AOD-9604

AOD-9604 is a synthetic peptide hormone fragment corresponding to the C-terminal region of human growth hormone (hGH 176-191) with an additional N-terminal tyrosine residue. It was designed to mimic the fat-mobilising action of hGH without triggering its growth-promoting or diabetogenic effects - that is, without measurable IGF-1 elevation and without impairing glucose metabolism. The pivotal human study, a randomised Phase 2b trial in 536 obese subjects over 24 weeks, missed its primary efficacy endpoint, and Metabolic Pharmaceuticals discontinued the anti-obesity programme in March 2007.

What is AOD-9604?

AOD-9604 (Anti-Obesity Drug 9604) is a 16-amino-acid modified hexadecapeptide with the sequence Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe and a molecular weight of about 1,815 Da. It corresponds to the C-terminal fragment 176-191 of human growth hormone plus an extra N-terminal tyrosine, intended to improve stability. It was developed by Metabolic Pharmaceuticals in Australia, originally as an oral anti-obesity drug candidate.

How does AOD-9604 work?

Unlike full-length hGH, AOD-9604 does not bind to the classical GH receptor and therefore does not raise IGF-1 to a clinically meaningful degree. Preclinical findings point to the following mechanisms in adipose tissue:

• Stimulation of lipolysis and inhibition of lipogenesis via β3-adrenergic signalling.
• Increased fat oxidation with chronic dosing.
• Reduced weight gain in genetically obese mouse models (ob/ob, Zucker rats) without the insulin resistance typical of hGH.

In β3-AR knockout mice, the long-term lipolytic effect was blunted, supporting the involvement of the β3-adrenergic pathway (Heffernan et al., Endocrinology 2001).

AOD-9604 vs hGH Fragment 176-191

AOD-9604 is not identical to native hGH fragment 176-191 - it is a pharmaceutically optimised variant. The single key difference: AOD-9604 carries an extra N-terminal tyrosine in place of the native phenylalanine, designed to improve stability. Both sequences are often discussed interchangeably in the literature, but they are biochemically distinguishable.

Clinical evidence

1. Phase 2a (12 weeks, 1 mg/day orally): 2.6 kg weight loss vs 0.8 kg on placebo - a modest but statistically positive signal.
2. Phase 2b OPTIONS (24 weeks, 536 obese subjects, 0.25/0.5/1 mg per day orally): primary endpoint not met. Metabolic Pharmaceuticals discontinued the anti-obesity programme in March 2007.
3. Safety synthesis (Stier et al., 2013, six RCTs): 0.25-1 mg per day for up to 24 weeks were well tolerated, with no immunogenicity, no adverse effects on glucose metabolism, and no IGF-1 rise.

The OPTIONS Phase 2b data were never published in a primary peer-reviewed paper. The negative outcome is documented through the Misra review (Obesity Pharmacotherapy, 2013, PMC3584306) and Metabolic Pharmaceuticals disclosures.

Recent developments (2024-2026)

• FDA status (December 2024): AOD-9604 was classified as a Category 2 bulk drug substance - physician compounding is not permitted for now.
• GRAS status (2014): The FDA confirmed "Generally Recognized As Safe" as a food/supplement ingredient at doses up to 1 mg per day. This is not a therapeutic approval.
• TGA Australia (2014): Scheduled together with GH secretagogues under Schedule 4; medical prescription required.
• WADA: Listed under S0 (Non-Approved Substances) - prohibited in sport.

AOD-9604 in cartilage research

Independent of the obesity indication, preclinical data suggest a chondroprotective effect: in a collagenase-induced knee OA model in rabbits, intra-articular AOD-9604 - alone and combined with hyaluronic acid - improved cartilage regeneration parameters and reduced lameness duration. A review of peptide-based therapies for osteoarthritis lists AOD-9604 among compounds that consistently improve cartilage markers in animal models (PMC11556548). No controlled human cartilage trial has been published.

FAQ

Is AOD-9604 approved?

No. AOD-9604 has no therapeutic approval anywhere in the world. It only holds GRAS status as a food/supplement ingredient in the US (max. 1 mg/day orally) and is prescription-only in Australia.

Does AOD-9604 work in humans?

The largest controlled human study (Phase 2b, 536 subjects, 24 weeks) did not show statistically significant weight loss versus placebo. The smaller Phase 2a data were positive but were not confirmed in the better-powered follow-up trial.

Which peptides are clinically successful for obesity?

Unlike AOD-9604, modern incretin mimetics have cleared the clinical bar: tirzepatide (dual GLP-1/GIP agonist) and retatrutide (triple GLP-1/GIP/glucagon agonist) achieved over 20 % and up to 28 % weight loss respectively in Phase 3. For broader context see the coverage of the GLP-1 wave reshaping grocery markets.

Why is AOD-9604 often mentioned alongside CJC-1295 / Ipamorelin?

AOD-9604 belongs - like CJC-1295 / Ipamorelin - to the family of hGH fragments and GH secretagogues. While CJC/Ipamorelin boost endogenous GH release, AOD-9604 selectively mimics the lipolytic component of hGH without activating the IGF-1 axis.

This entry is for information only and is not medical advice. It is not a dosing or sourcing recommendation.