Sermorelin vs CJC-1295: GHRH-Analog Research Compared

Background

Growth hormone-releasing hormone (GHRH) is a 44-amino-acid hypothalamic peptide that binds GHRH receptors on pituitary somatotrophs to drive growth hormone (GH) pulsatile secretion. The first 29 amino acids retain full biological activity — a fact that underpins the entire class of synthetic GHRH analogs used in research.

Both sermorelin and CJC-1295 are GHRH(1-29) analogs, but their medicinal chemistry and resulting pharmacokinetics differ substantially. This is why they're used for different experimental questions.

Sermorelin (GHRH 1-29)

Sermorelin is the unmodified GHRH(1-29) sequence with no stabilizing substitutions. Key properties:

• Molecular weight: ~3,358 Da
• Plasma half-life: ~10–20 minutes (rapid DPP-4 cleavage at position 2)
• Pharmacodynamics: drives a sharp, physiological GH pulse; clears quickly

This short action makes sermorelin useful for researchers studying acute GH pulse dynamics, pituitary responsiveness time-courses, and hypothalamic-pituitary axis integrity. It is the closest pharmacological analog to endogenous GHRH in half-life and pulse shape.

CJC-1295 (no DAC)

CJC-1295 without DAC — sometimes called modified GRF(1-29) or MOD GRF 1-29 — is GHRH(1-29) with four amino-acid substitutions (Aib-2, Ala-8, Lys-30 (actually Gln-substitution), plus others depending on lineage) that confer DPP-4 resistance and serum stability:

• Molecular weight: ~3,367 Da
• Plasma half-life: ~30 minutes (vs sermorelin's ~10–20 min)
• Pharmacodynamics: similar peak GH release but somewhat extended exposure

Research using no-DAC CJC-1295 typically addresses questions about GHRH receptor engagement kinetics with a more consistent molecule than native GHRH, while preserving pulsatile pharmacodynamics.

CJC-1295 with DAC

CJC-1295 with Drug Affinity Complex (DAC) adds a maleimidopropionic acid linker that covalently binds serum albumin, producing:

• Plasma half-life: 6–8 days (vs 30 min for no-DAC)
• Pharmacodynamics: sustained elevation of GH and IGF-1 with loss of pulsatility

See /blog/cjc-1295-dac-vs-no-dac-research-design for a dedicated DAC comparison.

Side-by-side comparison

| Property | Sermorelin | CJC-1295 (no DAC) | CJC-1295 with DAC |

|---|---|---|---|

| Sequence | Native GHRH(1-29) | Modified GRF(1-29), 4 substitutions | Modified GRF(1-29) + DAC linker |

| MW | ~3,358 Da | ~3,367 Da | ~3,647 Da |

| Half-life | 10–20 min | ~30 min | 6–8 days |

| GH pulse | Physiological | Physiological | Abolished (sustained) |

| Best for | Acute pulse studies | Standard GHRH reference | Sustained GH/IGF-1 exposure |

What laboratories typically study

• Pituitary function — GH release assays in cultured somatotrophs, GHRH receptor binding and activation
• Axis integrity — hypothalamic-pituitary GH axis function tests in animal models
• Comparative pharmacology — GHRH-class kinetics vs ghrelin-receptor secretagogue (GHRP) class
• Combination studies — GHRH analog + GHRP for synergistic GH release (see /blog/cjc-1295-ipamorelin-mechanism)
• IGF-1 kinetics — time courses of downstream IGF-1 elevation

Handling and quality

• Both supplied as lyophilized powder (typical format 5 mg)
• Store lyophilized at -20°C, light-protected
• Reconstitute with sterile/bacteriostatic water
• Reconstituted solution stable ~4 weeks at 2–8°C
• Verify by HPLC (≥99.0%) with MS identity; obtain batch-specific COA

Related reading

• /research/sermorelin — sermorelin compound profile
• /research/cjc-1295-no-dac — CJC-1295 no-DAC compound profile
• /compare/ipamorelin-vs-sermorelin — GHRH vs GHRP comparison
• /compare/cjc-1295-dac-vs-no-dac — DAC variant comparison
• /blog/cjc-1295-dac-vs-no-dac-research-design — half-life deep dive
• /blog/ghrp-6-ghrp-2-ipamorelin-growth-hormone-secretagogue-research — ghrelin-receptor class
• /category/muscle-growth-research — broader category

RUO disclaimer

For laboratory research use only. Not for human consumption. Consult the literature and institutional oversight (IACUC or equivalent) for study design.