CJC-1295 and Ipamorelin: Receptor Pharmacology Compared
How a GHRH-receptor agonist and a ghrelin-receptor agonist differ — receptor targets, half-life variants, selectivity, and the endpoints used in published GH-axis research.
CJC-1295 and Ipamorelin are two growth-hormone (GH) secretagogues that act on two different receptors in the pituitary gland. This article compares their receptor pharmacology, their selectivity, and the endpoints that published GH-axis research measures.
It is a literature overview and does not describe human use.
Two different receptor targets
CJC-1295 — the GHRH pathway
CJC-1295 is a modified analog of growth-hormone-releasing hormone (GHRH). It binds the GHRH receptor on pituitary somatotroph cells and increases the amplitude of GH pulses.
Two variants exist:
- CJC-1295 without DAC (also called modified GRF 1-29) — a short half-life of about 30 minutes.
- CJC-1295 with DAC (Drug Affinity Complex) — binds to serum albumin, which extends the half-life to several days.
The two variants produce very different GH profiles. The no-DAC variant produces short, pulse-like signals. The DAC variant produces sustained elevation.
Ipamorelin — the ghrelin pathway
Ipamorelin is a selective agonist of the ghrelin receptor (GHS-R1a). This pathway can trigger GH pulses independently of GHRH, so it adds to pulse frequency and initiation.
Ipamorelin is more selective than earlier ghrelin mimetics such as GHRP-6 and Hexarelin. In published studies, it caused little change in cortisol, prolactin, or appetite. For this reason, researchers use it to study GH-mediated effects with fewer stress-axis confounders. See Ipamorelin vs GHRP-6 for the selectivity comparison.
How the two receptor pathways differ
| Property | CJC-1295 | Ipamorelin |
|---|---|---|
| Receptor | GHRH receptor | Ghrelin receptor (GHS-R1a) |
| Effect on GH pulses | Increases pulse amplitude | Increases pulse initiation |
| Half-life | About 30 minutes (no DAC); several days (DAC) | Short |
| Selectivity | Acts on the GHRH receptor | Little change in cortisol or prolactin in published studies |
The two receptors regulate GH release through separate signaling pathways. Physiology studies of the somatotropic axis have examined how these pathways interact. Those studies describe receptor biology. They do not establish any human use.
Endpoints used in published research
Studies of GH secretagogues typically measure:
- Serum IGF-1 — the main downstream marker of GH exposure; it changes slowly.
- GH pulse characteristics — frequent blood sampling to measure pulse amplitude and frequency.
- Body composition — for example DEXA measurements of lean mass and fat mass.
- Glucose and insulin — GH elevation can reduce insulin sensitivity.
- Sleep architecture — slow-wave sleep correlates with endogenous GH release.
Considerations when comparing studies
- 1Variant selection. The DAC and no-DAC variants are not interchangeable. Sustained GHRH-receptor stimulation from the DAC variant changes the pulse pattern that the study measures.
- 2Selectivity. Less selective ghrelin mimetics (GHRP-6, Hexarelin) also raise cortisol and prolactin. They can confound studies that isolate GH-mediated effects.
- 3Receptor desensitization. Continuous ghrelin-receptor stimulation can reduce the response over time. Study length is therefore a design variable.
Related reading
For the mechanism comparison, see CJC-1295 vs Ipamorelin. For glossary entries, see CJC-1295 and Ipamorelin. For the class background, see the GH secretagogue research guide.
Research reagents
Both compounds are available as 5 mg lyophilized research reagents with a batch Certificate of Analysis:
- CJC-1295 (no DAC) 5 mg — Supreme Biologics, FourNines Research, Wolf Biotech
- Ipamorelin 5 mg — Supreme Biologics, FourNines Research, Wolf Biotech
All products mentioned are chemical reagents for laboratory research only. Not for human or veterinary use. This article summarizes published research literature and is not medical advice.
