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Mechanism And Regulatory Status — Quick Reference

By Editorial Desk · published 2026-05-27 · last reviewed 2026-07-09 · Guide

hGH fragment is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.

Last reviewed on 2026-07-09. Where a claim depends on a specific study, the study is described rather than over-claimed.

Mechanism and Regulatory Status

Regulatory treatment of AOD-9604 is shaped by its classification as a peptide hormone. The World Anti-Doping Agency lists it as a prohibited substance, and many national anti-doping organizations adopt that list. It does not hold approval as a prescription medicine in the United States, the European Union, or other major markets. Products sold online are frequently labeled for research use only and may not undergo independent quality testing. Import and possession rules differ by country, so legal status depends on local law.

Proposed mechanisms for AOD-9604 focus on fat cells. Laboratory studies suggest the peptide can increase lipolysis, the breakdown of stored fat, and reduce lipogenesis, the formation of new fat. Unlike full human growth hormone, it does not appear to stimulate substantial IGF-1 production in the studies reported so far. Some evidence points to beta-adrenergic signaling, but the precise receptor targets and downstream pathways remain unresolved. The fragment is not thought to act through the classical growth hormone receptor.

Clinical development of AOD-9604 included trials in people with obesity. Reports from early-phase and mid-phase studies described modest or inconsistent changes in body weight. A phase IIb program did not meet its primary endpoint, and the compound was not approved for medical use. Differences in formulation, delivery route, and participant characteristics may explain some of the variation. Later investigations explored whether the peptide might have effects in other tissues, including cartilage.

Background And Research Context

In the scientific literature, AOD-9604 appears in reviews of growth hormone fragments and in discussions of peptide-based metabolic research. Some sources distinguish it from growth hormone itself, while others group it with compounds marketed for weight management. The evidence base is small compared with approved obesity medications. Questions about long-term efficacy and clinical relevance remain open, and independent replication of key findings is limited. Most published reports are early-stage and exploratory.

AOD-9604 is a synthetic peptide modeled on the C-terminal region of human growth hormone. It is often described as hGH fragment 176-191. Research interest arose because it was designed to isolate possible effects on fat metabolism from other actions of growth hormone. It is not a full growth hormone molecule. Its development history includes early laboratory and animal studies followed by human trials. The peptide has been examined in laboratory, animal, and limited human studies.

Aod-9604 at a glance

PropertyValueNotes
Typical storage temperature-20 °CLyophilized peptide; protect from moisture and light.
Typical analytical methodHPLC and mass spectrometryUsed to confirm identity and estimate purity.
Common synonymsAOD9604; hGH 176-191Naming varies by supplier and publication.
Disulfide bondsOneAffects folded structure and stability.
Typical research purity≥95%Value depends on supplier and analytical method.

Measurement and Storage Practices

Stability of AOD-9604 depends on storage conditions. Lyophilized powder is generally more stable than reconstituted solution. Recommended storage is typically at -20°C or lower, protected from light and moisture. Repeated freeze-thaw cycles can cause aggregation or degradation. In solution, the peptide may be susceptible to hydrolysis or oxidation, so aliquoting and cold storage are common practices. Researchers often add stabilizers such as mannitol or trehalose during lyophilization to improve shelf life.

Quality control for AOD-9604 involves verifying identity, purity, and concentration. Suppliers may provide a certificate of analysis listing HPLC purity and mass spectrometry data. Independent verification is advised because peptide products can vary in quality. Researchers should check for counterions, residual solvents, and microbial contamination. Proper documentation supports reproducibility and safety in laboratory studies. When sourcing, institutions often require third-party testing and detailed chain-of-custody records. These steps help ensure that experimental results are attributable to the peptide rather than impurities.

Analytical characterization of AOD-9604 typically employs reversed-phase high-performance liquid chromatography (RP-HPLC) to assess purity and identity. Mass spectrometry provides confirmation of molecular mass, while amino acid analysis can verify composition. These methods are standard for peptide research chemicals. Because the peptide lacks a distinct chromophore, detection often relies on ultraviolet absorbance at 214 nm or mass spectrometric response. Laboratories may also use capillary electrophoresis for separation. For example, size-exclusion chromatography can detect aggregates.

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Identity and Research Context

Early interest in AOD-9604 centered on whether a fragment of human growth hormone could influence fat metabolism without the broader effects of the full hormone. Cell and animal studies reported changes in fat storage and breakdown. Human trials followed, but the results were not strong enough to secure regulatory approval. The compound remains available for laboratory research, and its clinical potential is still described as uncertain. Studies continue to examine its activity and safety profile.

AOD-9604 is a synthetic peptide that corresponds to a short section of human growth hormone. It is commonly identified as hGH fragment 176-191 because its sequence matches residues at the C-terminal end of the hormone. The molecule contains sixteen amino acids and is made by solid-phase peptide synthesis. Researchers study it for metabolic effects rather than for the growth-promoting actions associated with full human growth hormone. Its small size distinguishes it from the complete 191-amino-acid hormone.

Reference notes

2-hydroxyisoflavanone synthase (EC 1.14.14.87, CYT93C, IFS, isoflavonoid synthase) is an enzyme with systematic name liquiritigenin,NADPH:oxygen oxidoreductase (hydroxylating, aryl migration). It catalyses a rearrangement reaction which converts flavonoids into isoflavones, for example:

== Functions == Some fusion proteins combine whole peptides and therefore contain all functional domains of the original proteins. However, other fusion proteins, especially those that occur naturally, combine only portions of coding sequences and therefore do not maintain the original functions of the parental genes that formed them. Many whole gene fusions are fully functional and can still act to replace the original peptides. Some, however, experience interactions between the two proteins that can modify their functions. Beyond these effects, some gene fusions may cause regulatory changes that alter when and where these genes act. For partial gene fusions, the shuffling of different active sites and binding domains have the potential to result in new proteins with novel functions.

A genome-wide study of convergence published in 2013 analysed 22 mammal genomes and revealed that tens of genes have undergone the same replacements in echolocating bats and cetaceans, with many of these genes encoding proteins that function in hearing and vision. Both the aye-aye lemur and the striped possum have an elongated finger used to get invertebrates from trees. There are no woodpeckers in Madagascar or Australia where the species evolved, so the supply of invertebrates in trees was large. Castorocauda, a Jurassic Period mammal and beavers both have webbed feet and a flattened tail, but are not related. Prehensile tails evolved in a number of unrelated species marsupial opossums, their Australasian cousins, kinkajous, New World monkeys, tree-pangolins, tree-anteaters, porcupines, rats, skinks and chameleons, and the salamander Bolitoglossa. Pig form, large-headed, pig-snouted and hoofs are independent in true pigs in Eurasia, peccaries in South America and the extinct entelodonts. Tapirs and pigs look much alike, but tapirs are perissodactyls (odd-toed ungulates) and pigs are artiodactyls (even-toed ungulates). Filter feeding: baleen whales like the humpback and blue whale (mammals), the whale shark and the basking shark separately, the manta ray, the Mesozoic bony fish Leedsichthys, and the early Paleozoic anomalocaridid Aegirocassis have separately evolved ways of sifting plankton from marine waters. The monotreme platypus has what looks like a bird's beak (hence its scientific name Ornithorhynchus), but is a mammal.

=== October === 1 October – HM Coastguard's Search and Rescue unit suspends landings at most of Scotland's hospital helipads amod safety concerns. 2 October – Scottish gangland boss Jamie "Iceman" Stevenson is sentenced to 20 years in prison after admitting to orchestrating a plot to smuggle £100m worth of cocaine from South America in boxes of bananas. Data from the Scottish Government has indicated that 57 of the 477 prisoners released early to ease prison overcrowding were back in custody before the date of their original release, including 12 who were back in prison within ten days. 4 October – Data from Police Scotland indicates that instances of recorded hate crime have increased by 63% since the Hate Crime and Public Order Act became law in April. 5 October – Four people are treated in hospital after being struck by a taxi in central Glasgow. 6 October – A man is killed and three other people taken to hospital following an explosion at a block of flats in Alloa, Clackmannanshire. 8 October – MSPs back a nonbinding SNP motion by 99 votes to 14 calling on the UK government to reconsider their policy on winter fuel payments. 9 October – Transport Secretary Fiona Hyslop announces that the public will be consulted on reducing speed limits in Scotland following an increase in the number of deaths on the roads. The Crown Office announces it has dropped charges of human trafficking against businesswoman Ann Gloag.

=== Pharmacodynamics === Iso-LSD shows significant affinity for serotonin receptors. It had an affinity (IC50Tooltip half-maximal inhibitory concentration) of about 200 nM for serotonin receptors in rat brain membranes. For comparison, LSD had an affinity of about 8 to 10 nM in the studies, while isoergine had an affinity of 100 to 200 nM and ergine (LSA) had an affinity of about 200 nM. Hence, iso-LSD showed about 10- to 30-fold lower affinity for serotonin receptors than LSD but had similar affinity for the receptors as ergine and isoergine. Despite these findings however, iso-LSD showed only 0.12% of the antiserotonergic activity of LSD (~1,000-fold lower in comparison) in the isolated rat uterus. In studies by David E. Nichols and colleagues, iso-LSD fully substituted for LSD in rodent drug discrimination tests. Full substitution occurred at a dose of 0.32 mg/kg and its ED50Tooltip median effective dose was 0.14 mg/kg, whereas the LSD training dose was 0.08 mg/kg. Iso-LSD was about 7 times less potent than LSD in terms of ED50 in this assay. In other studies, the drug had about 3.7% of the toxic potency of LSD in rabbits (presumably in terms of LD50Tooltip median lethal dose) and, unlike LSD, was not pyretogenic.

Sources: en.wikipedia.org

Notes from published material

== Uses == iRGD peptides have been shown to increase accumulation and penetration of anticancer drugs into tumors, but not into normal tissues – whether the drug is coupled to the peptide or given together with it. iRGD-mediated increased penetration and anti-cancer efficacy have been demonstrated with a variety of anti-cancer small molecules, nanoparticles and antibodies. Lisata Therapeutics Inc. is currently testing iRGD-based therapy called certepetide (aka LSTA1; CEND-1) in clinical studies in solid-tumor patients. The U.S. Food and Drug Administration (FDA) awarded certepetide orphan drug status in 2019, and fast-track designation in 2020.

== Biography == He is a member of the editorial board of the journal Intelligence. His PhD was completed in 1994 at the University of Auckland (New Zealand) and integrated the Eysenckian dimensional model of psychosis with the categorical model of schizotypy proposed by Paul E. Meehl, using measures of personality, creativity, evoked potentials, and smooth pursuit eye movement dysfunction. The title of his doctoral thesis was Psychometric & psychophysiological measures for schizotypy, creativity & psychoticism. Subsequent academic publications include demonstrating the existence of two separate forms of dyslexia, underpinned by distinct genes, and, subsequently, demonstrating that the genes associated with dyslexia are also linked to normal variation in reading ability. This work lead to searches for specific genes involved in reading and language. In positive psychology, he showed (along with Alexander Weiss and Michelle Luciano) that the genes for happiness are genes for personality, suggesting that a general factor of genetic well-being and specific genetic influences from the five factor model traits of Extraversion, Neuroticism/Stability, and Conscientiousness completely explain the heritable component of differences in happiness. With Caroline Rae, Bates showed that creatine supports cognitive function – finding that creatine supplements in vegans substantially increased their cognitive ability and working memory by comparison with placebo. This supported a literal 'mental energy' model of intelligence, first postulated by Charles Spearman.

Free movement of goods within the European Union is achieved by a customs union, and the principle of non-discrimination. The EU manages imports from non-member states, duties between member states are prohibited, and imports circulate freely. In addition under the Treaty on the Functioning of the European Union article 34, 'Quantitative restrictions on imports and all measures having equivalent effect shall be prohibited between Member States'. In Procureur du Roi v Dassonville the Court of Justice held that this rule meant all "trading rules" that are "enacted by Member States" which could hinder trade "directly or indirectly, actually or potentially" would be caught by article 34. This meant that a Belgian law requiring Scotch whisky imports to have a certificate of origin was unlikely to be lawful. It discriminated against parallel importers like Mr Dassonville, who could not get certificates from authorities in France, where they bought the Scotch. This "wide test", to determine what could potentially be an unlawful restriction on trade, applies equally to actions by quasi-government bodies, such as the former "Buy Irish" company that had government appointees. It also means states can be responsible for private actors. For instance, in Commission v France French farmer vigilantes were continually sabotaging shipments of Spanish strawberries, and even Belgian tomato imports. France was liable for these hindrances to trade because the authorities 'manifestly and persistently abstained' from preventing the sabotage.

In blood serum, the content of nitrogenous substances such as urea and creatinine (uremia or azotemia) and phosphate (hyperphosphatemia). The increased phosphate concentration is the result of the reduced glomerular filtration rate. Among other things, fibroblast growth factor 23 (FGF-23) is involved here, which is more sensitive than the phosphate level in the event of an incipient disorder. The potassium content is usually reduced (hypokalemia), but can also be increased—the reverse is true for the sodium content. If the cause of the kidney disease lies in the renal corpuscles, albumin deficiency (hypalbuminemia) and excess cholesterol (hypercholesterolemia) also occur. The determination of cystatin C is not evaluated for cats, this protein can also be elevated in cats with hyperthyroidism or with glucocorticoids and drop sharply for several hours after food intake. Recent studies suggest that symmetric dimethylarginine (SDMA) is a suitable marker for renal function in cats. The SDMA concentration in serum shows close correlations with the glomerular filtration rate and the creatinine concentration. It can already detect a 40% loss of kidney function, i.e. before there is an increase in creatinine in the blood. The most sensitive method of kidney function diagnostics is the direct determination of the glomerular filtration rate via the clearance, which is already reduced in chronic kidney disease before azotemia occurs. Various substances have been evaluated for cats, the most practical being creatinine and iohexol.

Sources: en.wikipedia.org

Frequently asked questions

Is AOD-9604 approved for weight loss?

No. Major drug regulators have not approved AOD-9604 for weight loss or any other therapeutic indication. It remains an investigational compound studied in research settings.

Why is AOD-9604 banned in sports?

The World Anti-Doping Agency classifies it as a prohibited peptide hormone. Athletes under anti-doping rules are not permitted to use it. Its presence can trigger a doping violation.

Does AOD-9604 raise growth hormone levels?

It is a fragment of growth hormone rather than a substance that signals the pituitary to release more hormone. Studies have not shown a consistent rise in IGF-1 or full growth hormone. Its metabolic effects, if any, appear separate from those of the complete hormone.

What is AOD-9604?

It is a synthetic peptide fragment derived from the C-terminal region of human growth hormone, commonly referred to as hGH fragment 176-191. It has been investigated for effects on fat metabolism, but it is not an approved medication in most jurisdictions.

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