Ipamorelin vs CJC-1295
Ipamorelin is a pentapeptide ghrelin receptor (GHS-R1a) agonist; CJC-1295 is a modified GHRH analogue, in some versions with an albumin-binding DAC group. This page compares their receptors, structures, research history and analytical considerations.
Ipamorelin and CJC-1295 both raise growth hormone release from the pituitary in experimental settings, but they act at different receptors. Ipamorelin is a synthetic growth hormone secretagogue that activates the ghrelin receptor, GHS-R1a. CJC-1295 is an analogue of growth hormone-releasing hormone (GHRH) that acts at the GHRH receptor.
The two are often discussed together because GHRH-receptor and ghrelin-receptor signaling are separate pathways that converge on GH release. Both reached early clinical testing and neither was approved. The name CJC-1295 also covers two distinct molecules, with and without the drug affinity complex (DAC), and this causes frequent confusion in catalogs and on certificates of analysis.
Side-by-side
| Attribute | Ipamorelin | CJC-1295 |
|---|---|---|
| Class | Growth hormone secretagogue (ghrelin mimetic) | GHRH analogue |
| Receptor | GHS-R1a (ghrelin receptor) | GHRH receptor |
| Length | 5 residues | 29-residue GHRH(1-29) backbone with four substitutions; DAC version carries an extra C-terminal lysine and linker |
| Structure | Contains non-proteinogenic and D-amino acids (Aib, D-2-naphthylalanine, D-Phe); C-terminal amide | Modified GHRH(1-29) amide; DAC version has a maleimide-based reactive group that binds albumin covalently |
| Selectivity | Reported in animal studies to raise GH with little effect on ACTH, cortisol or prolactin | Acts on the GHRH receptor; DAC version designed to extend circulation through albumin binding |
| Research history | Evaluated in early clinical studies, including for postoperative ileus; not approved | DAC version studied in early clinical trials in healthy adults; development discontinued |
| Evidence level | Early-clinical | Early-clinical |
| FDA status | Not approved by the FDA for any use | Not approved by the FDA for any use |
| WADA | Prohibited under S2 (GH secretagogues) | Prohibited under S2 (GHRH analogues) |
| Analytical pitfalls | D-amino acid and non-standard residue identity; diastereomer impurities | Confirming DAC vs no-DAC by mass; reactivity of the maleimide group; deamidation |
Two receptors, two pathways
Ipamorelin mimics ghrelin at GHS-R1a, a G protein-coupled receptor expressed in the pituitary and hypothalamus. CJC-1295 mimics GHRH at the GHRH receptor on pituitary somatotrophs. In physiology the two signals interact: GHRH stimulates GH synthesis and release, while ghrelin-receptor agonists amplify release and oppose somatostatin tone. Experimental work on combining the two classes reflects this convergence, but findings from animal and early human studies should not be generalized beyond the conditions tested.
DAC vs no-DAC
CJC-1295 with DAC carries a lysine and a maleimidopropionyl group at the C-terminus that reacts with a cysteine on serum albumin, forming a conjugate that circulates for much longer than the free peptide. The version without DAC, often called modified GRF(1-29), has the same four substitutions but no albumin-binding group, so it is cleared much faster. They are different molecules with different masses, and a certificate of analysis should name which one was tested.
Structural differences
Ipamorelin is a short peptide built from unusual residues, including aminoisobutyric acid and D-configured aromatic amino acids, which resist protease degradation. CJC-1295 keeps the 29-residue N-terminal fragment of GHRH, the minimum region needed for full receptor activity, with substitutions that improve resistance to dipeptidyl peptidase-4 cleavage and other degradation. Use the sequence analyzer to compare expected masses.
Frequently asked questions
What is the difference between ipamorelin and CJC-1295?
Ipamorelin is a pentapeptide agonist of the ghrelin receptor (GHS-R1a), while CJC-1295 is a 29-residue analogue of growth hormone-releasing hormone that acts at the GHRH receptor. Both increase GH release in experimental settings, but through separate receptor pathways. Neither is approved by the FDA.
What does DAC mean in CJC-1295?
DAC stands for drug affinity complex, a reactive maleimide-containing group attached through an added C-terminal lysine. It binds covalently to circulating albumin and greatly extends the peptide's presence in the bloodstream. CJC-1295 without DAC, also called modified GRF(1-29), lacks this group and is a different molecule with a different mass.
Are ipamorelin and CJC-1295 banned in sport?
Yes. WADA prohibits growth hormone secretagogues and GHRH analogues under section S2 of its Prohibited List, which covers ipamorelin and both forms of CJC-1295. Researchers working with athletes should check the current WADA Prohibited List for any changes.
Full entries
- Ipamorelin
Ipamorelin is a synthetic pentapeptide growth hormone secretagogue that acts as a selective agonist of the ghrelin receptor (GHS-R1a). It is investigational and not approved for any use.
- CJC-1295
CJC-1295 is a synthetic analogue of growth hormone releasing hormone (GHRH). The name properly refers to a version with a drug affinity complex (DAC) that binds albumin, but is also applied to modified GRF(1-29), which lacks DAC.
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