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Encyclopedia · Metabolic & Weight Loss

AOD-9604

AOD-9604 is a synthetic 16-amino-acid peptide fragment derived from the C-terminal region of human growth hormone, often written in the literature as Tyr-hGH177-191. [2] It was designed to isolate growth hormone's fat-metabolism effects from its broader growth-promoting and glucose-related actions, with the goal of finding an obesity treatment without the risks associated with full growth hormone therapy. The compound is also written as AOD9604 or AOD 9604 in different sources, and appears in both a free-base and an acetate salt form in regulatory documents. It is not equivalent to, or a safer substitute for, approved growth hormone products such as somatropin, which have their own distinct FDA-approved indications and warnings.

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What It Is

AOD-9604 is a synthetic 16-amino-acid peptide fragment derived from the C-terminal region of human growth hormone, often written in the literature as Tyr-hGH177-191.[2] It was designed to isolate growth hormone's fat-metabolism effects from its broader growth-promoting and glucose-related actions, with the goal of finding an obesity treatment without the risks associated with full growth hormone therapy.

The compound is also written as AOD9604 or AOD 9604 in different sources, and appears in both a free-base and an acetate salt form in regulatory documents. It is not equivalent to, or a safer substitute for, approved growth hormone products such as somatropin, which have their own distinct FDA-approved indications and warnings.

How It Works

AOD-9604 is proposed to act on lipid metabolism through pathways related to lipolysis (fat breakdown), lipogenesis (fat formation), and fat oxidation, but its exact receptor-level mechanism has not been settled.[4] Researchers designed it around the idea that the C-terminal portion of growth hormone contains a distinct lipid-mobilizing domain, separate from the receptor-binding region responsible for growth and glucose effects.

In rodent studies, AOD-9604 was associated with increased fat breakdown and fat oxidation, and reduced fat formation, without reproducing the blood-sugar-raising effects seen with full growth hormone in the same models. Human trials monitored IGF-1 levels and found no clinically meaningful increase, and mechanistic work suggested AOD-9604 does not compete with growth hormone for its receptor — though this receptor question remains only partly resolved.[2]

What the Research Shows

AOD-9604's human evidence is more extensive than most research peptides, but ultimately disappointing for its intended use. Six randomized, placebo-controlled trials involving 893 adults evaluated intravenous and oral dosing, and a 12-week study using 1 mg/day reportedly showed modestly greater weight loss than placebo in early summaries.[2]

However, the pivotal 24-week OPTIONS study, which enrolled more than 500 adults with obesity under a formal diet-and-exercise program, did not show a statistically significant weight-loss difference versus placebo at its primary endpoint. FDA reviewers concluded in 2024 that the available data did not support AOD-9604's effectiveness for obesity by any route of administration.[1] Broader online claims about muscle preservation, anti-aging, or performance benefits are not supported by controlled human trials.

Safety & Side Effects

Study authors generally described AOD-9604's side-effect profile as similar to placebo, with headache and mild digestive symptoms the most common complaints, and one severe chest-tightness event and one diarrhea event judged possibly related to the drug in separate trials.[2] No anti-AOD-9604 antibodies were detected in tested subjects, and IGF-1 and glucose tolerance did not shift meaningfully in trial settings.

Despite this, FDA reviewers reached a more cautious conclusion, citing serious adverse events reported elsewhere (including diarrhea, chest tightness, and cancers) that could not be assessed for causality due to incomplete information, and flagging real concerns for compounded products:

  • Immunogenicity risk from peptide aggregation or impurities
  • No human safety data at all for subcutaneous or transdermal routes, the forms most often sold as "research peptides"
  • Limited pharmacokinetic and bioavailability characterization overall[1]

Regulatory Status

AOD-9604 has no FDA-approved therapeutic indication, prescribing label, or approved dosage. A 2024 FDA Pharmacy Compounding Advisory Committee review evaluated AOD-9604 free base and acetate for inclusion on the 503A bulk compounding list and weighed against adding them, concluding the evidence did not support their effectiveness or the safety information needed for compounding.[1] FDA's current compounding-risk page lists AOD-9604 among substances that may pose significant safety risks.[11]

Some AOD-9604 literature references a Generally Recognized as Safe (GRAS) conclusion for food or supplement contexts, but GRAS status for an ingredient is unrelated to, and should never be confused with, FDA approval of a prescription drug. For athletes, WADA's Prohibited List explicitly names growth hormone fragments including AOD-9604 as banned substances.[15]