# Sermorelin MD — A drawn reading of the GHRH(1-29) literature > Sketchnoted summaries of the sermorelin research: a 29-residue GHRH analog that asks the pituitary to release its own growth hormone. Mechanism, half-life, regulatory status, references. GHRH(1-29) — 29 amino acids, an 11-12 minute plasma half-life, one pituitary receptor, and a lot of footnotes. The literature, sketched. ## Before you open the notebook Sermorelin is a short chain of 29 amino acids — the same 29 that begin the brain's own growth hormone-releasing hormone (GHRH). When it reaches the pituitary gland (a small structure at the base of the brain), it asks the gland to release the body's own growth hormone in its normal rhythm. It does not contain growth hormone itself. The cleanest human evidence sits in two places: children with a diagnosed growth-hormone shortage grew faster on sermorelin, and short-term studies of older men showed GH and IGF-1 (a downstream hormone the liver makes after a GH pulse) returning toward younger-adult levels [2][3]. The branded product — Geref — was approved by the FDA in 1997 and pulled from the US market in 2008 for business reasons, not safety problems [2][7]. Today it is compounded by licensed pharmacies on prescription. What people report using it for — and the honest limits of the evidence — are on [the effects page](/effects). ## Start with the shape of the molecule To understand sermorelin, start with the chain. Sermorelin is the first 29 amino acids of human growth hormone-releasing hormone (GHRH), the hypothalamic peptide that tells the pituitary to make GH. The full endogenous hormone is 44 residues long, but the first 29 happen to carry essentially all of the receptor-binding activity [1][2]. Trim everything past residue 29, cap the C-terminus with an amide, and the molecule still does the job. That is what sermorelin is: GHRH(1-29)-NH2. A 3,358-dalton synthetic peptide with the same N-terminal address as the body's own GHRH and the same downstream effect on the anterior pituitary somatotroph cells that produce growth hormone [1]. Which means sermorelin is not growth hormone. It is the signal that asks for growth hormone. The pituitary still has to be willing — and able — to answer. ## What the pituitary does when it hears the signal Somatotrophs carry a Gs-coupled G-protein-coupled receptor called GHRH-R. When sermorelin binds it, adenylyl cyclase fires, intracellular cAMP rises, protein kinase A phosphorylates the transcription factor CREB and the pituitary-lineage factor Pit-1, and two things happen in sequence: GH gene transcription ramps up and preformed GH-loaded secretory granules fuse with the cell membrane and release their cargo [1][10]. That is the canonical pathway, and a comprehensive 2025 review of GHRH-R signaling reaffirmed it as the spine of the response — with MAPK/ERK and PI3K-Akt arms also active in peripheral tissues like cardiomyocytes, where the receptor has cytoprotective roles separate from GH release [10]. The subtlety is the brake. Somatostatin, a hypothalamic peptide that opposes GHRH, sets a ceiling on what any GHRH analog can produce. Push sermorelin into a pituitary, and you get a pulse of GH; push harder, and somatostatin pushes back. This negative feedback is the reason the literature describes GHRH analogs as physiologic rather than supraphysiologic — the body's own circuit is still in charge [8]. ## Why the half-life chart looks the way it does Plasma half-life of sermorelin in humans is about 11-12 minutes [7]. That is short. Peak plasma concentrations land 5-20 minutes after subcutaneous dosing, and circulating drug is essentially gone by the half-hour mark. The GH response is not gone. Stimulated GH secretion can persist for roughly three hours after a single subcutaneous dose, because the half-life that matters is the half-life of the downstream effect on the somatotroph, not the half-life of the ligand at the receptor [7]. Sermorelin's job is to start the conversation; the pituitary keeps it going. This short pharmacokinetic window is also why the published research dosing concentrates at night. Endogenous GH pulses are biggest during slow-wave sleep, so the conventional nightly subcutaneous schedule in the trial literature aligned the exogenous signal with the body's most receptive window [3][4][15]. ## The Geref chapter, briefly Sermorelin acetate was FDA-approved in 1997 for treatment of idiopathic growth hormone deficiency in children, marketed under the brand name **Geref**, and approved separately as a diagnostic GH-stimulation test agent (Geref Diagnostic) [14]. The pediatric trial that anchored the approval enrolled 110 GH-deficient prepubertal children given 30 mcg/kg nightly subcutaneously and observed mean height velocity rise from 4.1 to 8.0 cm/year over the first six months [2]. In 2008, the manufacturer voluntarily discontinued commercial production [12]. There has been no FDA-approved finished sermorelin product on the U.S. market since. A 2024 clinical update on adult growth hormone deficiency notes that the absence of recombinant GHRH for stimulation testing has shifted diagnostic protocols toward macimorelin and glucagon-based testing [12]. Sermorelin itself did not disappear. It is currently dispensed in the U.S. only through 503A and 503B compounding pharmacies on physician prescription. Research and editorial interest in the molecule has been renewed — partly because the GHRH-analog class as a whole (sermorelin's close cousin tesamorelin in particular) keeps producing positive trial data in metabolic indications [11], and partly because the original pediatric and aging trials still hold up on re-reading. ## What this notebook is **Sermorelin MD** is an editorial project. The 'MD' is short for *mechanism diagrams* — every page on this site is a hand-drawn, citation-anchored reading of one part of the published sermorelin record. We are not a clinic. We do not prescribe, dispense, or sell anything. We summarize the literature with the same plain attention that a careful student would give a stack of papers before a seminar. The pages are organized the way a researcher would actually want them. The **research** page walks through mechanism and the strongest trials, with figures sketched for what the prose can only describe. The **dosage** page collects what the published research used — doses, routes, durations — without recommending anything for use. The **FAQ** answers the ten questions readers ask most often about sermorelin. The **references** page is a numbered list of every paper this site cites, with DOIs and PubMed links. Start anywhere. The notebook is open. --- A citation-anchored sketchnote of the sermorelin literature — not a clinic, not a vendor, and not a substitute for a physician.