CJC-1295 and ipamorelin are two of the most widely discussed synthetic peptides in growth hormone research, and they are frequently mentioned together. They are not, however, the same kind of molecule. CJC-1295 is an analogue of growth hormone-releasing hormone (GHRH), while ipamorelin is a growth hormone-releasing peptide (GHRP) that acts at the ghrelin receptor. Understanding why researchers pair a GHRH analogue with a GHRP requires a short tour of hypothalamic-pituitary signalling, the history of each compound class and the structural choices that went into each molecule.
For laboratory research use only. Not for human or veterinary use. See our research use only policy.
This pillar guide covers both classes and links out to more detailed articles on CJC-1295 with DAC vs no DAC, ipamorelin structure and selectivity, tesamorelin as a stabilised GHRH analogue and kisspeptin-10 in reproductive-axis research.
At a glance: CJC-1295 no DAC
- Name: CJC-1295 no DAC
- Synonyms: Modified GRF (1-29), Mod GRF 1-29, tetrasubstituted GRF (1-29)
- Sequence: Tyr-D-Ala-Asp-Ala-Ile-Phe-Thr-Gln-Ser-Tyr-Arg-Lys-Val-Leu-Ala-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Leu-Ser-Arg-NH2
- Molecular formula: C152H252N44O42
- Molecular weight: 3367.9 g/mol
- CAS number: 863288-34-0
- Form: Lyophilised powder
- Purity: >99% (HPLC)
- Storage: 2-8°C, dark, upright, do not freeze. Keep sealed until use.
At a glance: ipamorelin
- Name: Ipamorelin
- Synonyms: NNC 26-0161
- Sequence: Aib-His-D-2-Nal-D-Phe-Lys-NH2
- Molecular formula: C38H49N9O5
- Molecular weight: 711.9 g/mol
- CAS number: 170851-70-4
- Form: Lyophilised powder
- Purity: >99% (HPLC)
- Storage: 2-8°C, dark, upright, do not freeze. Keep sealed until use.
At a glance: CJC-1295 no DAC and ipamorelin blend
- Name: CJC-1295 no DAC + ipamorelin
- Synonyms: Mod GRF 1-29 and ipamorelin blend
- Sequence: Not applicable (mixture of two peptides, see above)
- Molecular formula: Not applicable (mixture)
- Molecular weight: Not applicable (mixture)
- CAS number: Not applicable (mixture)
- Form: Lyophilised powder
- Purity: >99% (HPLC)
- Storage: 2-8°C, dark, upright, do not freeze. Keep sealed until use.
The growth hormone axis in brief
Growth hormone (GH, somatotropin) is synthesised and secreted by somatotroph cells of the anterior pituitary. Its release is governed mainly by two hypothalamic peptides with opposing actions. Growth hormone-releasing hormone, a 44-residue peptide, stimulates GH synthesis and release. Somatostatin, a 14- or 28-residue cyclic peptide, inhibits release. The interplay between the two produces the characteristic pulsatile pattern of GH secretion reported in mammals.
A third input was identified later. In 1996 Howard and colleagues cloned the growth hormone secretagogue receptor (GHS-R), the target of a group of synthetic peptides that had been known for over a decade to release GH. In 1999 Kojima and colleagues identified ghrelin, an acylated stomach peptide, as the endogenous ligand for this receptor. GHS-R1a is now commonly called the ghrelin receptor.
GH acts in turn on many tissues, in part by stimulating hepatic production of insulin-like growth factor 1 (IGF-1). GH and IGF-1 both feed back on the hypothalamus and pituitary. Research tools that act at the GHRH receptor or the ghrelin receptor are therefore useful for probing different points in this system.
Two receptors, two pathways
The GHRH receptor is a class B G protein-coupled receptor that signals mainly through Gs, raising intracellular cyclic AMP and activating protein kinase A. GHS-R1a is a class A G protein-coupled receptor that signals predominantly through Gq/11, activating phospholipase C and raising intracellular calcium. Because the two pathways are distinct and converge on the same cell type, research has examined how they interact. Bowers and others reported in the 1990s that combined exposure to GHRH and a GHRP produced a GH response greater than the sum of each alone in several models, a phenomenon usually described as synergy.
Part one: CJC-1295 and GHRH analogues
Native GHRH and its limitations
Human GHRH was isolated and sequenced in 1982 by the groups of Guillemin and of Rivier and Vale, from pancreatic tumours associated with acromegaly. Researchers found that the first 29 residues, GHRH(1-29)-NH2, retained the activity of the full peptide at the receptor. This shorter fragment, known as sermorelin, became a template for later analogues.
GHRH(1-29) has a very short half-life in plasma. The main route of inactivation is cleavage by dipeptidyl peptidase-4 between Ala2 and Asp3, supplemented by other proteases and by oxidation of Met27. Most GHRH analogue programmes were designed to address one or more of these weaknesses.
Modified GRF (1-29): CJC-1295 no DAC
Modified GRF (1-29) introduces four substitutions to the native fragment: D-alanine at position 2 to hinder DPP-4 cleavage, glutamine at position 8 to reduce deamidation, alanine at position 15 to favour helix stability and leucine at position 27 to remove the oxidation-prone methionine. These changes are visible in the sequence in the identity section above. The peptide remains a 29-residue C-terminal amide.
CJC-1295 with DAC
The code CJC-1295 was originally assigned by the Canadian company ConjuChem to a molecule that adds a lysine bearing a maleimidopropionyl group to the same tetrasubstituted backbone. This Drug Affinity Complex (DAC) was designed to bind covalently to the cysteine-34 residue of serum albumin, protecting the peptide from clearance. Jetté and colleagues described the approach in rats in 2005, and Teichman and colleagues reported in 2006 an estimated half-life of roughly six to eight days in adult volunteers. CJC-1295 with DAC did not progress to approval.
In the research supply market, "CJC-1295 no DAC" became shorthand for the tetrasubstituted backbone without the albumin-binding group, which is why one code now refers to two molecules. Our dedicated article on CJC-1295 with DAC vs no DAC sets out the differences in detail.
Other GHRH analogues
CJC-1295 is not the only approach to stabilising GHRH. Tesamorelin keeps the full 44-residue human sequence and adds an N-terminal trans-3-hexenoyl group, which blocks DPP-4 recognition. A tesamorelin product was approved by the US Food and Drug Administration in 2010 for a specific indication in adults living with HIV, a regulatory fact that does not apply to research-grade material. Our article on tesamorelin as a stabilised GHRH analogue compares these strategies.
Part two: ipamorelin and the GHRP class
Origins of the GHRPs
Growth hormone-releasing peptides emerged from work by Cyril Bowers and colleagues in the late 1970s and early 1980s on small enkephalin-derived peptides. GHRP-6, a hexapeptide reported in 1984, was one of the first well-characterised members. GHRP-1, GHRP-2 and hexarelin followed. These peptides released GH in vitro and in vivo but acted at a receptor that was not then identified. Non-peptide secretagogues such as MK-677 (ibutamoren) were later developed against the same target.
A limitation reported for the early GHRPs was a lack of selectivity. In various studies GHRP-6 and GHRP-2 were associated with increases in ACTH, cortisol and prolactin alongside GH, which complicates interpretation when the aim is to study the GH axis in isolation.
Ipamorelin's structure
Ipamorelin was developed at Novo Nordisk from the GHRP-1 structure. It is a pentapeptide amide, Aib-His-D-2-Nal-D-Phe-Lys-NH2, combining the conformationally constrained amino acid Aib, two aromatic D-amino acids and a C-terminal lysine amide. These non-standard residues give it greater resistance to proteolysis than an equivalent all-L peptide. At 711.9 g/mol it is less than a quarter of the mass of CJC-1295 no DAC.
The 1998 selectivity study
Raun and colleagues introduced ipamorelin in the European Journal of Endocrinology in 1998. Working with rat pituitary cells and with rat and swine models, they reported GH release comparable to GHRP-6 without significant increases in ACTH or cortisol, even at concentrations well above those giving a maximal GH response. They described it as the first selective growth hormone secretagogue. The original findings came from animal and in vitro systems and should be read in that context. Our article on ipamorelin structure and selectivity covers this in more depth.
Clinical history
Ipamorelin was later investigated in a phase 2 clinical study in postoperative ileus, published by Beck and colleagues in 2014, which did not report a significant difference from placebo on its primary endpoint. It has not been approved as a medicine.
Why the two classes are studied together
The rationale for examining GHRH analogues and GHRPs together rests on three observations reported in the literature. First, the two act at separate receptors with distinct second-messenger pathways. Second, GHRPs have been reported to act partly at the hypothalamic level, including effects on GHRH neurones and on somatostatin tone, in addition to their direct pituitary action. Third, experimental studies from the 1990s onward reported synergistic GH release when both receptors were engaged.
For researchers, this makes the combination of a GHRH receptor agonist and a selective GHS-R1a agonist a useful model for probing receptor cross-talk, somatotroph responsiveness and the role of somatostatin. Pairing a short-acting GHRH analogue with a short-acting GHRP also preserves an episodic signalling pattern, whereas an albumin-bound GHRH analogue produces sustained receptor exposure. Which pattern is appropriate depends entirely on the experimental question.
A note on pre-blended material
Some laboratories prefer to purchase each peptide separately to control the ratio between them and to analyse each component independently. Others choose a pre-blended vial for convenience. A blend has no single CAS number, formula or molecular weight, and characterisation by HPLC will show two principal peaks rather than one. Our guide on how to read a peptide certificate of analysis explains how chromatograms and mass spectra are interpreted.
Related hypothalamic-pituitary signalling peptides
The GH axis is one of several hypothalamic-pituitary systems studied with synthetic peptide tools. The reproductive axis is governed by gonadotropin-releasing hormone, which is itself regulated by kisspeptin acting at the KISS1R receptor. Our article on kisspeptin-10 and the KISS1 gene covers that system, from the gene's discovery in melanoma research to the 2003 genetic studies linking its receptor to puberty. Readers interested in GH-derived fragments may also find our article on the AOD-9604 hGH fragment relevant.
Quality, identity and storage
All three listings in this cluster are supplied as lyophilised powders at >99% purity by HPLC. Identity is typically confirmed by mass spectrometry, where the observed mass is compared against the theoretical molecular weight given in the identity sections above. For a general explanation of purity figures and testing, see our research peptides UK buyer's guide.
We recommend storing each product at 2-8°C, in the dark, upright and not frozen, keeping vials sealed until use. Both peptides contain residues that can degrade with exposure to moisture, light and air over time. General practice for dry peptide material is set out in our article on how to store lyophilised peptides.
Regulatory position
Neither CJC-1295 (with or without DAC) nor ipamorelin holds a marketing authorisation as a medicine in the UK or elsewhere. Compound Cave supplies them strictly as laboratory reagents for in vitro and research use, and they are not presented or intended for any human or veterinary use. For background on how UK law applies to research peptides, see are peptides legal in the UK.
Summary
CJC-1295 no DAC is a stabilised 29-residue GHRH analogue acting at the GHRH receptor. Ipamorelin is a selective pentapeptide GHRP acting at the ghrelin receptor. They differ in structure, size, receptor and signalling pathway, and they are studied together because those pathways converge on the pituitary somatotroph. Careful attention to naming, particularly the DAC distinction, and to identity data is essential when designing or reading research involving either compound.
View CJC-1295 no DAC in the catalogue, ipamorelin in the catalogue or the CJC-1295 no DAC and ipamorelin blend in the catalogue.
Frequently asked questions
What is the difference between CJC-1295 and ipamorelin?
CJC-1295 is an analogue of growth hormone-releasing hormone and acts at the GHRH receptor. Ipamorelin is a growth hormone-releasing peptide that acts at the growth hormone secretagogue receptor (GHS-R1a), also called the ghrelin receptor. They are structurally unrelated and use different signalling pathways.
Why are CJC-1295 and ipamorelin discussed together?
Because they act on the same pituitary cell type through separate receptors, research since the 1990s has examined how GHRH and GHRP signalling interact. Studies reported that the two classes acted synergistically on growth hormone release in some experimental models.
Is the CJC-1295 in the catalogue the DAC or no DAC version?
Compound Cave lists CJC-1295 no DAC, also known as modified GRF (1-29). It does not carry the albumin-binding Drug Affinity Complex. Our article on CJC-1295 with DAC vs no DAC explains the difference.
What is in the CJC-1295 no DAC and ipamorelin vial?
It is a pre-blended lyophilised powder containing both CJC-1295 no DAC and ipamorelin. Because it is a mixture, it has no single CAS number, molecular formula or molecular weight. Identity data for each component is given in this article.
Are CJC-1295 or ipamorelin approved medicines?
No. CJC-1295 with DAC and ipamorelin were each investigated in clinical studies, but neither has received a marketing authorisation. Compound Cave supplies these materials only for laboratory research.
How should these peptides be stored?
We recommend storing the lyophilised powders at 2-8°C, in the dark, upright and not frozen, with vials kept sealed until use.
References
- 1. Guillemin R, Brazeau P, Böhlen P, et al. Growth hormone-releasing factor from a human pancreatic tumor that caused acromegaly. Science. 1982;218:585-587.
- 2. Rivier J, Spiess J, Thorner M, Vale W. Characterization of a growth hormone-releasing factor from a human pancreatic islet tumour. Nature. 1982;300:276-278.
- 3. Bowers CY, Momany FA, Reynolds GA, Hong A. On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone. Endocrinology. 1984;114:1537-1545.
- 4. Howard AD, Feighner SD, Cully DF, et al. A receptor in pituitary and hypothalamus that functions in growth hormone release. Science. 1996;273:974-977.
- 5. Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139:552-561.
- 6. Kojima M, Hosoda H, Date Y, et al. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature. 1999;402:656-660.
- 7. 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;146:3052-3058.
- 8. Teichman SL, Neale A, Lawrence B, 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;91:799-805.
- 9. Beck DE, Sweeney WB, McCarter MD; Ipamorelin 201 Study Group. Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. Int J Colorectal Dis. 2014;29:1527-1534.
For laboratory research use only. Not for human or veterinary use. See our research use only policy.