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AOD-9604

Also known as hGH fragment 176-191, AOD9604, Tyr-hGH(177-191)

Growth hormone fragment said to stimulate lipolysis, but human studies showed no weight loss.

early-clinical Metabolic & weight research chemical

At a glance

Category
Metabolic & weight
Status
research chemical
Route
subcutaneous (research use); studied orally in clinical trials
Half-life
short; in human pharmacokinetic studies on the order of tens of minutes after intravenous administration
Onset
not established; no consistent effect on body composition has been demonstrated in human studies
Molecular weight
approximately 1817 g/mol
Sequence
YLRIVQCRSVEGSCGF (tyrosine-modified C-terminal fragment of human growth hormone, residues 177-191)

Not approved as a medicine in the EU or US. Clinical development for obesity was discontinued after the primary endpoint was missed in phase 2b. It is described by vendors as having a status as an ingredient in certain US dietary supplement and cosmetic applications; we could not verify that against an FDA record and it should not be read as an FDA authorisation. As an injectable it is sold as a 'research chemical'. On the doping side the position is unambiguous: AOD-9604 is named in the WADA Prohibited List by name, under S2.2.3, "Growth hormone (GH), its analogues and fragments", in the line "growth hormone fragments, e.g. AOD-9604 and hGH 176-191" 4. It is not an S0 substance - S0 covers only substances "not addressed by any of the subsequent sections of the List", and this one is addressed in S2 4.

Doping status: Prohibited at all times under S2.2.3, where AOD-9604 is named by name as a growth hormone fragment. Substances in class S2 are non-Specified Substances.

Checked against the WADA 2026 Prohibited List. For a specific product and country, Global DRO is the lookup athletes are expected to use — the List names substances, not brand names.

Mechanism of action

AOD-9604 is a synthetic fragment corresponding to amino acids 177-191 of human growth hormone, with an additional tyrosine at the N-terminus. This part of the growth hormone molecule was identified in the 1990s as the region thought to be responsible for the lipolytic action, separate from the growth-promoting action.

Animal studies described the fragment as stimulating fatty acid breakdown in adipose tissue and inhibiting lipogenesis, presumably via an effect on the beta-3 adrenergic receptor. Studies in beta-3 adrenoceptor knock-out mice suggested, however, that the effect is not entirely dependent on this receptor 2; the precise target has never been elucidated.

Unlike full-length growth hormone, AOD-9604 does not bind to the growth hormone receptor and does not raise IGF-1 levels. That removes both the anabolic effect and the risk of insulin resistance — but also much of the plausible mechanism of action. The fragment is moreover degraded rapidly, which raises the question of how a clinically relevant effect would come about.

What the research shows

The evidence is weak. Preclinical research from a single research group in the 1990s and early 2000s described lipolytic effects in rodents, but the clinical development programme did not reach its endpoint and was discontinued. There is no convincing human evidence for weight loss.

Research in humans

Human studies were conducted by the developer Metabolic Pharmaceuticals. A 12-week randomised study with oral administration reported a mean weight loss of approximately 2.6 kg versus 0.8 kg with placebo. A subsequent larger phase 2b study, however, failed to meet its primary endpoint, after which development for obesity was discontinued. Safety and tolerability in these studies were comparable to placebo. There are no published, independently conducted studies of subcutaneous AOD-9604 for fat loss in humans.

Animal and lab research

The core studies are those of Ng et al. (Hormone Research, 2000), in obese Zucker rats 1, and Heffernan et al. (Endocrinology, 2001), in obese mice and beta-3 adrenoceptor knock-out mice 2, which described a decrease in fat mass and an increase in fatty acid oxidation. Both come from the same line of research and have not been independently replicated. The doses and routes of administration in these models do not translate straightforwardly to humans.

Caveats. Virtually all positive data come from a single commercial developer and are partly unpublished in peer-reviewed form. The definitive phase 2b result was negative. The compound is now promoted on the basis of preclinical findings while the human evidence is in fact disappointing — an important point when assessing claims. The short half-life has never been satisfactorily reconciled with the presumed prolonged action.

What it is used for

  • Historically studied for obesity and fat loss, on the basis of rodent work reporting reduced fat mass and increased fat oxidation 12
  • Studied as a local treatment in knee osteoarthritis and cartilage repair (phase 2, with mixed results)
  • Sold and used on the grey market for 'targeted fat burning'; no published human study supports this use
  • Marketed as an ingredient in some cosmetic and supplement formulations in the US; we found no FDA record confirming that status

Dosing

Dose
In user protocols typically 250-500 mcg per day subcutaneously; in clinical studies 1 mg per day was studied orally
Frequency
Once daily, in user protocols often fasted in the morning
Route
Subcutaneous in research use; the published clinical studies used oral administration
Duration
12 weeks in studies; outside a study setting 4-12 weeks are described
  • There is no approved or clinically validated dosing schedule for subcutaneous AOD-9604.
  • The subcutaneous doses mentioned come from online user protocols, not from controlled studies. They are not comparable to the oral doses from the clinical programme.
  • The idea that injecting near a fat depot leads to local fat burning is not substantiated by published research in humans.
  • Because human evidence of efficacy is absent, any dosing schedule is essentially speculative.
  • The schedule in the section below is what circulates among users and vendors, recorded because readers encounter it and not because it is validated. Note a standing unit-confusion trap: AOD-9604 is dosed in micrograms (250-500 mcg) but sold in vials labelled in milligrams (commonly 2 mg or 5 mg), so a decimal error becomes a thousandfold overdose.

These figures describe what the literature and published protocols report. They are not advice and not a dosing instruction.

Protocols

Subcutaneous fat-loss course (user-reported)

user protocol — not validated

Source: Peptide and bodybuilding forums and vendor labelling

This is not a validated schedule. It is a pattern that circulates among users and sellers, reproduced because it is what people actually follow — not because it has been tested. No trial established these doses, this interval or this duration, and nobody is checking what is in the vial. Treat every number below as an assertion, not a finding.

Typical reported daily dose250-500 mcg subcutaneously once daily, most often injected fasted in the morning before cardio
Reported injection sitefrequently into abdominal subcutaneous fat, on the belief that it produces fat loss at the injection site
Reported cycle lengthroughly 4 to 12 weeks, sometimes run continuously, with no consistent off-period

This pattern comes from user reports and vendor labelling; it has no published pharmacokinetic or safety basis. Several things about it are worth flagging plainly. The subcutaneous route was never the one studied: the clinical programme dosed 1 mg orally per day and still missed its phase 2b endpoint, so a 250-500 mcg injection is neither the studied dose nor the studied route. The idea of injecting near a fat depot for local fat burning has no support in any human study. Reports are heavily confounded, since most users run AOD-9604 alongside GH secretagogues, other fragments or a calorie deficit; 'no effect' reports are common and unsurprising given the negative human trial. The compound is very often confused with, or sold interchangeably as, hGH fragment 176-191, from which it differs by an added tyrosine and which cannot be told apart without analysis.

Schedules are reproduced as their source states them. Units, IU and milligrams explains why the figures are not interchangeable between products.

Reconstitution

Vial sizes
2 mg, 5 mg
Solvent
bacteriostatic water (0.9% benzyl alcohol) or sterile water
Storage
Reconstituted 2-8 °C, usually stable for a few weeks. Lyophilised powder cool and dry, protected from light; in the freezer for longer storage.

Worked example

5 mg vial + 2 ml bacteriostatic water = 2.5 mg/ml. A dose of 300 mcg then corresponds to 0.12 ml, or 12 units on a U100 insulin syringe.

Do not shake; let the diluent run down the wall of the vial. The vial sizes and shelf lives given here are common practice for unregistered peptides, not a manufacturer-validated specification. With unregistered product, identity, strength and sterility are not controlled.

Work it out for AOD-9604

Safety

Side effects

  • In the published clinical studies side effects were comparable to placebo
  • Injection site reactions with subcutaneous use: redness, itching, pain
  • Headache and nausea have been reported occasionally
  • No demonstrated effect on glucose tolerance or insulin sensitivity, unlike full-length growth hormone; the fragment did not raise IGF-1 in the rodent work either 2
  • Long-term safety with subcutaneous use has not been studied
  • With unregistered product: risk of contaminants, endotoxins and infection from non-sterile preparation

Do not use if

  • Pregnancy and breastfeeding — no safety data
  • Hypersensitivity to the peptide or to benzyl alcohol in bacteriostatic water
  • Active malignancy — although AOD-9604 does not bind the growth hormone receptor and does not raise IGF-1, this has never been systematically studied
  • Use by competitive athletes: AOD-9604 is named by name on the WADA Prohibited List under S2.2.3, growth hormone analogues and fragments, and is prohibited at all times in and out of competition. Substances in class S2 are non-Specified Substances, which matters at sanctioning: it is a stricter classification than S0, where some sources have wrongly placed this compound 4
  • Use on the assumption that efficacy has been demonstrated — in humans that is not the case

Interactions

Not systematically studied. There are no documented drug interactions. Because AOD-9604 does not activate the growth hormone receptor and does not raise IGF-1 levels, the interactions that apply to growth hormone (with corticosteroids, insulin, thyroid hormone) do not automatically apply here — but this is a line of reasoning, not a research finding.

Sources