ATX-304
Also known as: O304, O-304
ATX-304 (also called O304 or O-304) is an oral small-molecule AMPK activator (investigational). ATX-304, first described as O304, raises AMP-activated protein kinase (AMPK) activity without lowering cellular energy levels. Instead of binding the enzyme as an allosteric activator, it protects the activated, phosphorylated form (threonine 172) from being switched off by phosphatases, and it needs the upstream kinase LKB1 to work.
For research use only.
Key Facts
- CAS
- 1261289-04-6
- Molecular Weight (MW)
- 380.2 g/mol
- Half-life
- Long; plasma levels did not reach steady state until about day 14 of daily dosing. No numeric human half-life has been published.
- FDA status
- Not Approved
- Evidence level
- Limited Human Evidence
- Human dose established
- Yes
- Administration Route
- Oral
- Frequency
- Once daily
- Last updated
- Oct 5, 2026
- Reviewed
- Oct 5, 2026
- Targets
- AMPK (pan-isoform)Mitochondrial respiration (uncoupling)
Vendor price snapshot
Each vendor's price is the median price per mg of its own listings; with fewer than 3 vendors there is no typical range. From public vendor listings collected in Feb 2026, so confirm the live price on the vendor site. Peptide Library does not sell peptides.
- Vendors listing this peptide
- 1
- Listed offers
- 1
- Price per mg
- $2.00/mg
Research summary
Investigational oral small-molecule AMPK activator, formerly O304, tested in two small human trials in type 2 diabetes and in obesity with prediabetes. Not FDA-approved. Prohibited in sport as an AMPK activator under WADA S4.4.1.
Peptide Library's ATX-304 profile summarises 5 cited studies listed in the Science section, the compound's regulatory status, and research-protocol parameters reported for it. It is a research reference, not medical advice.
ATX-304 dosage chart
ATX-304 (formerly O304) has been given to people in two small placebo-controlled trials: 1,000 mg once daily by mouth for 28 days in a 65-patient phase 2a trial in type 2 diabetes, and 400 mg once daily for 8 weeks in a 23-person phase 1b trial in obesity with prediabetes. These were short exploratory studies of an investigational drug, not an established therapeutic regimen, and no product containing it is approved anywhere. It is also not a peptide: it is a small-molecule AMPK activator.
| Human dosing established | Yes |
|---|---|
| Studied dose range | 400–1,000 mg orally once daily (two trials, different formulations) |
| Route | Oral |
| Frequency | Once daily |
| Duration studied | 28 days to 8 weeks in the trials, with an optional open-label extension to 16 weeks in the phase 1b |
| Titration | None reported. Each trial used a single fixed dose. |
| Half-life | Long; plasma levels did not reach steady state until about day 14 of daily dosing. No numeric human half-life has been published. |
| Evidence level | Limited Human Evidence |
| Last reviewed | 2026-10-05 |
Research-reported dosing
Doses as studied, one row per regimen. Different trials used different regimens; they are listed separately rather than averaged.
| Study / context | Population | Dose | Route | Frequency | Duration | Outcome studied | Source |
|---|---|---|---|---|---|---|---|
| Steneberg et al., 2018 — TELLUS phase 2aClinical trial · Randomised, double-blind, placebo-controlled phase 2a | Adults with type 2 diabetes on metformin (n=65, ATX-304 and placebo arms) | 1,000 mg | Oral suspension | Once daily | 28 days | Fasting plasma glucose, HOMA-IR, blood pressure and calf-muscle microvascular perfusion; safety | Steneberg P et al. PAN-AMPK activator O304 improves glucose homeostasis and microvascular perfusion in mice and type 2 diabetes patients. JCI Insight. 2018. |
| Thieroff-Ekerdt et al., 2026 — phase 1b (conference abstract)Clinical trial · Randomised, double-blind, placebo-controlled phase 1b; ADA 2026 abstract | Adults with obesity and prediabetes (n=23, randomised 2:1 to ATX-304 or placebo) | 400 mg | Oral tablets (sodium salt) | Once daily | 8 weeks, with an optional open-label extension to 16 weeks | Safety, pharmacokinetics, adiponectin, liver and visceral fat by MRI, resting metabolic rate | Thieroff-Ekerdt RI et al. 1782-P: Phase 1b Study of AMPK/Mitochondrial Activator ATX-304 in Prediabetic Obese Participants. Diabetes. 2026;75(Supplement_1). |
Preclinical and analog research
Not human dosing evidence. Listed for completeness and never extrapolated to a human dose.
| Study / context | Population | Dose | Route | Frequency | Duration | Outcome studied | Source |
|---|---|---|---|---|---|---|---|
| Preclinical — aged micePreclinical · Rodent study | Aged mice | 0.25 or 0.5 mg per gram of diet; not convertible to a human dose | Oral (in feed) | — | 12 months | Metabolic and cardiac function, exercise capacity | Ericsson M et al. AMPK activator O304 improves metabolic and cardiac function, and exercise capacity in aged mice. Commun Biol. 2021. |
| Preclinical — diet-induced fatty liver disease (MASLD)Preclinical · Rodent study | Mice on a choline-deficient high-fat diet | 1 mg per gram of diet; not convertible to a human dose | Oral (in feed) | — | — | Fat mass, blood cholesterol, liver steatosis and fibrosis | Holm E et al. AMPK activator ATX-304 reduces oxidative stress and improves MASLD via metabolic switching. JCI Insight. 2025. |
Where sources disagree
- The two trials used different formulations (an oral suspension in 2018, sodium-salt tablets in the phase 1b), so 1,000 mg and 400 mg are not directly comparable exposures. Neither trial compared doses, so neither identifies an optimal one.
- The phase 1b results are so far published only as a conference abstract and company announcements, not a full peer-reviewed paper. The abstract reports resting metabolic rate rising up to 33% from baseline; the company's announcement reports an 8% increase. Minimal weight loss was reported at 400 mg daily.
- The 2018 paper lists two ClinicalTrials.gov numbers for the TELLUS trial (NCT00508287 and NCT01167881), but both belong to unrelated trials by other sponsors. The phase 1b is registered in the EU Clinical Trials Information System as 2023-505967-36-00.
- ATX-304 is not named on the WADA Prohibited List, but section S4.4.1 prohibits AMPK activators as a class at all times (its examples are AICAR, BAM15 and MOTS-c).
- Products sold online as ATX-304 or O-304 are research chemicals, not the trial material. Their identity, purity and salt form are unverified, and trial doses describe the trial formulations only.
Handling & administration
- Reconstitution Guide
- Not applicable: taken by mouth (oral suspension and tablets in the trials)
Sequence & molecular data
| Molecular formula | C16H11Cl2N3O2S |
|---|---|
| Molecular weight | 380.2 g/mol |
| CAS number | 1261289-04-6 |
| Half-life | Long; plasma levels did not reach steady state until about day 14 of daily dosing. No numeric human half-life has been published. |
| Appearance | Crystalline solid |
| Formulation | Oral tablet (trials) |
| PubChem CID | 50923806 |
| FDA UNII | SPS2TLH4CM |
Identifiers link to the public PubChem, FDA Substance Registration (UNII), ChEMBL and DrugBank records for the same entity.
Science
Mechanism of Action
ATX-304, first described as O304, raises AMP-activated protein kinase (AMPK) activity without lowering cellular energy levels. Instead of binding the enzyme as an allosteric activator, it protects the activated, phosphorylated form (threonine 172) from being switched off by phosphatases, and it needs the upstream kinase LKB1 to work. It also acts as a mitochondrial uncoupler, increasing cellular respiration. In mice it increased glucose uptake in skeletal muscle and heart and raised energy expenditure, and in rodents it does not cross the blood–brain barrier.
Origin
Synthetic thiadiazole small molecule from Betagenon AB and Umeå University, Sweden; now developed by Amplifier Therapeutics, a Cambrian Bio company.
Targets
Studies
- PAN-AMPK activator O304 improves glucose homeostasis and microvascular perfusion in mice and type 2 diabetes patients
- AMPK activator O304 improves metabolic and cardiac function, and exercise capacity in aged mice
- O304 ameliorates hyperglycemia in mice by dually promoting muscle glucose effectiveness and preserving β-cell function
- AMPK activator ATX-304 reduces oxidative stress and improves MASLD via metabolic switching
- O304 is a mitochondrial uncoupler which extends C. elegans lifespan and induces vasorelaxation of rat mesenteric arteries
Regulatory & research status
ATX-304 is not an FDA-approved product. It is sold for laboratory research and has no approved medical use.
| FDA status | Not Approved |
|---|---|
| Research status | Investigational; clinical development reported |
| Availability | Research-Only |
| WADA (sport) | Banned in Sport |
| Library classification | Clinical Trial |
Benefits
ATX-304 side effects
ATX-304 has only limited human data, so the list below is incomplete and its side-effect profile is not well established.
Side Effects
- Mostly mild adverse events, at a rate similar to placebo (phase 1b)
Storage & stability
Lyophilized (freeze-dried) peptide powder is far more stable than the reconstituted solution. Keep sealed vials cold, dry and away from light; long-term storage is typically frozen, with short-term refrigeration for vials in use.
Once reconstituted in bacteriostatic water, keep the solution refrigerated, avoid repeated freeze–thaw cycles and agitation, and label the vial with the reconstitution date and concentration. Discard any solution that turns cloudy or shows particulates.
Degradation rates differ by sequence: peptides containing methionine, cysteine, asparagine or glutamine are more prone to oxidation and deamidation, so shelf life after reconstitution is compound-specific rather than universal.
Read the full guide: how to store peptides before and after reconstitution →
Source: Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. Stability of protein pharmaceuticals: an update. Pharm Res. 2010;27(4):544–575. (PMID 20143256). General guidance for research handling; not product-specific instructions.
ATX-304: frequently asked questions
What is ATX-304?
Investigational oral small-molecule AMPK activator, formerly O304, tested in two small human trials in type 2 diabetes and in obesity with prediabetes. Not FDA-approved. Prohibited in sport as an AMPK activator under WADA S4.4.1.
How does ATX-304 work?
ATX-304 raises AMPK activity by protecting the enzyme’s activated, phosphorylated form from being switched off, rather than by lowering cellular energy levels, and it also acts as a mitochondrial uncoupler. In mice this increased glucose uptake in muscle and heart and raised energy expenditure.
Is ATX-304 a peptide?
No. ATX-304 is a small synthetic molecule (C16H11Cl2N3O2S, about 380 g/mol) that is taken by mouth. It is listed here because it is sold and discussed alongside peptides such as MOTS-c.
What doses of ATX-304 have been studied in humans?
Two placebo-controlled trials have reported doses: 1,000 mg once daily as an oral suspension for 28 days in 65 adults with type 2 diabetes (JCI Insight, 2018), and 400 mg once daily as tablets for 8 weeks in 23 adults with obesity and prediabetes (ADA 2026 abstract). These were short exploratory studies, not an established regimen.
What are the side effects of ATX-304?
Human safety data are limited to two short trials. The 28-day trial described ATX-304 as well tolerated with no ECG abnormalities, and the 8-week phase 1b reported mostly mild adverse events at a rate similar to placebo, with none related to body temperature, flushing or heart rate. Long-term safety is unknown. This is reference information, not medical advice.
Is ATX-304 FDA approved?
No. ATX-304 is an investigational drug that has been tested in small European trials and is not approved for any use anywhere. Products sold online under the name are research chemicals.
Is ATX-304 banned in sport?
Yes. ATX-304 is not named on the WADA Prohibited List, but section S4.4.1 prohibits AMPK activators as a class at all times, alongside named examples such as AICAR and MOTS-c. Athletes should check the current list directly, since it is revised every year.
What compounds are similar to ATX-304?
Compounds most often compared with ATX-304 include AICAR, MOTS-c, SLU-PP-332, BAM15 and 5-Amino-1MQ. They are grouped by shared mechanism or research area rather than by equivalence, and their regulatory status and evidence base differ.
References
- PAN-AMPK activator O304 improves glucose homeostasis and microvascular perfusion in mice and type 2 diabetes patients — JCI Insight, 2018External reference
- Phase 1b Study of AMPK/Mitochondrial Activator ATX-304 in Prediabetic Obese Participants — Diabetes (ADA abstract 1782-P), 2026External reference
- EU CT 2023-505967-36-00 — Phase 1B study of ATX-304 Na salt tablets (EU Clinical Trials Information System)External reference
- AMPK activator O304 improves metabolic and cardiac function, and exercise capacity in aged mice — Commun Biol, 2021External reference
- AMPK activator ATX-304 reduces oxidative stress and improves MASLD via metabolic switching — JCI Insight, 2025External reference
- O304 is a mitochondrial uncoupler which extends C. elegans lifespan and induces vasorelaxation of rat mesenteric arteries — Chem Biol Interact, 2025External reference
- WADA Prohibited List 2026External reference
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Compiled by Peptide Library Editorial · Reviewed Oct 5, 2026 · Updated Oct 5, 2026 · Version 1
This ATX-304 profile is compiled from published literature (5 cited studies linked above), public regulatory records and chemical registries. It describes what research reports; it is not medical advice, and nothing here is a dosing recommendation for humans. Peptide Library does not sell peptides. Editorial policy · How profiles are compiled · Report an error
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