Ipamorelin vs CJC-1295: Two Different Doors to the Same Axis

Last updated August 13, 2026

Ipamorelin and CJC-1295 are searched together more often than almost any other pair in peptide research, and the reason is structural: they act on the same physiological axis through two different receptors. This page compares their mechanisms, their published characterisation and their regulatory position, strictly from a laboratory research perspective. Nothing here is medical advice, and the compounds discussed are research materials, not medicines.

What are ipamorelin and CJC-1295?

Ipamorelin is a synthetic pentapeptide of the growth hormone releasing peptide (GHRP) family. In the 1998 characterisation by Raun and colleagues it was described as the first selective GH secretagogue: in animal models it stimulated growth hormone release through the ghrelin receptor (GHS-R1a) without the ACTH, cortisol or prolactin elevations reported for earlier compounds of the family.

CJC-1295 is a modified analogue of growth hormone releasing hormone, GHRH(1-29), with amino-acid substitutions that resist enzymatic cleavage. It exists in two forms in the research literature and in our catalog: the base peptide, often called Mod GRF 1-29, and the DAC version with a drug affinity complex that binds albumin and extends the half-life dramatically. The differences between those two forms have their own dedicated comparison; this page treats the GHRH side as one family.

How do their mechanisms differ?

The two compounds are not competitors; they are two different doors into the same room. GHRH analogues like CJC-1295 act on the GHRH receptor of the pituitary, amplifying the amplitude of natural secretion pulses. GHRPs like ipamorelin act on the ghrelin receptor, a separate G-protein-coupled receptor, both initiating pulses and suppressing somatostatin, the axis brake. Because the receptors are distinct, the published literature treats the two classes as complementary tools rather than alternatives, and much of the preclinical work on the axis uses one compound of each class to dissect the two inputs separately.

Ipamorelin’s distinguishing property inside its own family is selectivity: the original characterisation reported no meaningful effect on ACTH, cortisol, prolactin, FSH, LH or TSH at doses that released growth hormone, which is what made it the clean pharmacological probe of the GHRP class.

What does the published evidence show?

The evidence bases are shaped very differently. Ipamorelin’s foundation is preclinical: the 1998 characterisation in animal models, followed by receptor pharmacology work across the GHRP family. Early clinical development for postoperative ileus was discontinued, so human data remain limited. CJC-1295 has published human pharmacokinetic and pharmacodynamic data: Teichman and colleagues reported in 2006 that single doses in healthy adults produced sustained, dose-dependent increases in growth hormone and IGF-1 lasting up to two weeks for the DAC form. Neither compound has approached the trial depth of the incretin class, and neither has any marketing authorisation.

Which research applications does each suit?

In laboratory models, ipamorelin is the reference probe for ghrelin-receptor pharmacology when selectivity matters, precisely because its off-target profile is the cleanest documented in its family. CJC-1295 is the tool for GHRH receptor studies where a degradation-resistant, long-acting ligand is needed, and the DAC and non-DAC forms let researchers separate receptor pharmacology from pharmacokinetics. Studies of the axis as a system frequently use both classes together, which is the honest reason the two names travel as a pair.

What is the regulatory status?

Neither compound is an authorised medicine anywhere; both are research materials only. In sport the position is explicit: the WADA Prohibited List names both classes in section S2, GHRH analogues with CJC-1295 cited as an example, and growth hormone releasing peptides with ipamorelin among the named examples. Both are prohibited at all times for athletes, and the live list is the binding reference.

Research sourcing and quality checks

Both compounds are available in our catalog as research reagents: ipamorelin, CJC-1295 without DAC and CJC-1295 with DAC. Where a batch has been tested, its report is published in the lab reports archive and linked from the product page. What a proper certificate should contain, and what it cannot prove, is covered in our guide on reading a certificate of analysis.

Conclusion

Ipamorelin versus CJC-1295 is not a versus at all: one opens the ghrelin-receptor door, the other the GHRH door, and the published literature treats them as complementary probes of the same axis. The meaningful differences are selectivity, where ipamorelin’s profile is the cleanest in its class, and evidence shape, where CJC-1295 carries the human pharmacokinetic data. For research procurement both remain unauthorised compounds, prohibited in sport, and documented batch by batch or not at all.

References

• Raun K et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol 1998. PubMed
• Teichman SL et al. Prolonged stimulation of growth hormone and IGF-1 secretion by CJC-1295, a long-acting analog of GHRH, in healthy adults. J Clin Endocrinol Metab 2006. PubMed
• WADA Prohibited List, section S2, current edition. wada-ama.org