Sermorelin: A Synthetic GHRH Peptide
Sermorelin is the synthetic form of the N-terminal 29-amino-acid fragment of human growth hormone-releasing hormone — the shortest GHRH sequence that retains full biological activity 01. The molecule has a measured molecular weight of 3,357.9 Da and binds the GHRH receptor on anterior pituitary somatotrophs, where it activates the Gs-alpha / adenylyl cyclase / cAMP cascade and triggers pulsatile release of endogenous growth hormone 0207. Because Sermorelin works upstream through the pituitary, GH release remains subject to negative feedback by somatostatin and circulating IGF-1 — the pulse is amplified, not overridden.
That distinction matters. Sermorelin is not growth hormone. It is a Sermorelin mechanism of action that uses the body's own secretory machinery, which is why the published pediatric trials of the late 1980s and 1990s read more like endocrine restoration than hormone replacement. The first major pediatric trial — Thorner and the international multi-site study group, 1996 — administered 30 mcg/kg subcutaneously at bedtime to 110 prepubertal children with idiopathic GH deficiency and reported a significant increase in height velocity, with about 74% of children responding within six months 03. Kirk and colleagues had reported a sustained 12-month growth-velocity acceleration in idiopathic short stature two years earlier 04.
What the Published Sermorelin Literature Has Measured
Across a body of work that begins with the 1984 GHRH-analog clinical pharmacology of Grossman and colleagues 08 and reaches the modern GH-secretagogue reviews of Ishida and co-authors 1112, the Sermorelin record covers four registers.
First, mechanism. GHRH-receptor activation on somatotrophs raises intracellular cAMP, drives GH gene transcription and vesicular release, and induces hepatic IGF-1 downstream 0107. The pulsatile rhythm is preserved because somatostatin tone is preserved.
Second, pharmacokinetics. Frohman and colleagues measured a plasma half-life of approximately 11-12 minutes after IV or subcutaneous dosing in adult men, with clearance around 2.4-2.8 L/min and rapid N-terminal proteolytic degradation 05. The Ishida review notes that the GH-secretory pharmacodynamic effect persists 2-4 hours after a single subcutaneous injection — far longer than plasma presence would predict 12.
Third, pediatric clinical efficacy. The Thorner 1996 cohort remains the cornerstone trial 03, supported by the Kirk 1994 idiopathic-short-stature cohort 04 and the Prakash and Goa 1999 review of Sermorelin as both a diagnostic provocative test (1 mcg/kg IV) and a treatment for idiopathic pediatric GHD 06.
Fourth, adult research. The Khorram 1997 study administered 10 mcg/kg subcutaneously nightly for 16 weeks to nineteen men and women aged 55-71 and reported elevated nocturnal GH and serum IGF-1, with lean body mass gain in men 09. Vittone and colleagues reported that single nightly GHRH (1-29) injections in healthy elderly men restored 24-hour integrated GH toward levels typical of younger adults 10.
Where Sermorelin Sits in the GHRH-Analog Class
Sermorelin is the shorter, shorter-half-life member of a class. Tesamorelin, a stabilized GHRH 1-44 analog with a trans-3-hexenoic acid modification, carries a substantially longer plasma half-life and an FDA indication for HIV-associated lipodystrophy — Falutz and colleagues reported a 15.2% versus 5.0% visceral-adipose reduction at 2 mg subcutaneously daily for 26 weeks 13. PEGylation and D-Ala2 substitution have produced further long-acting GHRH analogs 16, bracketing Sermorelin in the analog landscape.
The ghrelin-receptor (GHS-R1a) agonists — ipamorelin among them — operate on a second, independent secretagogue pathway 14. Combined GHRH + GHRP stimulation has been reported to produce a supra-additive GH pulse versus either agent alone, consistent with two independently coupled receptor systems converging on the same somatotroph population 1215. See the full Sermorelin vs ipamorelin and Sermorelin vs tesamorelin comparisons on /research.
What is Sermorelin?
Sermorelin is a synthetic 29-amino-acid peptide corresponding to the bioactive N-terminal fragment of growth hormone-releasing hormone (GHRH 1-29), studied as a stimulator of endogenous growth hormone secretion. The full sequence is Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-NH2 01.
What This Site Is
Medicine Sermorelin is an independent editorial project that publishes summaries of the peer-reviewed Sermorelin and GHRH (1-29) research literature. We do not sell anything. We do not provide medical advice. We are not a clinic, not a pharmacy, not a telehealth service. The 'medicine' in the domain name is editorial framing — a position relative to the clinical research literature, not a claim about services rendered.
What we do publish: the mechanism, the pharmacokinetics, the pediatric and adult trial record, the safety profile reported in published trials, the regulatory history (FDA approval of the historical FDA-approved branded sermorelin in 1997, voluntary discontinuation in 2008 17), and the comparative pharmacology of the GHRH-analog and GH-secretagogue classes. The full bibliography lives on the published references page. The frequently asked questions collect the twenty-five most-asked queries with cited, direct answers.
We also publish a Sermorelin dosage in the research literature page documenting the doses, routes, and pharmacokinetic envelope reported in published studies, and a Sermorelin side effects page covering the adverse-event profile, contraindications, and the honest limits of the long-term safety dataset. None of these pages is a treatment recommendation; the framing throughout is studied-at, not prescribed.