What Is CJC-1295?
CJC-1295 is a synthetic analogue of Growth Hormone Releasing Hormone (GHRH) — the hypothalamic peptide that stimulates pituitary somatotrophs to release growth hormone (GH). Native GHRH is a 44-amino acid peptide with a short plasma half-life of 7–10 minutes, rapidly cleaved by dipeptidyl peptidase IV (DPP-IV) at the Ala²-Asp³ bond.
CJC-1295 incorporates two key modifications over native GHRH(1-29): a substitution of Ala² with D-Ala² (DPP-IV resistance) and the addition of a Drug Affinity Complex (DAC) — a reactive Lys-maleimide linker at the C-terminus that forms a covalent thioether bond with cysteine-34 on circulating serum albumin. This albumin-binding dramatically extends the half-life from minutes to approximately 6–8 days in animal studies, enabling sustained GHRH receptor stimulation from a single administration.
Molecular weight: ~3,367 Da. CJC-1295 acts exclusively on the GHRH receptor (GHRH-R) on pituitary somatotrophs, increasing both the amount of GH released per pulse and basal GH secretion in GH-deficient animal models.
What Is Ipamorelin?
Ipamorelin (Aib-His-D-2-Nal-D-Phe-Lys-NH₂) is a synthetic pentapeptide designed as a selective agonist of the ghrelin receptor (GHSR-1a) — also called the GH secretagogue receptor. It was first described by Novo Nordisk researchers in 1998 as a novel GH secretagogue with an exceptionally selective pharmacological profile.
Unlike earlier GH releasing peptides (GHRP-2, GHRP-6), Ipamorelin produces GH release with minimal stimulation of cortisol, prolactin, or ACTH in animal models. This selectivity is attributed to its specific binding geometry at the GHSR-1a, which activates the GH-releasing pathway without simultaneously engaging cortisol or prolactin secretion pathways that earlier GHRPs activated.
Molecular weight: 711.86 Da. Ipamorelin acts at a different receptor than CJC-1295 — GHSR-1a vs. GHRH-R — and through a different cellular mechanism, making it mechanistically complementary rather than redundant.
Synergistic Stack Research
The CJC-1295 + Ipamorelin combination is studied based on a well-founded mechanistic rationale: the two peptides act on different GH-releasing pathways with complementary effects.
- CJC-1295 (GHRH-R agonist): Increases the amplitude of GH pulses — more GH released per pulse from pituitary somatotrophs. The DAC modification provides sustained, baseline GHRH receptor stimulation.
- Ipamorelin (GHSR-1a agonist): Increases the frequency of GH pulses — triggers additional GH release events. Also potentiates GHRH-stimulated GH release at the pituitary level through a separate intracellular pathway.
The combination therefore simultaneously addresses both pulse amplitude and pulse frequency — the two primary parameters of physiological GH secretion. Animal studies comparing the combination to monotherapy with either compound consistently report greater total GH output and IGF-1 elevation with the combination than with either agent alone.
GH Pulse Amplification in Animal Models
The landmark pharmacokinetic and pharmacodynamic study of CJC-1295 DAC in rats (Jetté et al., published in Journal of Clinical Endocrinology & Metabolism, 2005) demonstrated:
- A single dose of CJC-1295 DAC produced a sustained elevation of plasma GH lasting over 6 days in rats — consistent with the albumin-binding half-life extension mechanism.
- Plasma IGF-1 levels were elevated by 1.5- to 3-fold above baseline, persisting for the duration of the observation period.
- The GH response was dose-dependent within the studied range of 25–150 µg/kg, with no evidence of desensitisation (pituitary depletion) in the 8-day study window.
When Ipamorelin is added to CJC-1295 protocols in rodent studies, acute GH pulses are superimposed on the sustained baseline elevation produced by CJC-1295, resulting in both a higher GH trough and higher GH peak values compared to either compound alone. This "dual wave" GH pattern more closely resembles physiological youthful GH secretion than either agent produces individually.
Comparison with Other GH Secretagogues
| Compound | Receptor | Route | Half-life | Selectivity | Line |
|---|---|---|---|---|---|
| CJC-1295 (DAC) | GHRH-R | Parenteral | ~6–8 days | High — GH only | APEX |
| Ipamorelin | GHSR-1a | Parenteral | ~2 hours | Very high — GH only, no cortisol/prolactin | APEX |
| GHRP-6 | GHSR-1a | Parenteral | ~1–2 hours | Low — elevates cortisol, prolactin, ACTH | — |
| MK-677 (Ibutamoren) | GHSR-1a | Oral | ~24 hours | Moderate — some cortisol elevation in studies | — |
| Sermorelin | GHRH-R | Parenteral | ~10–20 min | High — GH only; short duration limits utility | — |
Dosing Ranges in Published Studies
The following dose ranges are drawn from published animal studies and are provided for reference in research protocol design only:
CJC-1295 (with DAC)
- Rat studies: 25–150 µg/kg per injection, weekly frequency
- Observed effects: Sustained GH/IGF-1 elevation for 6–8 days post-dose
- Pituitary desensitisation: Not observed within 8-day study window at these doses
Ipamorelin
- Rat studies: 1–300 µg/kg per injection, acute or pulsatile protocols
- Peak GH response: Typically at 15–30 min post-injection in rodents
- Cortisol/ACTH: No significant elevation observed up to 300 µg/kg in rat studies
Combination Protocols (Animal Studies)
- CJC-1295 weekly + Ipamorelin acute pulsatile dosing is the most commonly studied combination design
- Concurrent administration may potentiate acute GH pulses above CJC-1295 baseline in rat models
Frequently Asked Questions
- What is CJC-1295?
- CJC-1295 is a synthetic GHRH analogue with a Drug Affinity Complex (DAC) modification that enables albumin binding and extends plasma half-life to approximately 6–8 days in animal studies. It stimulates GH release via the GHRH receptor on pituitary somatotrophs. Sold For Research Use Only.
- What is Ipamorelin and how does it differ from GHRP-6?
- Ipamorelin is a selective ghrelin receptor (GHSR-1a) agonist that stimulates GH release without significantly elevating cortisol, prolactin, or ACTH — unlike GHRP-6, which produces significant non-GH hormonal side effects in animal models. This selectivity makes Ipamorelin a cleaner tool for GH pulse research.
- Why are CJC-1295 and Ipamorelin studied together?
- They act on different receptors (GHRH-R vs GHSR-1a) with complementary effects: CJC-1295 increases GH pulse amplitude; Ipamorelin increases GH pulse frequency. Animal studies show the combination produces greater GH and IGF-1 output than either compound alone, and more closely resembles physiological GH secretion patterns.
- How does CJC-1295 compare to MK-677?
- CJC-1295 is a peptide requiring parenteral administration; MK-677 is an orally active non-peptide GHSR-1a agonist. MK-677 provides continuous GH/IGF-1 elevation (~24h half-life), while CJC-1295 + Ipamorelin produces a more physiologically pulsatile GH pattern. The research context determines which profile is more appropriate.
CJC-1295 / Ipamorelin Blend — Research Grade
HPLC-verified >98% purity. Batch-specific Certificate of Analysis included. Lyophilised powder for maximum stability. Ships in temperature-controlled packaging.
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