Sermorelin

What Is Sermorelin?

Sermorelin is a synthetic peptide identical to the first 29 amino acids of human growth hormone-releasing hormone (GHRH), with an amide at the C-terminus. It acts on the pituitary to stimulate the release of the body’s own growth hormone (GH), rather than supplying GH directly.

Reviews classify sermorelin with other growth hormone secretagogues, such as GHRP-2, GHRP-6, ibutamoren and ipamorelin, describing the group as potent stimulators of GH and insulin-like growth factor 1 (IGF-1). The same reviews note that clinical data on many of these compounds remain sparse.^[1]

Sermorelin is also known as GRF(1-29)NH2, hGHRH(1-29)NH2 and growth hormone-releasing factor (1-29) amide in chemical databases. In recent sports medicine literature it appears among peptides marketed directly to patients for injury recovery and performance, a setting in which reviewers describe rigorous human safety data as scarce.^[2]

Chemical Structure and Molecular Identity

Sermorelin is a 29-residue peptide amide with the molecular formula C149H246N44O42S and a molecular weight of 3357.9 g/mol (PubChem CID 16132413). Its sequence, 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, matches positions 1 to 29 of human GHRH.

The single sulfur atom comes from methionine at position 27. PubChem lists the InChIKey WGWPRVFKDLAUQJ-MITYVQBRSA-N, the CAS number 86168-78-7 and the UNII 89243S03TE. The ATC codes H01AC04 and V04CD03 place it among somatropin agonists and among diagnostic agents for pituitary function.

Structure-activity research

Early structure-activity studies used human GRF(1-29)-NH2 as the reference peptide. In rat anterior pituitary membranes, substituting a D-amino acid at position 2 was the only D-isomer change that produced a superagonist, with half-maximal adenylate cyclase activation at about half the concentration needed for GRF(1-29)-NH2. D-isomers at positions 1 and 3 had no effect, while D-isomers at positions 4, 6 or 7 reduced affinity.^[3]

A companion study in rat pancreatic membranes found that GRF analogues also bind vasoactive intestinal peptide (VIP) receptors. Changes at positions 6 and 7 markedly reduced affinity, while D-Ala2 and Phe4 substitutions gave superagonists.^[4] D-alanine at position 2 is one of the four substitutions found in the later analogue CJC-1295. PubChem’s synonym list for sermorelin also records several single D-amino acid variants of GRF(1-29)-NH2, at positions 2, 3 and 8, reflecting this period of analogue work.

Research History and Development

Sermorelin emerged from 1980s research on growth hormone-releasing factor (GRF), when the 29-residue amidated fragment became a standard reference peptide for receptor and analogue studies. By 1985, investigators were systematically substituting its N-terminal residues to map receptor activation.^[3][4]

Sermorelin acetate was later approved by the US Food and Drug Administration, including for children with growth hormone deficiency. A 2006 editorial asked whether sermorelin might be a better approach to managing adult-onset growth hormone insufficiency.^[5] The approved product was discontinued in the United States in 2008 for business reasons, and FDA later determined that it had not been withdrawn for reasons of safety or effectiveness.

Subsequent literature moved in two directions. Clinical reviews examined sermorelin as a possible adjunct in men with hypogonadism, metabolic syndrome or subclinical hypogonadism.^[1] Anti-doping laboratories, meanwhile, developed methods to detect sermorelin and its metabolites in urine.^[6][7] Reviews of performance-enhancing peptides now describe GHRH analogues such as sermorelin as marketed to athletes and bodybuilders as more selective and ostensibly safer alternatives to anabolic steroids.^[8]

Mechanisms Studied in Research

Sermorelin acts as an agonist at the GHRH receptor on anterior pituitary cells, where receptor binding activates adenylate cyclase and triggers GH release. GH then raises circulating IGF-1, which mediates many of its downstream effects.^[3][1]

Receptor selectivity

Using a GRF antagonist, (N-Ac-Tyr1,D-Arg2)-GRF(1-29)-NH2, researchers showed that GRF and VIP receptors are distinct entities in the rat anterior pituitary.^[3] In rat pancreatic tissue, however, GRF analogues interacted with VIP-preferring receptors, and one analogue, (N-Ac-Tyr1,D-Phe2)-GRF(1-29)-NH2, acted as a VIP antagonist.^[4]

Downstream signaling

An orthopedic review groups sermorelin with ipamorelin, CJC-1295, tesamorelin and AOD-9604 as secretagogues proposed to activate IGF-1 signaling and satellite cell repair, while noting a current lack of clinical trials for these uses.^[9]

Metabolism

In vitro metabolism work on four large GHRH analogues identified 19 major metabolites. Sermorelin(3-29)-NH2, a metabolite lacking the first two residues, is used alongside the parent peptide as a reference material for detection.^[6]

Key Findings From Published Studies

Published findings on sermorelin center on receptor pharmacology in rat tissue, analytical detection methods and reviews of its clinical potential; the sources compiled for this page do not include primary clinical trial data.

Receptor pharmacology (in vitro)

The N-acetylated analogue of GRF(1-29)-NH2 was as potent and active as the parent peptide at rat pituitary adenylate cyclase, and the residue at position 2 of that analogue determined whether it acted as a full agonist, partial agonist or competitive antagonist.^[3] Acetylation of the free N-terminal amino group and D-isomer replacement of Asp3, Ala4, Phe6 and Thr7 reduced intrinsic activity at rat pancreatic receptors. Substitutions with para-chloro-phenylalanine or tryptophan at position 6 also lowered intrinsic activity, and the (N-Ac-Tyr1,D-Phe2) analogue selectively inhibited both VIP- and GRF-stimulated adenylate cyclase activity in that tissue.^[4]

Detection in urine

A 2021 liquid chromatography-tandem mass spectrometry method detected sermorelin, tesamorelin and both forms of CJC-1295 in fortified urine, with limits of detection generally at or below 1 ng/mL, the World Anti-Doping Agency (WADA) required performance limit.^[6] A 2023 triple quadrupole UHPLC-MS/MS method using weak cation-exchange solid-phase extraction reached a limit of detection of 0.2 ng/mL and a limit of quantification of 0.6 ng/mL for GHRHs including sermorelin and sermorelin(3-29)-NH2, and was validated for routine anti-doping screening.^[7]

Clinical reviews

A 2020 review concluded that growth hormone secretagogues including sermorelin may help with fat gain and muscle atrophy in hypogonadal men, but that a paucity of clinical data limits understanding of their role.^[1] A 2026 doping review states that clinical evidence for peptide use in sport is limited and that most published studies used controlled therapeutic conditions rather than the combined regimens common in bodybuilding.^[8]

Evidence gaps

Across these sources, the same limitation recurs. The 2020 review calls the lack of clinical data an opportunity for future investigation, and a 2026 orthopedic review notes that promising preclinical work on growth hormone secretagogues has not been matched by clinical trials.^[1][9] Questions about long-term outcomes, comparative effects against other GHRH analogues and relevance to musculoskeletal repair remain open in the literature summarized here.

Because sermorelin differs from close analogues by only a few residues, researchers typically verify it with HPLC purity and mass spectrometry identity data.

Regulatory and Research Status

Sermorelin is not currently marketed in the United States as an FDA-approved drug product. Sermorelin acetate was previously approved, but the manufacturer discontinued it in 2008 for business reasons, and FDA later determined that the withdrawal was not for reasons of safety or effectiveness.

In sport, WADA prohibits GHRH and its synthetic analogues, including sermorelin. Detection remains difficult because of low urinary concentrations and limited knowledge of metabolism, which has driven the development of more sensitive mass spectrometry methods.^[6][7]

Recent reviews place sermorelin among peptides promoted for muscle growth, fat metabolism and recovery, and they warn that products in unregulated supply chains are often mislabeled or contaminated.^[8] Sports medicine authors also emphasize that rigorous human safety data are scarce for many peptides marketed directly to patients.^[2]