Ipamorelin vs CJC-1295: Two Peptides, Two Receptors
Ipamorelin and CJC-1295 are catalogued side by side and sold together in a blend, which makes them look like variations of one thing. They are not. Ipamorelin is a five-residue synthetic agonist of the ghrelin receptor; CJC-1295 is a modified 29-residue analog of growth hormone-releasing hormone that acts at a different receptor. This post compares their origins, structures, receptor literature and lab characterization.
Research blog: general laboratory-science and literature context. Not medical advice. Sealed Peptides materials are for laboratory research use only, and are not for human or veterinary use.
Two receptors, two hormone systems
Ipamorelin was described in 1998 as a selective growth hormone secretagogue [1]. It acts at the growth hormone secretagogue receptor, GHS-R1a, which was identified in 1996 [2] and later shown to be the receptor for the stomach hormone ghrelin [3]. Reviews of secretagogue development place it among synthetic ghrelin mimetics [4].
CJC-1295 is built on the first 29 residues of growth hormone-releasing hormone (GHRH), the fragment that carries receptor activity at the GHRH receptor, a different receptor on the same pituitary cell type [5]. Early work on GRF(1-29) conjugates showed that attaching a reactive group allowed albumin binding and continued receptor activation [6].
Structure and size at a glance
- Ipamorelin: Aib-His-D-2Nal-D-Phe-Lys-NH2, formula C38H49N9O5, listed molecular weight 711.9 Da. A C-amidated pentapeptide with non-coded residues.
- CJC-1295 without DAC: a modified GHRH(1-29) amide with four amino acid substitutions and no added group; also called modified GRF(1-29).
- CJC-1295 with DAC: the same backbone plus a lysine-linked maleimide "drug affinity complex" that binds albumin; listed molecular weight 3647.1 Da.
- Scale: the DAC form is about five times heavier than ipamorelin, so the two behave very differently on HPLC and in mass spectra.
What "DAC" changes
The DAC group is the reason two different molecules are sold as CJC-1295. In the original pharmacokinetic characterization the albumin-binding form showed a half-life measured in days, far longer than unmodified GHRH analogs [7]. Ipamorelin has no such feature. The CJC-1295 with vs without DAC post explains how to tell which form a label describes.
Why they appear together
Because the two peptides act at separate receptors, papers treat them as distinct pathways, and catalogs offer a pre-mixed CJC-1295 / Ipamorelin blend that contains two separate compounds. Note that this blend uses CJC-1295 without DAC. For a comparison with the other GHRH-derived peptide, see Ipamorelin vs Sermorelin.
Checking each one in the lab
Identity for both is a Mass spectrometry check against the expected mass. Ipamorelin usually appears as one or two simple ions near m/z 712 ([M+H]+); the larger CJC-1295 forms show several charge states. Purity is HPLC area percent. Because ipamorelin contains D-residues and an unnatural naphthylalanine, its retention does not follow the usual hydrophobicity predictions, so compare against a reference run rather than a calculated value.
The sequence notation guide explains how to read entries like Aib and D-2Nal when comparing labels.
Handling notes
Both are supplied as Lyophilized powders and stored sealed and frozen. For solution arithmetic with each listed molecular weight, see the Ipamorelin calculator and the molarity calculator. Both are sold for laboratory research use only.
Terms used in this guide
Related tools and guides
References
- Raun K, Hansen BS, Johansen NL, Thøgersen H, Madsen K, Ankersen M, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-61. PMID 9849822 · DOI
- Howard AD, Feighner SD, Cully DF, Arena JP, Liberator PA, Rosenblum CI, et al. A receptor in pituitary and hypothalamus that functions in growth hormone release. Science. 1996;273(5277):974-7. PMID 8688086 · DOI
- Kojima M, Hosoda H, Date Y, Nakazato M, Matsuo H, Kangawa K. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature. 1999;402(6762):656-60. PMID 10604470 · DOI
- Smith RG. Development of growth hormone secretagogues. Endocr Rev. 2005;26(3):346-60. PMID 15814848 · DOI
- Halmos G, Szabo Z, Dobos N, Juhasz E, Schally AV. Growth hormone-releasing hormone receptor (GHRH-R) and its signaling. Rev Endocr Metab Disord. 2025;26(3):343-352. PMID 39934495 · DOI
- Jetté L, Léger R, Thibaudeau K, Benquet C, Robitaille M, Pellerin I, 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. PMID 15817669 · DOI
- 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. PMID 16352683 · DOI
Cited literature is provided for scientific context only. Many of these reviews concern proteins or pharmaceutical development; they are cited for general chemistry and do not describe or endorse any use of these products.
For laboratory research use only. Not for human or veterinary use. This post is general chemistry and literature context and does not describe or endorse any use of Sealed Peptides products.
