What Is Sermorelin?
Sermorelin (GHRH 1-29 NH₂) is the biologically active N-terminal fragment of endogenous growth hormone-releasing hormone (GHRH). With 29 of the 44 amino acids found in full-length GHRH, it retains complete biological activity at the pituitary GHRH receptor (GHRHR). It was the first GHRH analogue approved by the FDA (as Geref) for the diagnosis and treatment of GH deficiency in children, withdrawn from the US market in 2008 for commercial rather than safety reasons.
Mechanism of Action
Sermorelin binds GHRHR on anterior pituitary somatotrophs, stimulating the synthesis and pulsatile release of endogenous growth hormone. Crucially, it works within the physiological feedback loop — elevated GH and IGF-1 levels provide negative feedback, preventing supraphysiological GH excursion. This self-regulating property distinguishes it from direct GH administration.
Research Findings
- GH axis restoration: In GH-deficient adults, Sermorelin restores pulsatile GH secretion patterns towards those of younger subjects
- Lean body mass: Studies show increases in lean body mass and reductions in fat mass over 3–6 month research periods
- Sleep quality: Sermorelin increases slow-wave (deep) sleep, during which the majority of endogenous GH is naturally secreted
- Bone mineral density: Research in GH-deficient adults shows improvements in lumbar spine BMD
- Safety: Long-term studies confirm a favourable safety profile with no evidence of tumourigenesis or pituitary desensitisation
Stacking Research
Sermorelin is frequently studied in combination with GHRP-6 or Ipamorelin — the GHRH analogue amplifies the pituitary response to GHRP stimulation.
Related compounds: CJC-1295 (no DAC), Ipamorelin, GHRP-6.