Educational reference, not medical advice. This page summarizes information from published research and regulatory filings for educational purposes. It is not a recommendation to use any compound and should not replace guidance from a licensed healthcare provider. Most peptides discussed here are not approved for the uses described.
What it is
AOD-9604 — "Anti-Obesity Drug 9604" — is a 16-amino-acid synthetic peptide corresponding to the C-terminal region (residues 176–191) of human growth hormone, with a tyrosine added at the N-terminus to support stability. The fragment was identified in the 1990s by researchers at Monash University in Melbourne after work in the prior decade suggested that the lipolytic effects of growth hormone could be separated from its other actions (insulin-like growth factor 1 stimulation, insulin resistance, cell proliferation) by isolating specific subsequences.
The peptide was advanced into the clinic by Metabolic Pharmaceuticals, an Australian biotech later acquired by Calzada.
History
Preclinical work in obese mice (Heffernan et al., Endocrinology 2001) reported that AOD-9604 reduced body weight gain and fat mass without raising serum insulin-like growth factor 1 — a result consistent with the hypothesis that the lipolytic effects of growth hormone could be separated from its growth-promoting effects.
Metabolic Pharmaceuticals then ran a series of human trials. Early Phase I and Phase IIa results in 2002–2004 suggested modest fat-loss effects in obese adults. The pivotal Phase IIb trial in 2006–2007 randomized 502 adults with obesity to placebo or one of four AOD-9604 doses (1, 5, 10, or 30 mg daily) over 24 weeks. The trial did not meet its primary efficacy endpoint: the difference in weight loss between AOD-9604 and placebo was small and not statistically meaningful. Metabolic Pharmaceuticals subsequently discontinued the obesity program.
After the obesity program ended the molecule was repurposed for other indications, including osteoarthritis, and in 2014 it received Generally Recognized as Safe (GRAS) status from an independent panel for use in foods — a regulatory classification distinct from drug approval.
Regulatory status
AOD-9604 has no drug approval in the United States, the European Union, Australia, or any other major market. In November 2023, the FDA placed AOD-9604 in Category 2 of the 503A bulk substances list — the category for substances that "raise significant safety risks" — which effectively bars compounding pharmacies in the United States from preparing it for patients. It is also on the World Anti-Doping Agency's prohibited list under the S2 (peptide hormones, growth factors) category.
The GRAS status for food use does not authorize injection or therapeutic claims.
Mechanism
The published mechanism papers describe AOD-9604 as a lipolytic peptide that stimulates fat breakdown without activating the growth hormone receptor in the classical way. The proposed mechanism is selective activation of the beta-3 adrenergic receptor pathway in adipocytes, with consequent increases in lipolysis and fat oxidation.
The 2001 Heffernan study tested this in beta-3 adrenergic receptor knockout mice and found that AOD-9604's effects on lipid metabolism were partially attenuated, supporting the proposed mechanism. However, no human study has clearly demonstrated a meaningful lipolytic effect at the doses tested, and the Phase IIb failure suggests the mouse-to-human translation was incomplete.
Half-life and dosing intervals
The published terminal half-life is short — 30 to 40 minutes after subcutaneous injection in humans. Despite this short half-life, the clinical trials used once-daily subcutaneous dosing on the hypothesis that pulsatile receptor activation would be sufficient to drive lipolysis.
In the Phase IIb trial, the four doses tested were 1, 5, 10, and 30 mg administered as a single daily subcutaneous injection. No dose produced a statistically significant benefit on the primary weight-loss endpoint.
There is no established outside-of-trial dose. The doses described in online observational use (typically 250–500 mcg once or twice daily) are an order of magnitude lower than any Phase IIb dose and are not supported by the clinical data.
Reconstitution example
Research-grade AOD-9604 is typically supplied lyophilized in 2 mg or 5 mg vials.
A 5 mg vial reconstituted with 2 mL of bacteriostatic water yields 2.5 mg/mL. On a 1 mL U-100 insulin syringe, 10 units (0.1 mL) contains 250 mcg. Vial's calculator handles the unit-to-mg conversion automatically.
What to know
- Failed its pivotal trial. The Phase IIb obesity trial did not meet its primary endpoint, and Metabolic Pharmaceuticals discontinued the obesity program after the result.
- Not approved. Compounding pharmacies in the United States cannot legally prepare AOD-9604 for patients, and it is banned in competitive sport.
- Short half-life. The 30 to 40 minute circulating half-life means subcutaneous injection produces only a brief receptor exposure relative to once-daily dosing.
- GRAS for food is not drug approval. Marketing materials sometimes describe AOD-9604 as "FDA approved" or "GRAS approved"; neither is an authorization for therapeutic use.
- Storage. Lyophilized peptide is best stored refrigerated and protected from light. Once reconstituted, refrigerate and use within the stability window specified by the supplier.
Sources
- 1.Heffernan M et al. (2001). The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism following chronic treatment in obese mice and beta(3)-AR knock-out mice. Endocrinology.
- 2.Wilding J. (2004). AOD-9604 (Metabolic). Current Opinion in Investigational Drugs.
- 3.Halford JC. (2006). Obesity drugs in clinical development. Current Opinion in Investigational Drugs.
- 4.FDA 503A Bulk Drug Substances list — Category 2 (November 2023).