterile water and swirl gently (method).
Confirm which form you have by MS: the ~280 Da difference between no-DAC and DAC versions is unambiguous.
Calculate concentrations with the peptide reconstitution calculator.

Open questions

How does the short-acting no-DAC form behave pharmacokinetically in humans? Published human data focus on the DAC version.
Does continuous GHRH receptor stimulation by the DAC version cause receptor desensitisation over longer periods?

Related research

Frequently asked questions

What is CJC-1295?

CJC-1295 is a synthetic analogue of growth hormone-releasing hormone (GHRH) based on its first 29 amino acids. The name is used for two different compounds: the version with a ‘drug affinity complex’ (DAC) that binds albumin, and the version without DAC, also known as modified GRF(1-29).

What does CJC-1295 do in research?

It activates the GHRH receptor on pituitary somatotrophs, stimulating growth hormone (GH) release. In healthy adults, a single dose of the DAC version raised mean GH 2- to 10-fold for 6 days or more and IGF-I 1.5- to 3-fold for 9–11 days.

What is the half-life of CJC-1295?

For CJC-1295 with DAC, the estimated half-life in healthy adults was 5.8–8.1 days. The version without DAC is much shorter-acting, closer to native GHRH fragments, which last minutes.

Is CJC-1295 the same as Mod GRF 1-29?

CJC-1295 without DAC is the same peptide sometimes sold as ‘Mod GRF 1-29’ (tetrasubstituted GRF 1-29). CJC-1295 with DAC is a different, albumin-binding molecule.

Does CJC-1295 abolish natural GH pulses?

No. In a study of healthy men, GH pulsatility was preserved after CJC-1295 with DAC; trough (basal) GH rose 7.5-fold while pulse frequency and size were unchanged.

References

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. 2006. PMID: 16352683 https://pubmed.ncbi.nlm.nih.gov/16352683/
Ionescu M, et al. 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. PMID: 17018654 https://pubmed.ncbi.nlm.nih.gov/17018654/
Memdouh S, et al. Advances in the detection of growth hormone releasing hormone synthetic analogs. Drug Test Anal. 2021. PMID: 34665524 https://pubmed.ncbi.nlm.nih.gov/34665524/
Halmos G, et al. Growth hormone-releasing hormone receptor (GHRH-R) and its signaling. Rev Endocr Metab Disord. 2025. PMID: 39934495 https://pubmed.ncbi.nlm.nih.gov/39934495/
PubChem Compound Summary for CID 91971820, CJC-1295. National Center for Biotechnology Information. https://pubchem.ncbi.nlm.nih.gov/compound/91971820
PubChem Compound Summary for CID 16132413, Sermorelin. National Center for Biotechnology Information. https://pubchem.ncbi.nlm.nih.gov/compound/16132413