A 16-amino-acid modified fragment of human growth hormone (residues 176-191) designed to retain GH's fat-burning properties while eliminating its growth-promoting and diabetogenic effects. Also studied for osteoarthritis and cartilage repair.
AOD-9604 (Advanced Obesity Drug) is a modified 16-amino-acid fragment corresponding to residues 176-191 of human growth hormone (hGH), with a tyrosine residue added at the C-terminus. It was developed by Metabolic Pharmaceuticals in Australia based on the observation that the C-terminal portion of GH is responsible for its lipolytic (fat-burning) effects, while the N-terminal portion mediates growth and IGF-1 stimulation.
The key innovation of AOD-9604 is that it mimics GH's fat-burning activity without increasing IGF-1 levels, without promoting bone/muscle growth, and without the diabetogenic effects (insulin resistance) associated with full-length GH therapy. This makes it potentially safer for long-term anti-obesity use.
AOD-9604 acts on adipose tissue through a mechanism independent of the growth hormone receptor. It appears to activate beta-3 adrenergic signaling in fat cells, stimulating hormone-sensitive lipase (HSL) to break down stored triglycerides into free fatty acids and glycerol. Simultaneously, it inhibits fatty acid synthase, reducing new fat formation. This dual action — increased fat burning + decreased fat storage — produces a net reduction in adipose tissue.
| Pathway | Effect | Significance |
|---|---|---|
| Lipolysis stimulation | Activates HSL in adipose tissue via β3 pathways | Breaks down stored fat into free fatty acids for energy |
| Lipogenesis inhibition | Reduces fatty acid synthase activity | Prevents new fat accumulation |
| Cartilage repair | Stimulates proteoglycan and type II collagen synthesis in chondrocytes | Potential OA therapy — TGA approved in Australia for this indication |
| No IGF-1 increase | Does not bind GH receptor or stimulate hepatic IGF-1 | Avoids cancer risk and growth effects associated with GH therapy |
| No glucose effects | Does not impair insulin sensitivity | Safer metabolic profile than full-length GH |
| Study | Design | Findings | Level |
|---|---|---|---|
| Phase IIb obesity | RCT, n=300, 12 weeks | Modest but significant weight loss vs placebo. Did not meet primary endpoint for regulatory approval. | Level I-II (modest) |
| Cartilage repair | Preclinical + Phase II | Stimulated proteoglycan synthesis in animal OA models. Phase II human trials showed cartilage protection. | Level II |
| Safety/tolerability | Multiple human studies | No significant adverse effects. No changes in IGF-1, glucose, or insulin levels. | Level II |
| GRAS determination | FDA review | AOD-9604 received GRAS (Generally Recognized as Safe) status as a food ingredient in the US (2014) | Regulatory |
Generally well-tolerated: No significant adverse effects in human trials at standard doses.
Modest efficacy: The Phase IIb trial showed statistical but not clinically impressive weight loss, which is why Metabolic Pharmaceuticals pivoted to OA.
Quality concerns: As a research peptide, purity varies. Not manufactured under pharmaceutical-grade conditions for consumer use.
| Jurisdiction | Status |
|---|---|
| FDA | Not approved as a drug. Has GRAS status as a food ingredient (2014). |
| TGA (Australia) | Approved for intra-articular injection for knee osteoarthritis (2023) |
| WADA | Banned under S0 (non-approved substances) |