AOD-9604

What Is AOD-9604?

AOD-9604 is a synthetic peptide corresponding to a small section at the tail end of human growth hormone, specifically the region researchers believed was responsible for growth hormone's fat-metabolizing effects. It was developed in the 1990s by researchers at Monash University in Australia, with a tyrosine addition and other modifications designed to isolate that fat-related activity from growth hormone's other effects, including its influence on IGF-1 and blood sugar.

The name stands for Anti-Obesity Drug 9604, reflecting its original development purpose. It progressed unusually far for a compound in this space, through Phase I, II, and III human trials, before its pivotal efficacy trial came up short and the pharmaceutical program was discontinued.

What AOD-9604 Is Being Researched For

• Fat Metabolism in Animal Models

  Early research found that AOD-9604 reduced body weight gain in obese rats without the negative effects on insulin sensitivity typically seen with full-length growth hormone.^[1]

• Human Safety and Tolerability

  A published human study assessed the safety and tolerability of AOD-9604 across a range of doses, part of the broader clinical development program before it was discontinued.^[2]

• Why the Pharmaceutical Program Was Discontinued

  Despite the encouraging animal data and six completed human trials involving roughly 900 participants, the pivotal Phase IIb obesity trial did not meet its primary efficacy endpoint, and the sponsoring company ended development in 2007. This is an important and often underreported part of the AOD-9604 story.

How AOD-9604 Works

• Increasing Fat Breakdown

  Research points to AOD-9604 upregulating beta-3 adrenergic receptors in fat tissue, the primary receptor involved in triggering lipolysis, the breakdown of stored fat into usable fatty acids.^[1]

• Avoiding Growth Hormone's Other Effects

  Research points to AOD-9604 not activating the growth hormone receptor or raising IGF-1 levels the way full-length growth hormone does, which was the specific design goal behind isolating this fragment in the first place.^[1]

• A Mechanism That Didn't Translate to Clinical Success

  Research points to an important gap between AOD-9604's preclinical mechanism and its clinical outcome. The animal data supporting a distinct, receptor-independent fat-metabolizing effect was consistent, but that mechanistic promise did not translate into a statistically significant weight-loss result in the pivotal human trial.

Reconstitution and Handling

AOD-9604 is typically supplied as a lyophilized powder in a sealed vial and reconstituted with bacteriostatic water before use in a research setting. Water should be added slowly rather than injected directly into the powder, and the vial should be swirled, not shaken.

Since the amount of water used affects the concentration of the final solution, researchers often use a dosage calculator to work this out before mixing. Once reconstituted, the solution is kept refrigerated to help preserve its stability.

Key Takeaways

AOD-9604 stands out for having gone further through the human clinical trial process than almost any other compound on this site, yet still falling short: the pivotal Phase IIb obesity trial failed its primary endpoint, and development was discontinued in 2007. Its mechanism, isolating growth hormone's fat-metabolizing activity from its other effects, held up well in preclinical models but did not translate into a successful clinical outcome. That gap between mechanistic promise and clinical result is the central, honest takeaway of the AOD-9604 research record.

Frequently Asked Questions

Sources and Research

1. Ng FM, Sun J, Sharma L, Libinaka R, Jiang WJ, Gianello R. Metabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone. Horm Res. 2000;53(6):274-278.
2. Stier H, Vos E, Kenley D. Safety and tolerability of the hexadecapeptide AOD9604 in humans. J Endocrinol Metab. 2013;3(1-2):7-15.