Synthetic analog of the growth-hormone 176–191 lipolytic region — developed by Metabolic Pharmaceuticals and the version advanced into human trials. A distinct compound from HGH Fragment 176–191, not an alias.
Last Updated: August 2026
AOD-9604 is a synthetic peptide based on the C-terminal lipolytic region of human growth hormone, developed by Metabolic Pharmaceuticals (Australia) as a candidate anti-obesity drug. It is the version of the GH lipolytic fragment that was actually carried into human clinical trials. It is not approved for any therapeutic indication and is sold as a research-use-only compound. AOD-9604 is catalogued as a chemically distinct compound from the unmodified HGH Fragment 176–191 — a different CAS number (221231-10-3 vs 66004-57-7), a different PubChem record, and a molecular mass of roughly 1815 Da versus the fragment's ~1799 Da. It is commonly referred to as the tyrosine-modified, or "Tyr-hGH," form of the fragment.
AOD-9604 is a synthetic analog of the growth-hormone 176–191 lipolytic domain, catalogued separately from the unmodified HGH Fragment 176–191 and commonly described as its tyrosine-modified form. The two are closely related and target the same region of growth hormone, but they are listed as distinct molecules. AOD-9604 (CAS 221231-10-3) is Tyr-hGH(177–191), the 177–191 fragment carrying an added N-terminal tyrosine and an intramolecular disulfide bond. Published molecular-weight values for the pair are reported inconsistently across vendor and reference sources, so sequence and CAS number — not a quoted mass — are the reliable way to tell them apart. The native, unmodified fragment is HGH Fragment 176–191 (CAS 66004-57-7). The practical distinction that matters most: AOD-9604 is the analog that advanced into human clinical development; the unmodified fragment did not. Evidence level: Structural/analytical (distinct catalogued compounds).
AOD-9604 mimics the fat-metabolism-regulating region of growth hormone — stimulating lipolysis (fat breakdown) and inhibiting lipogenesis (fat storage) in fat cells — without engaging the growth hormone receptor. Because it does not act on the GH receptor, it is not expected to raise IGF-1 or drive the insulin antagonism and tissue-proliferation associated with full-length GH; isolating that fat-loss signal from GH's other effects was the original rationale for the molecule. Evidence level: Preclinical (rodent and in vitro lipolysis).
AOD-9604 AOD-9604 carries a real human clinical record: across six randomized, double-blind, placebo-controlled trials (about 893 participants) run by Metabolic Pharmaceuticals in the 2000s, it was well tolerated — with a safety and tolerability profile indistinguishable from placebo and no rise in IGF-1. What it could not do was work well enough to become a drug: the pivotal 24-week Phase 2b obesity trial missed its primary weight-loss endpoint versus placebo, and Metabolic Pharmaceuticals discontinued obesity development in 2007. AOD-9604 has not advanced in any obesity program since., and the obesity program was discontinued. Reported safety in those trials was generally favorable, with mild side effects. After the drug program ended, the compound was repositioned outside the obesity-pharmaceutical pathway. Evidence level: Phase 2b human data (efficacy below development threshold).
AOD-9604 works through direct fat-cell lipolysis — a fundamentally different mechanism from GLP-1-class drugs, which act through appetite suppression and broader metabolic regulation — and the human evidence points to far smaller effects than the GLP-1 and multi-agonist compounds produce.
| Compound | Mechanism | Weight-loss effect | Clinical development |
|---|---|---|---|
| Retatrutide | GLP-1 + GIP + glucagon | ~24% — Phase 2 | Active |
| Tirzepatide | GLP-1 + GIP (dual) | 22.5% — Phase 3 | FDA-approved |
| Semaglutide | GLP-1 receptor agonist | ~15% — Phase 3 | FDA-approved |
| AOD-9604 | Direct adipocyte lipolysis | Below efficacy threshold in Phase 2b | Abandoned as obesity drug |
AOD-9604 is not approved as a therapeutic drug for any indication. It is also not eligible for pharmacy compounding: AOD-9604 is not on the FDA's 503A list of bulk drug substances permitted for compounding, and the FDA's Pharmacy Compounding Advisory Committee voted against including it at its December 4, 2024 meeting. In sport, AOD-9604 is prohibited at all times by the World Anti-Doping Agency as a growth-hormone fragment under Section S2.2.3 of the Prohibited List. After the obesity program ended it appeared in non-pharmaceutical contexts — including supplement and cosmetic formulations in some jurisdictions — but it holds no approved medical indication and is sold to researchers as a research-use-only material. Regulatory treatment varies by country. Context in are peptides legal — regulatory status by country. Evidence level: Regulatory/market (no approved therapeutic indication).
AOD-9604 and HGH Fragment 176–191 are closely related and elute similarly, so a standard HPLC purity certificate cannot confirm which of the two molecules is actually in a vial — it reports purity against whatever name the submitter wrote, not the molecule's identity. A product sold as AOD-9604 could be the cheaper unmodified fragment, and an HPLC-only COA would not catch the substitution. Mass spectrometry, which resolves the mass difference between them, is the meaningful identity check. Evidence level: Analytical (method limitation).
Peptigrity collects independent third-party Certificates of Analysis for AOD-9604 from shops' official channels and verifies each for authenticity before publishing. Because shops choose which COAs to publish, results reflect the batches shops have made public rather than every production batch — a selection bias we state openly. A community-funded Testing Grant to purchase and test vials anonymously is in development. Tests in the database come from independent labs such as Janoshik Analytical, Freedom Diagnostics, and Chromate.
No. They are closely related but catalogued as distinct compounds, with different CAS numbers and molecular masses. AOD-9604 is commonly described as the tyrosine-modified ("Tyr-hGH") form of the 176–191 fragment and is the version that reached Phase 2b human trials. Some vendors use the names interchangeably, but the distinction is real and matters for buyers expecting one specific molecule. See HGH Fragment 176–191.
In human trials reaching Phase 2b, AOD-9604 did not show weight-loss efficacy sufficient to support development as an obesity drug, and the program was discontinued. Preclinical data shows lipolytic activity, but human results were weak. GLP-1-class compounds produce substantially larger weight-loss effects.
AOD-9604 is generally available as a research-use-only chemical in most jurisdictions but is not approved for human therapeutic use. Regulatory treatment varies by country. Full breakdown in the peptide legal status guide.
Look for an independent third-party HPLC certificate of analysis from a lab the vendor does not own or pay — and for AOD-9604 specifically, mass spectrometry identity confirmation, because an HPLC purity test alone cannot distinguish AOD-9604 from the closely related HGH Fragment 176–191. COA interpretation in red flags in peptide certificates of analysis.
No. AOD-9604 is not approved for human consumption, and Peptigrity is an independent review platform, not a medical authority. Anyone considering use should consult a licensed physician.
This section is for educational and informational purposes only and does not constitute medical advice. AOD-9604 is not approved by the FDA or any other regulator for human therapeutic use. Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.
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