Questions
AOD-9604, questioned.
Twenty-two questions, answered from the published record. Direct. Cited. No dosing guidance.
What does the peptide AOD9604 do?
In fat cells it slows the synthesis of new fat (antilipogenic) and, in animals, shifts metabolism toward fat oxidation, partly by raising beta-3 adrenergic receptor expression. After 14 days of chronic dosing it reduced body weight and fat in obese mice; the long-term effect required functional beta-3 adrenergic signalling [4]. In people, it did not produce significant weight loss [10].
How does AOD9604 stimulate lipolysis without affecting the HGH receptor?
It is a C-terminal fragment of growth hormone, not the whole hormone, so it does not bind the growth hormone receptor or raise IGF-1 [1]. Its fat effects work downstream in the adipocyte — inhibiting acetyl-CoA carboxylase to cut fat synthesis [2] and up-regulating the beta-3 adrenergic receptor in obese-mouse fat [4] — separate from growth-hormone-receptor signalling.
Is AOD9604 a steroid?
No. AOD-9604 is a peptide — a 16-amino-acid fragment of human growth hormone [3]. Steroids are lipid molecules built on a four-ring carbon skeleton and act through nuclear hormone receptors. AOD-9604 shares neither the structure nor the mechanism, and it does not engage the growth hormone receptor [1].
What is AOD-9604?
AOD-9604 ("Anti-Obesity Drug 9604") is a synthetic 16-amino-acid peptide modelled on the C-terminal lipolytic region of human growth hormone, residues 177-191, with an added N-terminal tyrosine [3]. It was developed as an oral anti-obesity drug. It is investigational, not FDA-approved, and its pivotal human weight-loss trial failed [9].
Does AOD-9604 actually work?
For weight loss in humans, the evidence says no. Across roughly six trials in about 900 obese adults, it was as safe as placebo but the pivotal Phase IIb trial showed no statistically significant weight loss versus placebo, and the program was discontinued [5][9]. The fat-metabolism mechanism is real in rodents; it did not translate to a human benefit.
How does AOD-9604 work?
It targets fat-cell metabolism. It inhibits acetyl-CoA carboxylase to reduce new fat synthesis [2] and up-regulates the beta-3 adrenergic receptor, raising fat oxidation in obese mice [4]. It does this without binding the growth hormone receptor, so it does not raise IGF-1 [1]. The foundational activity is antilipogenic rather than directly lipolytic [3].
Is AOD-9604 FDA approved?
No. AOD-9604 is not FDA-approved for any indication. The Metabolic Pharmaceuticals anti-obesity program was discontinued after the pivotal Phase IIb trial failed to meet its primary endpoint [9]. It was reviewed by the FDA Pharmacy Compounding Advisory Committee in December 2024 (docket FDA-2024-N-4777); current 503A compounding status should be verified independently.
Is AOD-9604 safe?
In trials, its safety and tolerability were indistinguishable from placebo across roughly six studies totalling about 900 obese subjects, without the adverse effects of full-length hGH [5]. But it is not approved, long-term human data is limited to about 24 weeks, and gray-market product quality is unverified [9]. "Tolerated in trials" is not the same as "safe for unsupervised use."
Does AOD9604 raise IGF-1 like HGH?
No. AOD-9604 does not bind the growth hormone receptor, so it does not raise circulating IGF-1 — the receptor-sparing design is the whole point of the molecule [1]. Non-clinical evaluation also found it free of genotoxic and toxicological concerns after chronic oral dosing in rats and primates [7].
Why was AOD-9604 discontinued as a pharmaceutical drug?
Because it did not work for its intended use. The pivotal Phase IIb obesity trial did not show statistically significant weight loss versus placebo, so Metabolic Pharmaceuticals discontinued the obesity development program around 2007 and the compound was never approved [9]. Strong rodent fat-metabolism data simply did not translate into clinical efficacy [11].
What is the half-life of AOD9604?
Short — approximately 3 minutes after intravenous injection in a pig pharmacokinetic model. The intact peptide is cleared rapidly, degrading by sequential removal of amino acids from the N-terminus in a cascade [7]. That rapid clearance is one reason the human program dosed orally and frequently rather than relying on a long systemic half-life.
Is AOD9604 orally bioavailable or does it have to be injected?
Oral absorption was demonstrated, and oral tablets were the primary route in the Metabolic Pharmaceuticals human obesity program [5]. Non-clinical work supported oral dosing in rats and primates [7]. Intravenous, intra-articular, and intraperitoneal routes were used in other studies; subcutaneous human pharmacokinetics have not been published.
Does AOD9604 work by activating beta-3 adrenergic receptors?
Partly. In obese mice, chronic treatment up-regulated beta-3 adrenergic receptor expression, and the long-term weight and lipolytic response required functional beta-3 AR — in knockout mice it was abolished. The acute rise in energy expenditure and fat oxidation, however, persisted without it [4]. So beta-3 AR signalling carries the chronic effect, not the acute one.
Does AOD9604 affect insulin or blood sugar levels?
AOD-9604 was designed to avoid the glucose-disrupting activity of growth hormone. Mapping studies showed that C-terminal fragments containing residues 178-191 carry the diabetogenic/insulin-modulating activity [13]; the lipolytic-fragment design steers clear of it. Non-clinical evaluation found no major toxicological concerns after chronic dosing [7].
What are the side effects of AOD9604?
In trials, side effects were hard to distinguish from placebo across roughly six studies in about 900 subjects [5]. Community reports mention occasional injection-site redness and, more often, simply no noticeable effect. There is no long-term human safety surveillance beyond about 24 weeks, so rare or chronic effects remain uncharacterised [9].
Is AOD9604 banned in competitive sports?
Yes. As a growth-hormone fragment, AOD-9604 falls under the WADA Prohibited List, Section S2 (peptide hormones, growth factors, and related substances), and is prohibited at all times in sport [6]. Dedicated anti-doping assays can detect it even though it does not interfere with the standard hGH isoform immunoassay. Athletes should treat it as a prohibited substance regardless of vendor claims.
What happened in the AOD9604 Phase IIb clinical trial?
The pivotal Phase IIb obesity trial did not demonstrate statistically significant weight loss versus placebo. Despite a tolerability profile indistinguishable from placebo across the broader program [5], the missed efficacy endpoint led Metabolic Pharmaceuticals to discontinue the obesity development program around 2007, and the compound was never approved for any indication [9].
How much weight can you lose on AOD9604 peptide?
The human evidence does not support a weight-loss figure. The pivotal Phase IIb trial showed no statistically significant weight loss versus placebo, and the program was discontinued [9]. Community members who report any change almost always credit a concurrent calorie deficit and exercise, which makes the peptide impossible to single out. No reliable human weight-loss number exists.
Does AOD9604 help with cartilage repair and osteoarthritis?
Only in animals so far. In a collagenase-induced knee osteoarthritis model in 32 rabbits, weekly intra-articular injection of 0.25 mg AOD-9604 (with or without 6 mg hyaluronic acid) for 4-7 weeks reduced cartilage-degeneration scores versus saline [14]. There are no published human osteoarthritis trials of AOD-9604 itself, so this is a preclinical finding, not a treatment.
Does AOD9604 preserve muscle mass while reducing fat?
There is no human evidence for muscle preservation, because there is no demonstrated human fat-loss effect to pair it with — the pivotal obesity trial failed [9]. Community reports generally describe no change in strength, recovery, or muscle, consistent with a molecule that does not engage the growth hormone receptor [1]. Claims of muscle-sparing fat loss are not supported by trials.
What is the mechanism of action of AOD9604?
AOD-9604 reproduces the fat-metabolism activity of growth hormone's C-terminal domain while sparing the GH receptor. It inhibits acetyl-CoA carboxylase to cut new fat synthesis [2], up-regulates the beta-3 adrenergic receptor in obese-mouse fat [4], and increases fat oxidation — without binding the GH receptor or raising IGF-1 [1]. The earliest characterised activity is antilipogenic, not directly lipolytic [3].
Where do you inject AOD-9604?
This site gives no human dosing or administration instructions. For the record, the studied routes were oral tablets (the human obesity program) [5], intravenous (human and animal PK) [7], intra-articular into a joint (rabbit osteoarthritis) [14], and intraperitoneal (mouse studies) [4]. Subcutaneous human pharmacokinetics have not been published, so common community assumptions about a subcutaneous route are not backed by peer-reviewed data.