Sermorelin: four decades of pulse-physiology research, indexed and cited.

> SIGNAL OVERVIEW / PLAIN READ

Sermorelin is a 29-amino-acid peptide that tells the pituitary gland to release the body's own growth hormone. It does not introduce GH directly — it fires the signal upstream, so the pituitary's own feedback controls stay on. That is the mechanistic argument for it over injecting GH directly.

In pediatric trials it accelerated growth in GH-deficient children. In elderly adult cohorts it raised GH and IGF-1 (the messenger the liver makes in response to GH), with downstream shifts in body fat and lean mass over six months. One six-month study also documented improvements in cognitive performance.

The compound was FDA-approved for pediatric GH deficiency (Geref, 1997) and commercially withdrawn in 2008 for business reasons, not safety. It is now available through compounding pharmacies. WADA prohibits it in sport.

For what people actually report — benefits and adverse effects — see the effects page.

What Is Sermorelin?

Sermorelin is a synthetic 29-amino-acid peptide — the shortest N-terminal fragment of endogenous human growth hormone-releasing hormone (GHRH) that retains full GHRH-receptor binding affinity and GH-stimulating activity ^[1]. Molecular weight: 3358 Da. CAS: 86168-78-7. Synonym set: GHRH(1-29)-NH2, GRF(1-29)NH2, Sermorelin Acetate.

The peptide binds GHRH receptors (GHRH-R) on pituitary somatotroph cells. Signal cascade: adenylyl cyclase activation → cAMP elevation → PKA activation → voltage-gated calcium channel opening → pulsatile GH exocytosis. The hypothalamic-pituitary-somatostatin feedback axis remains intact throughout — endogenous somatostatin periodically withdraws, producing episodic GH peaks rather than sustained square-wave GH elevation ^[9].

The pituitary's own feedback loops stay online. That is the mechanistic distinction from exogenous recombinant human GH (rhGH): sermorelin prompts the pituitary to secrete its own GH; it does not introduce GH directly.

For the sermorelin mechanism of action, see the research console.

Sermorelin as a Research Peptide: Mechanism and Context

The sermorelin peptide belongs to the GHRH-analog class — structurally related to endogenous GHRH(1-44) but truncated to the active 29-residue N-terminal fragment. It is classified as a GH secretagogue: a compound that stimulates secretion of another substance rather than providing it directly.

GH secretion declines approximately 15% per decade after the third decade of life ^[14]. By age 55, daily GH secretion has fallen to roughly 25 mcg/kg/day versus puberty peaks of approximately 150 mcg/kg/day ^[14]. The primary mechanism is reduction in nocturnal GH pulse amplitude — not pulse frequency — linked to relative GHRH deficiency and increased somatostatin tone ^[14]. That mechanistic profile makes GHRH analogs a targeted intervention for age-related somatotropic decline.

Sermorelin was FDA-approved (as Geref, NDA 20-443) for pediatric GH deficiency in 1997 ^[15]. Manufacturer voluntarily withdrew the products in 2008–2009 — not for safety or efficacy reasons, per FDA's 2013 determination ^[15]. Now available via 503A/503B compounding pharmacies as a compounded prescription medication.

What Is Sermorelin Used for in Research?

Clinical research has studied sermorelin in three population categories:

Pediatric GH deficiency. The Geref International Study Group (1996) enrolled 110 prepubertal children with GHD. Outcome: height velocity increased from 4.1 cm/yr at baseline to 8.0 cm/yr at 6 months at 30 mcg/kg/day subcutaneous ^[1]. 74% showed good response at 6 months. Bone age ratio remained normal (1.04 ± 0.58) ^[1].

Adult GH-axis decline and body composition. Six-month daily bedtime sermorelin at approximately 1 mg in healthy elderly men produced a 35% increase in IGF-1, approximately 5% decrease in body fat, and a reciprocal increase in lean body mass ^[6]. Nocturnal GH secretion increased significantly but full pulsatile restoration was not achieved ^[6].

Cognitive function. Six months of daily GHRH (sermorelin acetate) in 89 healthy older adults improved performance IQ, picture arrangement, and psychomotor processing speed (p<0.01) ^[7]. A 20-week tesamorelin-analog trial in 152 adults — including those with mild cognitive impairment — produced significant executive function improvement (p=0.005) and a 117% IGF-1 increase ^[11].

For full sermorelin body composition research, see the research page.

Is Sermorelin a Steroid?

No. Sermorelin is a 29-amino-acid peptide — not a steroid. Steroids are cholesterol-derived molecules with a four-ring carbon skeleton; peptides are short amino acid chains. The mechanisms of action, receptor targets, and regulatory classifications are entirely different.

Sermorelin Acetate: The Salt Form Used in Research

Sermorelin acetate is the acetate salt of GHRH(1-29)-NH2 — the form used in the original Geref preparation and in subsequent clinical trial formulations. The acetate counterion aids aqueous solubility and lyophilization stability. Supplied as a lyophilized white powder; reconstituted with bacteriostatic or sterile water prior to subcutaneous injection. Molecular weight of the acetate salt form is approximately 3358 Da for the free base peptide chain.

For sermorelin administration timing and storage data, see the dosage page.

Sermorelin Classification: GHRH Analog Peptide

Classification: peptide / GHRH analog. Category node: GH secretagogue — GHRH-receptor agonist class. Not a steroid, not a steroid precursor, not a SARM, not a small molecule. WADA classification: prohibited under S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics) ^[16]. Regulatory status in the U.S.: formerly FDA-approved (NDA 20-443, pediatric GHD, 1997–2009); now available as a compounded prescription medication via 503A/503B pharmacies ^[15].