The Three Compounds: Mechanisms and Receptors
CJC-1295 — Long-Acting GHRH Analogue (SOMA Line)
CJC-1295 (also known as DAC:GRF) is a synthetic 30-amino-acid peptide analogue of GHRH with a Drug Affinity Complex (DAC) moiety that binds covalently to albumin after injection, extending its half-life from minutes to 6–8 days. It binds to the GHRH receptor (GHRHR) on pituitary somatotrophs, stimulating GH synthesis and release. Published rodent studies show sustained elevation of plasma GH and IGF-1 levels over 2 weeks following a single injection. CAS: 863288-34-0 · M.W.: 3367.97 g/mol · Available in 2 mg vials.
Ipamorelin — Selective GHRP (SOMA Line)
Ipamorelin is a synthetic pentapeptide GH secretagogue receptor (GHSR-1a) agonist — a member of the GHRP class. It is the most selective GHRP, producing GH release with minimal stimulation of cortisol, prolactin, or ACTH — a key differentiator from earlier GHRPs like GHRP-6 and GHRP-2. Its half-life is approximately 2 hours, producing discrete GH pulses rather than sustained elevation. CAS: 170851-70-4 · M.W.: 711.85 g/mol · Available in 5 mg vials.
Sermorelin — Endogenous GHRH Fragment (SOMA Line)
Sermorelin is the first 29 amino acids of endogenous GHRH (GHRH 1-29), representing the biologically active fragment required for GHRHR binding. It has the shortest half-life of the three (~10–20 minutes) and produces the most physiological GH release pattern — preserving the natural pulsatile rhythm of the hypothalamic-pituitary axis. It was FDA-approved (as Geref) for GH deficiency diagnosis and treatment in children. CAS: 86168-78-7 · M.W.: 3358.01 g/mol · Available in 5 mg vials.
Side-by-Side Comparison: CJC-1295 vs Ipamorelin vs Sermorelin
| Property | CJC-1295 | Ipamorelin | Sermorelin |
|---|---|---|---|
| Class | GHRH analogue (DAC) | GHRP (ghrelin mimic) | GHRH fragment |
| Receptor target | GHRHR | GHSR-1a (ghrelin) | GHRHR |
| Half-life | 6–8 days | ~2 hours | 10–20 minutes |
| GH pulse profile | Sustained elevation | Discrete pulses | Physiological pulsatile |
| Cortisol stimulation | Minimal | Minimal (selective) | Minimal |
| Prolactin stimulation | Minimal | None (key advantage) | Minimal |
| IGF-1 elevation | Sustained (high) | Moderate (pulsatile) | Moderate (brief) |
| Research dosing | 1–2x weekly | Daily / multiple daily | Daily |
| Combination use | Paired with Ipamorelin | Paired with CJC-1295 | Paired with GHRP |
| Purity at RP | ≥98% HPLC | ≥98% HPLC | ≥98% HPLC |
| Format | 2 mg vial | 5 mg vial | 5 mg vial |
Combination Protocols in Research
The most common GH secretagogue protocol in published rodent research combines a GHRH analogue with a GHRP. The rationale: GHRH analogues amplify GH synthesis at the pituitary; GHRPs trigger immediate GH release via the ghrelin receptor. Used together, they produce synergistic GH pulse amplification exceeding either compound alone — typically 3–5x the GH release of either alone in rodent models.
Most studied combination: CJC-1295 + Ipamorelin — combining the long half-life of CJC-1295 with the clean selectivity profile of Ipamorelin. This is the most commonly referenced GH research protocol in 2025. Rainbow Peptide supplies both: CJC-1295 2 mg and Ipamorelin 5 mg.
Other GH Secretagogues Worth Noting
The SOMA line also includes GHRP-2 (more potent GH release, some cortisol stimulation), GHRP-6 (appetite-stimulating GHRP with strong GH release), and Hexarelin (the most potent GHRP for GH release, with cardiovascular research applications).
Frequently Asked Questions
What is the main difference between CJC-1295 and Ipamorelin?
CJC-1295 binds to the GHRH receptor and has a 6–8 day half-life due to DAC albumin binding, producing sustained GH and IGF-1 elevation. Ipamorelin binds to the ghrelin receptor (GHSR-1a) and has a 2-hour half-life, producing discrete GH pulses. They are complementary — most research protocols combine both for synergistic GH amplification.
Is Sermorelin better than CJC-1295 for research?
Neither is objectively "better" — they serve different research designs. Sermorelin's short half-life makes it appropriate for studies requiring physiological pulsatility and close mimicry of endogenous GHRH. CJC-1295's extended half-life makes it appropriate for studies requiring sustained GH/IGF-1 elevation with less frequent dosing. Sermorelin also has human clinical data given its prior FDA approval.
Why is Ipamorelin preferred over GHRP-6 in research?
Ipamorelin is highly selective for GH release, with minimal stimulation of cortisol, prolactin, or ACTH — side effects seen with GHRP-6 and GHRP-2. For studies isolating GH-axis effects, Ipamorelin's selectivity produces cleaner data. GHRP-6 is preferred when appetite stimulation or broader GHSR-1a pharmacology is the research target.
Summary
CJC-1295 is a long-acting GHRH analogue (6–8 day half-life) studied for sustained GH and IGF-1 elevation. Ipamorelin is a selective GHRP (2-hour half-life) with a clean hormonal profile. Sermorelin is the endogenous GHRH 1-29 fragment with the most physiological GH release pattern. All three are available from Rainbow Peptide in ≥98% purity HPLC-verified formulations. For Research Use Only.
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