CJC-1295 vs sermorelin
CJC-1295 and sermorelin are both GHRH(1-29) analogues that act at the GHRH receptor. This page compares the native-sequence sermorelin with the substituted, optionally albumin-binding CJC-1295, covering structure, stability, evidence, regulatory and WADA status, and identity testing.
Sermorelin is the first 29 residues of human growth hormone-releasing hormone (GHRH) with an amidated C-terminus, the shortest fragment that keeps full activity at the GHRH receptor. It was once an FDA-approved product (Geref) but has been discontinued in the US. CJC-1295 starts from the same 29-residue sequence and adds four amino acid substitutions designed to resist enzymatic breakdown.
The name CJC-1295 is used for two different molecules: CJC-1295 with DAC, which carries a reactive group that binds serum albumin, and the version without DAC, often called modified GRF(1-29). Comparing these with sermorelin shows how a natural peptide fragment can be progressively stabilized, and why precise naming matters for identity testing.
Side-by-side
| Attribute | CJC-1295 | Sermorelin |
|---|---|---|
| Origin | Synthetic analogue of GHRH(1-29) | Native human GHRH(1-29) sequence |
| Length | 29 residues; with DAC adds a modified C-terminal lysine | 29 residues |
| Modifications | D-Ala2, Gln8, Ala15, Leu27; with DAC: maleimidopropionyl-lysine linker | C-terminal amide only |
| Stability features | Substitutions reduce DPP-4 cleavage, deamidation and oxidation; DAC enables albumin conjugation | Rapidly cleaved by DPP-4; susceptible to Met oxidation and Asn deamidation |
| Receptor target | GHRH receptor | GHRH receptor |
| Evidence level | Early-clinical (early human pharmacokinetic studies of the DAC form) | Previously approved; historical clinical data |
| FDA / compounding | Not FDA-approved; check current compounding guidance | Previously approved as Geref, discontinued in the US; check current compounding guidance |
| WADA | Prohibited under S2 (GHRH analogues) | Prohibited under S2 (GHRH and its analogues) |
| Analytical pitfalls | Confirming DAC vs no-DAC form; masses differ substantially | Methionine oxidation; asparagine deamidation; DPP-4-type truncation products |
| Storage | Lyophilized at -20 °C, protected from light and moisture; avoid freeze-thaw | Lyophilized at -20 °C, protected from light and moisture; avoid freeze-thaw |
From native fragment to stabilized analogue
Sermorelin keeps the natural GHRH(1-29) sequence, so it is quickly inactivated in circulation, mainly by dipeptidyl peptidase-4 cutting between positions 2 and 3. CJC-1295 introduces D-alanine at position 2 to block that cleavage, glutamine at position 8 to reduce asparagine deamidation, alanine at position 15 to improve helical structure and leucine at position 27 in place of methionine to remove an oxidation site. These four changes are shared by both forms of CJC-1295 and distinguish them from sermorelin.
The role of DAC
The drug affinity complex (DAC) is a lysine bearing a maleimidopropionic acid group added at the C-terminus. The maleimide reacts with the free cysteine on serum albumin, forming a covalent conjugate that circulates much longer than the free peptide. Early human pharmacokinetic studies of CJC-1295 with DAC in healthy adults reported prolonged elevations of growth hormone and IGF-1, but clinical development did not lead to an approved product. Modified GRF(1-29), lacking DAC, has a short circulating time closer to that of sermorelin.
Identity testing for GHRH analogues
Because three related molecules share the same backbone, a certificate of analysis should state the exact sequence the mass was checked against: sermorelin, modified GRF(1-29) or CJC-1295 with DAC. The DAC form has a substantially higher mass due to the added lysine and linker, and its reactive maleimide can hydrolyze or form adducts during storage. For sermorelin, oxidized methionine and deamidated asparagine variants are the main degradation products to look for. See sermorelin vs tesamorelin for another GHRH analogue.
Frequently asked questions
What is the difference between CJC-1295 and sermorelin?
Sermorelin is the unmodified 29-residue N-terminal fragment of human GHRH. CJC-1295 is the same fragment with four amino acid substitutions that make it more resistant to breakdown, and in its DAC form it also carries a group that binds albumin. Both act at the GHRH receptor, but CJC-1295 persists much longer in circulation.
Is sermorelin FDA approved?
Sermorelin was previously approved by the FDA as Geref (sermorelin acetate), but that product has been discontinued in the US, so there is no currently marketed FDA-approved sermorelin. CJC-1295 has never been FDA-approved. Compounding status for both should be checked against current FDA guidance, and both are prohibited in sport under WADA class S2.
Is modified GRF(1-29) the same as CJC-1295?
Modified GRF(1-29) has the same four substitutions as CJC-1295 but lacks the DAC lysine-linker, so it does not bind albumin and is cleared quickly. It is often sold or described as CJC-1295 without DAC. The two molecules have different masses, so a certificate of analysis should name which form was tested.
Full entries
- 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.
- Sermorelin
Sermorelin is a synthetic peptide consisting of the first 29 amino acids of human growth hormone releasing hormone (GHRH). It was previously FDA-approved as Geref but has been discontinued in the US.
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