AOD-9604 is a synthetic 16-residue peptide derived from the C-terminal fragment of human growth hormone, residues 176 to 191, with an extra tyrosine added at the N-terminus. It was developed on the premise that the lipolytic activity of growth hormone could be separated from its growth-promoting and glucose-related activity — the fragment retains the region associated with fat metabolism in the published literature while lacking the receptor-binding surfaces needed for the IGF-1 axis. We supply research-grade AOD-9604 as lyophilized powder in sealed vials, for laboratory use only.
What is AOD-9604, precisely
Human growth hormone is a 191-residue protein. Work published from the 1990s onward reported that its effects on adipose tissue could be reproduced by a short C-terminal region, and that this region did not require the intact hormone or the growth hormone receptor dimerisation that drives IGF-1 production. AOD-9604 — the initials stand for anti-obesity drug — is the engineered version of that fragment: hGH(177-191) with a tyrosine prepended, giving 16 residues in total. The added tyrosine improves synthetic handling and provides a UV chromophore, which is genuinely useful analytically because it makes the peptide detectable at 280 nm.
The disulfide bridge between the two cysteines in the native fragment is retained, forming the small loop that the reported activity depends on. It is a true fragment peptide, not an analog of the whole hormone, and it is not growth hormone in any functional sense.
Origin and structure
- Parent sequence. Human growth hormone residues 177-191, the C-terminal segment.
- Modification. An N-terminal tyrosine, distinguishing AOD-9604 from the unmodified HGH Fragment 176-191.
- Disulfide bridge. An intramolecular Cys-Cys bond forming the loop required for the reported activity — reflected in the two sulfur atoms in the formula.
- Identifiers. CAS 221231-10-3, formula C78H123N23O23S2, molecular weight 1815.08 Da.
At roughly 1.8 kDa this is a small peptide by the standards of the metabolic field, which has practical consequences: it dissolves readily in aqueous buffers, it is more stable to handling than a large acylated peptide, and it clears quickly, since there is no albumin-binding lipid and nothing to slow renal filtration.
How AOD-9604 is thought to work
The proposed mechanism is honestly less settled than the marketing around this peptide suggests, and a research page should say so. Published preclinical work has reported that the fragment stimulates lipolysis and inhibits lipogenesis in adipose tissue, with effects described in isolated adipocytes and in rodent models of obesity. Several papers have implicated beta-3 adrenergic receptor signalling in adipose tissue, though the relationship is described as indirect or permissive rather than as direct receptor agonism, and results in beta-3 knockout models have complicated the picture rather than confirming it.
What is comparatively well supported is the negative claim the molecule was designed around: unlike intact growth hormone, AOD-9604 has not been reported to raise IGF-1 or to produce the growth-promoting effects associated with growth hormone receptor activation. That dissociation is the intellectually interesting part of the molecule and the reason it appears in adipose tissue research as a probe for growth-hormone-independent lipolytic signalling.
What research has examined
- Adipocyte studies. Isolated adipocyte and cultured cell work measuring glycerol and free fatty acid release, lipogenic enzyme activity, and lipolytic signalling. This is the core of the evidence base.
- Rodent studies. Body composition and adiposity in obese mouse and rat models, with the reported separation from IGF-1 elevation a recurring endpoint.
- Human clinical trials. Early-phase trials were conducted, and published results did not demonstrate the weight outcomes the preclinical work had suggested. This is an important and frequently omitted part of the AOD-9604 story: the translational gap between rodent adipocyte findings and human results is the main reason the molecule never advanced to approval.
- Cartilage and joint work. A smaller strand of preclinical literature has examined the fragment in cartilage and osteoarthritis models, unrelated to its metabolic origins.
For a fuller account of the two lipolytic fragments and what separates them, see our article on the growth hormone lipolytic fragment.
Reading the AOD-9604 literature well requires holding two things apart. The first is the biological claim that a short C-terminal region of growth hormone carries lipolytic information — a claim with real in vitro support. The second is the therapeutic claim that this translates into meaningful change in a whole organism, which the human data did not bear out. Preclinical papers frequently cite the first as though it establishes the second. A laboratory using this peptide as a probe for adipocyte signalling is on defensible ground; one treating it as a validated metabolic intervention is not.
Forms and sizes we supply
| Attribute | Specification |
|---|---|
| Form | Lyophilized powder, sealed glass vial |
| Sizes | 5 mg, 10 mg |
| Purity | Greater than or equal to 99% by HPLC, lot-matched COA |
| CAS | 221231-10-3 |
| Molecular weight | 1815.08 Da |
| Formula | C78H123N23O23S2 |
| Residues | 16 (hGH 177-191 plus N-terminal Tyr) |
| Intended use | Laboratory research only |
Injectable vials are on the AOD-9604 product page; a sublingual format is listed as AOD-9604 troches. All sit within the fat-loss and metabolic peptides collection.
Format matters more for a small unmodified peptide than it does for the acylated incretins. A 1.8 kDa peptide with no albumin-binding chain is cleared quickly and is poorly absorbed across mucosal surfaces, which is why sublingual and oral formats of this molecule are best understood as delivery experiments rather than as equivalent alternatives to a reconstituted vial. If a study design depends on quantified exposure, the injectable lyophilized format is the only one where the amount entering the system can be calculated from first principles. Our note on oral and sublingual peptide formats explains why bioavailability is the limiting factor.
Reconstitution and storage in a lab context
The arithmetic is straightforward: a 5 mg vial reconstituted with 2 mL of bacteriostatic water gives 2.5 mg/mL, equal to 2,500 mcg/mL, so 0.1 mL of that solution contains 250 mcg of peptide. Small unmodified peptides like this one dissolve easily and tolerate handling better than acylated analogs, but the disulfide bridge is a liability worth respecting — reducing conditions, prolonged exposure to alkaline buffers, and trace thiols in a poorly chosen diluent can all open the loop.
Store sealed lyophilized powder at minus 20 degrees Celsius, protected from light and moisture; hold reconstituted solution at 2 to 8 degrees Celsius and use within the study window. Aliquot at reconstitution to avoid repeated freeze-thaw rounds. See our reconstitution guide.
Purity, COA and how to read it
A certificate should show an HPLC chromatogram with main-peak area percentage, mass spectrometry identity against the theoretical 1815.08 Da, net peptide content, lot number and analysis date. Two checks matter specifically here. First, disulfide state: an open-loop variant differs by only two mass units and a low-resolution spectrum will not resolve it, yet it is a different molecule pharmacologically. Second, identity versus the unmodified fragment — AOD-9604 and HGH Fragment 176-191 differ by roughly two daltons in our catalog figures, so a supplier substituting one for the other would not be caught by a purity percentage alone. Insist on a mass result with adequate resolution; see mass spectrometry identity.
Analytical detection is the last practical consideration. The added tyrosine gives AOD-9604 measurable absorbance at 280 nm, which the unmodified fragment essentially lacks, so a laboratory quantifying the peptide by UV can work at a wavelength with far less background interference than the 214 nm peptide-bond band. Buffer components, solvents and plastics all absorb strongly near 214 nm; almost nothing does at 280 nm. Where accurate quantification of recovered peptide matters — in stability studies, uptake experiments or any assay where the amount actually present must be measured rather than assumed — that single residue is a substantial methodological advantage.
Regulatory status
AOD-9604 is not an approved medicine in the United States or elsewhere. It has been reviewed in a food-ingredient context in some jurisdictions, which is sometimes misrepresented as therapeutic approval — it is not. Research-grade AOD-9604 is supplied as a laboratory reference chemical, labelled research use only, not approved or formulated for administration to humans or animals. It also appears on sports anti-doping prohibited lists. See research use only, explained.
Related peptides and comparisons
The direct comparison is AOD-9604 vs HGH Fragment 176-191, the unmodified parent fragment. Researchers working on growth-hormone-independent metabolic signalling often also look at 5-Amino-1MQ.