By the Peptide Insider Research Desk · 12 min read · Last updated: September 13, 2026
CJC-1295 is a tetrasubstituted analogue of growth hormone-releasing hormone fragment 1–29 (GHRH(1-29)) carrying a C-terminal lysine linked to a maleimidopropionic acid group, the "Drug Affinity Complex" (DAC) that lets the peptide bind covalently to circulating albumin [1,2]. The same 29-residue backbone without that reactive group is catalogued as Modified GRF 1-29, and the two preparations circulate in research catalogues under a dense set of labels — cjc-1295 no dac, cjc no dac, cjc with dac, cjc 1295 w dac, cjc without dac, cjc1295 dac and their blend variants with ipamorelin [1,3]. This review is a companion to the site's single-compound CJC-1295, sermorelin and ipamorelin reviews. It reconstructs the GHRH analogue family as a modification ladder — native GHRH(1-44), the 1–29 fragment (sermorelin), the degradation-resistant tetrasubstituted fragment (Mod GRF 1-29) and the albumin-conjugated fragment (CJC-1295) — explains what the DAC group does chemically, and documents the catalogue notations, misspellings and blend labels that refer to each rung. All content is provided strictly for research reference.
Definition box. "DAC" (Drug Affinity Complex) is a C-terminal Lys(Nε-3-maleimidopropionamide) extension that reacts with the free thiol of cysteine-34 on serum albumin, forming a stable thioether bond [2,4]. cjc1295 with dac (CJC-1295 proper) carries this group and was reported to have an elimination half-life of roughly 6–8 days in healthy adults [1]. cjc1295 no dac (Modified GRF 1-29, also written cjc 1295 without dac or cjc without dac in some listings) is the identical tetrasubstituted GHRH(1-29) sequence without the extension, and behaves like other short-lived GHRH fragments [1,5]. Sermorelin is the unmodified GHRH(1-29)-NH2; the strings semorelin, sermorlin, semorlin, sermoreline and sermorellin are phonetic misspellings of the same compound [6]. Research use only; not for human or veterinary use.
Introduction
The native hormone exists as 44- and 40-residue forms; the first 29 residues carry full receptor-activating capacity and became the reference fragment, sermorelin, in 1980s diagnostic and pediatric work [6,7]. A 1995 PNAS study introduced amino-acid substitutions that protected the fragment from plasma proteases [8], and a 2005 Endocrinology paper from ConjuChem appended an albumin-reactive group to that stabilised fragment, generating CJC-1295 [2]. Because the intermediate (substituted but unconjugated) peptide was never given an INN, catalogues improvised: "Mod GRF 1-29", "CJC-1295 without DAC" and "cjc no dac" all name the same molecule, while sermorelin peptides, peptides sermorelin and peptide sermorelin name the unsubstituted parent [3,6].
Two further layers sit on top. GHRH analogues are often co-listed or pre-blended with ipamorelin, a pentapeptide acting at a different receptor (GHS-R1a), so strings such as cjc 1295 ipamorelin peptide, cjc 1295 ipamorelin no dac and cjc-1295 ipamorelin no dac describe a two-receptor pairing rather than one compound [9,10]. Catalogues also contract ipamorelin to "ipa" (ipa peptide, ipa peptides) or misspell it as ipamorlin [3]. This article gives each rung its chemistry and maps every notation onto it.
Biological background: the GHRH–GHRHR axis
GHRH from arcuate-nucleus neurons acts on the GHRH receptor (GHRHR), a class B G-protein-coupled receptor on pituitary somatotrophs. A 2.6 Å cryo-EM structure showed the peptide as a single α-helix whose N-terminus inserts into the transmembrane core, with Tyr1 and Asp3 forming the activating contacts [11]. Activation couples to Gs, raises cAMP and drives pulsatile growth hormone (GH) release and, downstream, hepatic insulin-like growth factor I (IGF-I) [7,11].
GHRH is inactivated within minutes in plasma: dipeptidyl peptidase IV (DPP-IV) removes the N-terminal Tyr-Ala dipeptide to give inactive GHRH(3-44), and trypsin-like enzymes cleave at internal basic residues [5]. Every analogue in the family answers this instability — by substituting cleavage-prone residues, acylating the N-terminus (tesamorelin) or tethering the peptide to a long-lived carrier (CJC-1295) [2,8,12].
Structure and mechanism: the modification ladder
Rung 1 — GHRH(1-29)-NH2 (sermorelin)
Sermorelin is the C-terminally amidated 29-residue fragment Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-NH2, supplied as the acetate salt (hence the catalogue string sermorelin acetate peptide) [6]. A 1999 BioDrugs review summarised its diagnostic and pediatric use; it is a full GHRHR agonist with a plasma half-life of minutes, since residues 2, 8, 15 and 27 remain vulnerable to DPP-IV cleavage, deamidation and oxidation [5,6]. The answer to the frequent question is sermorelin a peptide is therefore unambiguous: it is a 29-amino-acid peptide of approximately 3,358 g/mol [6].
Rung 2 — tetrasubstituted GRF(1-29) (Modified GRF 1-29; "CJC-1295 without DAC")
Izdebski and co-workers replaced protease- and oxidation-sensitive residues in GHRH(1-29) and reported analogues with higher potency and stability [8]. The variant that entered research catalogues carries four substitutions — D-Ala2 (blocks DPP-IV), Gln8 (replaces deamidation-prone Asn), Ala15 (replaces Gly, stabilising the helix) and Leu27 (replaces oxidation-prone Met) [2,8]. Jetté and colleagues used exactly this sequence as the peptide portion of their albumin bioconjugates; the unconjugated tetrasubstituted peptide is what suppliers list as cjc 1295 without dac, cjc-1295 no dac or cjc1295 no dac [2]. Its half-life remains in the minutes-to-tens-of-minutes range reported for unconjugated GHRH fragments [2,5].
Rung 3 — CJC-1295 (tetrasubstituted GRF(1-29)-Lys(MPA)-NH2; "CJC-1295 with DAC")
CJC-1295 adds a thirtieth residue, lysine, whose side-chain amine carries a 3-maleimidopropionyl group. The maleimide undergoes Michael addition with albumin's single free thiol (Cys34), forming a covalent thioether in vivo [2,4]. Because albumin circulates for about 19 days and escapes renal filtration, the conjugate inherits an extended residence time: Teichman and colleagues reported an estimated half-life of 5.8–8.1 days in healthy adults, with mean GH elevated for six days or more and IGF-I for 9–11 days after a single administration in the trial setting [1]. Ionescu and Frohman further showed that GH secretion remained pulsatile during this continuous stimulation, with trough GH raised roughly 7.5-fold while pulse frequency and amplitude were unchanged [13]. In GHRH-knockout mice, daily CJC-1295 normalised growth and body composition, whereas 48- or 72-hour intervals were less effective [14]. A proteomic follow-up in eleven healthy men identified serum protein changes (apolipoprotein A1 and transthyretin isoforms, β-haemoglobin and albumin fragments) one week after exposure, proposed as GH/IGF-I axis biomarkers [15].
Tesamorelin, an N-terminally hexenoylated GHRH(1-44), stabilises by a different route and is reviewed in the site's tesamorelin article [12].
| Compound | Backbone | Stabilising modification | Reported half-life | Catalogue labels |
|---|---|---|---|---|
| Sermorelin | GHRH(1-29)-NH2 | None (acetate salt) | Minutes [5,6] | sermorelin acetate; semorelin, sermorlin (misspellings) |
| Modified GRF 1-29 | [D-Ala2,Gln8,Ala15,Leu27]GHRH(1-29)-NH2 | Four substitutions [8] | Minutes to tens of minutes [2] | cjc no dac; cjc-1295 no dac; cjc without dac |
| CJC-1295 | Mod GRF(1-29)-Lys30(MPA)-NH2 | Substitutions + albumin-reactive DAC [2] | 5.8–8.1 days [1] | cjc with dac; cjc 1295 w dac; cjc1295 dac |
| Tesamorelin | GHRH(1-44)-NH2 | N-terminal trans-3-hexenoyl [12] | Approximately 26–38 min [12] | tesamorelin; TH9507 |
| Ipamorelin (partner, not a GHRH analogue) | Aib-His-D-2-Nal-D-Phe-Lys-NH2 | Non-natural residues [9] | Short-acting; minutes to hours [9,10] | ipa peptide; ipamorlin; ipamorelin 10mg |
Nomenclature and catalogue variants
The table below interprets the strings most often encountered in supplier catalogues, research forums and search logs. Interpretations are the authors' reading of catalogue convention, not manufacturer definitions. Vial-size strings are catalogue attributes only and carry no protocol meaning.
| String as encountered | Type | Interpretation |
|---|---|---|
| cjc-1295 no dac · cjc no dac · cjc1295 no dac · cjc 1295 without dac · cjc without dac | Absence label | Modified GRF 1-29 — the tetrasubstituted GHRH(1-29) fragment without the Lys(MPA) extension [2,8] |
| cjc with dac · cjc 1295 w dac · cjc w dac · cjc1295 dac · cjc1295 with dac | Presence label | CJC-1295 proper, carrying the maleimidopropionyl-lysine albumin-binding group [1,2] |
| research peptide dac 5mg | Catalogue attribute | A 5 mg lyophilised vial of a DAC-bearing peptide, almost always CJC-1295; the mass refers to vial content, not a protocol |
| cjc 1295 ipamorelin peptide · cjc 1295 ipamorelin no dac · cjc-1295 ipamorelin no dac | Blend label | A co-lyophilised or co-listed pairing of Mod GRF 1-29 (or CJC-1295) with ipamorelin; two receptors, two compounds [9,10] |
| sermorelin-ipamorelin-cjc1295 | Triple-blend label | Three-component listing; sermorelin and Mod GRF/CJC-1295 are both GHRHR agonists, so the triple is chemically redundant at one receptor [6,9] |
| semorelin · sermorlin · semorlin · sermoreline · sermorellin | Phonetic misspelling | Sermorelin, GHRH(1-29)-NH2 [6] |
| sermorelin peptides · peptides sermorelin · peptide sermorelin · sermorelin acetate peptide | Suffix/prefix variant | Sermorelin; "acetate" denotes the counter-ion of the supplied salt [6] |
| sermorelin 5mg | Catalogue attribute | Vial content of 5 mg sermorelin acetate; not a protocol |
| ipa peptide · ipa peptides · peptide ipamorelin · ipamorlin | Contraction / misspelling | Ipamorelin, the GHS-R1a-selective pentapeptide [9] |
| ipamorelin 10mg | Catalogue attribute | Vial content of 10 mg ipamorelin; not a protocol |
Evidence by domain
| Domain | Compound | Model | Key reported finding | Ref. |
|---|---|---|---|---|
| Pharmacokinetics | CJC-1295 | Healthy adults (two RCTs) | Half-life 5.8–8.1 d; GH raised 2–10-fold for ≥6 d; IGF-I 1.5–3-fold for 9–11 d | [1] |
| Pulsatility | CJC-1295 | Healthy men | Trough GH ↑ ~7.5-fold; pulse frequency/amplitude unchanged | [13] |
| Growth (preclinical) | CJC-1295 | GHRH-knockout mouse | Daily exposure normalised growth and body composition | [14] |
| Biomarkers | CJC-1295 | 11 healthy men | Five serum protein spots changed at one week | [15] |
| Receptor pharmacology | GHRH / analogues | Cryo-EM | N-terminal Tyr1/Asp3 contacts define activation | [11] |
| Stability | Tetrasubstituted GRF | In vitro / rat | Substituted analogues resist DPP-IV and show higher potency | [8] |
| Diagnostic use | Sermorelin | Pediatric GHD | Rapid, relatively specific provocative test; fewer false positives | [6] |
| Partner selectivity | Ipamorelin | Rat pituitary; rat, swine | GH release comparable to GHRP-6 with no ACTH/cortisol rise | [9] |
Pharmacokinetics and the albumin-tethering hypothesis
The DAC platform's central claim is that albumin tethering converts a minutes-long peptide into a days-long one without changing receptor pharmacology; rat pituitary activation [2] and the human trials [1] support this. Whether a tethered 66 kDa carrier alters access to the transmembrane pocket described by Zhou and colleagues has not been directly studied [11].
The two-receptor rationale for CJC/ipamorelin blends
Ipamorelin, described by Raun and colleagues in 1998 as "the first selective growth hormone secretagogue", acts at GHS-R1a and — unlike GHRP-6 and GHRP-2 — did not raise ACTH or cortisol in rat and swine models [9]. GHRH and GHS-R1a agonists act synergistically on somatotrophs in the classical secretagogue literature [10]. Blends labelled cjc 1295 ipamorelin no dac invoke this rationale, but no peer-reviewed study of the specific co-formulation has been identified; the evidence remains component-wise, as discussed in the site's tesamorelin/ipamorelin blend review.
Limitations of the evidence
- Discontinued programme. CJC-1295's clinical development stopped in phase 2; the human dataset consists of small early-phase trials from a single sponsor [1,13,15].
- No head-to-head DAC vs no-DAC comparison. The "with" and "without" preparations have not been compared in the same study; half-life differences are inferred across separate literatures [1,2,5].
- Catalogue identity is unverified. A vial labelled "cjc no dac" is chemically Mod GRF 1-29 only if the four substitutions are present; mass confirmation (about 3,368 g/mol for Mod GRF 1-29 versus about 3,647 g/mol for CJC-1295) is the only way to tell [2,8].
- Blend labels have no combination data. Every CJC/ipamorelin or sermorelin/ipamorelin/CJC-1295 listing rests on component-wise evidence [9,10].
Where to source for research
CJC-1295 (with DAC), Modified GRF 1-29 (labelled "no DAC"), sermorelin acetate and ipamorelin are listed by several research-chemical suppliers as lyophilised powders in vials described by milligram content and by the notations catalogued above. Because the DAC and no-DAC forms differ by a single residue and are frequently mislabelled, researchers evaluating suppliers should request a lot-specific certificate of analysis with HPLC purity and mass-spectrometric confirmation. Current research-grade availability includes Short Chain Aminos, BioPep, Catalyst Research and Apex Research Services. Our supplier evaluation guide and supplier reviews outline the documentation researchers can reasonably expect. All listings are for laboratory research use only.
Frequently asked questions
What does "no DAC" mean on a CJC-1295 label?
"No DAC" means the peptide lacks the C-terminal lysine-maleimidopropionamide group that lets CJC-1295 bind covalently to albumin. The product is chemically Modified GRF 1-29 — the same tetrasubstituted GHRH(1-29) sequence — and shares the short plasma half-life of other unconjugated GHRH fragments rather than the multi-day half-life reported for CJC-1295 [1,2].
What is cjc 1295 ipamorelin?
"cjc 1295 ipamorelin" is a catalogue label for a two-compound pairing: a GHRH(1-29) analogue (CJC-1295 with DAC or, more often, Mod GRF 1-29 "no DAC") plus ipamorelin, a GHS-R1a-selective pentapeptide. The two act at different pituitary receptors; the pairing rationale rests on classical GHRH–secretagogue synergy, not on published studies of the specific blend [9,10].
Is sermorelin a peptide?
Yes. Sermorelin is the 29-residue amidated N-terminal fragment of human GHRH, GHRH(1-29)-NH2, about 3,358 g/mol, supplied as the acetate salt. It is the unmodified parent of Mod GRF 1-29 and CJC-1295 [6].
Are semorelin, sermorlin and sermoreline different compounds?
No. "semorelin", "sermorlin", "semorlin", "sermoreline" and "sermorellin" are phonetic misspellings of sermorelin that appear in catalogue listings and search logs. They all denote GHRH(1-29)-NH2. Researchers should confirm identity by sequence and mass on the certificate of analysis rather than by label spelling [6].
How does the DAC group extend half-life?
The maleimide on the DAC group reacts with the free thiol of albumin's cysteine-34 to form a stable thioether bond. The peptide then circulates attached to albumin, a 66 kDa protein with a half-life of about 19 days that escapes renal filtration. Teichman and colleagues reported a resulting CJC-1295 half-life of 5.8–8.1 days in healthy adults [1,4].
What is "ipa peptide"?
"ipa peptide" (also "ipa peptides", "ipamorlin") is a catalogue contraction for ipamorelin, the pentapeptide Aib-His-D-2-Nal-D-Phe-Lys-NH2 reported by Raun and colleagues in 1998 as a GH secretagogue that did not raise ACTH or cortisol in rat and swine models. It is not a GHRH analogue and acts at GHS-R1a [9].
Does CJC-1295 abolish pulsatile GH secretion?
Not in the reported human data. Ionescu and Frohman found that GH secretion remained pulsatile during continuous CJC-1295 stimulation, with pulse frequency and amplitude unchanged; trough GH rose about 7.5-fold and this, rather than larger pulses, accounted for the IGF-I increase [13].
Works Cited
- Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA. 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;91(3):799–805. doi:10.1210/jc.2005-1536. PMID 16352683.
- Jetté L, Léger R, Thibaudeau K, 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):3052–3058. doi:10.1210/en.2004-1286. Publisher record.
- Sinha DK, Balasubramanian A, Tatem AJ, et al. Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males. Transl Androl Urol. 2020;9(Suppl 2):S149–S159. doi:10.21037/tau.2019.11.30. PMID 32257855.
- Kratz F. Albumin as a drug carrier: design of prodrugs, drug conjugates and nanoparticles. J Control Release. 2008;132(3):171–183. doi:10.1016/j.jconrel.2008.05.010. PMID 18582981.
- Frohman LA, Downs TR, Heimer EP, Felix AM. Dipeptidylpeptidase IV and trypsin-like enzymatic degradation of human growth hormone-releasing hormone in plasma. J Clin Invest. 1989;83(5):1533–1540. doi:10.1172/JCI114049. Publisher record.
- Prakash A, Goa KL. Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency. BioDrugs. 1999;12(2):139–157. doi:10.2165/00063030-199912020-00007. PMID 18031173.
- Frohman LA, Jansson JO. Growth hormone-releasing hormone. Endocr Rev. 1986;7(3):223–253. doi:10.1210/edrv-7-3-223.
- Izdebski J, Pinski J, Horvath JE, Halmos G, Groot K, Schally AV. Synthesis and biological evaluation of superactive agonists of growth hormone-releasing hormone. Proc Natl Acad Sci U S A. 1995;92(11):4872–4876. doi:10.1073/pnas.92.11.4872. Publisher record.
- Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552–561. doi:10.1530/eje.0.1390552. PMID 9849822.
- Bowers CY. Growth hormone-releasing peptide (GHRP). Cell Mol Life Sci. 1998;54(12):1316–1329. doi:10.1007/s000180050257.
- Zhou F, Zhang H, Cong Z, et al. Structural basis for activation of the growth hormone-releasing hormone receptor. Nat Commun. 2020;11:5205. doi:10.1038/s41467-020-18945-0. PMID 33060564.
- Falutz J, Allas S, Blot K, et al. Metabolic effects of a growth hormone-releasing factor in patients with HIV. N Engl J Med. 2007;357(23):2359–2370. doi:10.1056/NEJMoa072375. PMID 18057338.
- 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):4792–4797. doi:10.1210/jc.2006-1702. PMID 17018654.
- Alba M, Fintini D, Sagazio A, 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–E1294. doi:10.1152/ajpendo.00201.2006. PMID 16822960.
- Sackmann-Sala L, Ding J, Frohman LA, Kopchick JJ. 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):471–477. doi:10.1016/j.ghir.2009.03.001. PMID 19386527.
All content strictly for research reference. CJC-1295, Modified GRF 1-29, sermorelin and ipamorelin are research compounds in this context; they are not for human or veterinary use, and nothing in this article constitutes guidance on handling, administration or protocols. Related reviews: CJC-1295 single-compound review · Sermorelin (GHRH 1–29) · Ipamorelin · Tesamorelin / ipamorelin blend · GHRP-6.