Overview

Sermorelin is the synthetic amidated 29-amino-acid fragment of native growth-hormone-releasing hormone (GHRH), corresponding to the shortest sequence that retains full GHRH-receptor activity. It was originally developed and marketed as Geref for use in the diagnosis and management of paediatric growth-hormone deficiency and later as an adjunct in adult growth-hormone-axis research.

Because sermorelin acts at the endogenous GHRH receptor rather than substituting for growth hormone itself, its effect is contingent on functional somatotroph reserve and preserves the pulsatile character of the endogenous GH release pattern — a feature emphasised across the research literature.

Mechanism (as reported in the literature)

  • GHRH-receptor agonism. Sermorelin binds the pituitary GHRH receptor and triggers pulsatile GH release similar to endogenous GHRH stimulation.
  • Preserved feedback. Research characterises sermorelin as leaving GH negative-feedback loops intact, so the risk of the sustained supraphysiological GH concentrations seen with exogenous GH administration is reported as lower.
  • Short plasma half-life. Sermorelin has a plasma half-life of roughly 10–15 minutes in most reported studies, resulting in narrow pulses of GH release that are typically administered at bedtime to align with the natural nighttime GH pulse.

Research findings

  • Paediatric GH-deficiency work. The original Geref clinical programme demonstrated growth-velocity improvements in appropriately selected paediatric populations.
  • Adult growth-hormone-axis studies. Small trials in older adults reported modest increases in IGF-1 and improvements in body-composition measures over 16–24-week intervals (Vittone et al., 1997; Corpas et al., 1992; PMID 1740455).
  • Somatostatin-tone dependence. Research indicates the GH response to sermorelin is influenced by prevailing somatostatin tone, which underlies the nighttime-administration convention.

Common dosing (from published research protocols)

Reference research protocols report 100–300 mcg subcutaneously, once daily at bedtime. Some GH-secretagogue-adjunct protocols pair sermorelin with a ghrelin-mimetic such as ipamorelin at the same administration.

Reconstitution

A 5 mg vial reconstituted with 2 mL of bacteriostatic water yields a 2,500 mcg/mL solution.

  • 100 mcg = 0.04 mL = 4 units on a U-100 syringe
  • 200 mcg = 0.08 mL = 8 units
  • 300 mcg = 0.12 mL = 12 units

Storage

Reconstituted sermorelin is refrigerated at 2–8 °C and reported as stable for approximately 14–30 days.

  • CJC-1295 DAC — the long-acting, albumin-binding GHRH analog.
  • Ipamorelin — the reference selective GH-secretagogue, commonly paired with sermorelin.
  • Hexarelin — a related GH-secretagogue with additional cardiovascular pharmacology.

Common stacks

References

  • Corpas, E., et al. (1992). “Growth hormone-releasing hormone-(1-29) twice daily reverses the decreased GH and insulin-like growth factor-I levels in old men.” Journal of Clinical Endocrinology & Metabolism, 75(2). PMID 1740455.
  • Vittone, J., et al. (1997). “Effects of single nightly injections of growth hormone-releasing hormone (GHRH 1-29) in healthy elderly men.” Metabolism, 46(1). PMID 9005974.
  • Walker, R. F. (2006). “Sermorelin: a better approach to management of adult-onset growth hormone insufficiency?” Clinical Interventions in Aging, 1(4). PMID 18046911.