Roxadustat — Safety, Research, Risks & Legal Status

Not medical advice. Roxadustat is discussed here for informational and harm-reduction purposes only. We do not endorse use, and any dosing context is informational, not a protocol.

Also known as	FG-4592, ASP1517, AZD9941, Evrenzo (brand, EU/Japan), Aizeming (China)
Category	Research Chemical
Drug class	Hypoxia-inducible factor prolyl-hydroxylase inhibitor (HIF-PHI)
Developer / partners	FibroGen, with Astellas and AstraZeneca
Route	Oral tablet, three times weekly (approved use)
US status	Not FDA-approved; CRL issued August 2021 for CKD anemia
Approved elsewhere as	Evrenzo (China 2018, Japan, EU 2021, others) for anemia of CKD
Anti-doping status	WADA Prohibited List class S2, banned at all times
US legal status	In the United States, roxadustat is NOT FDA-approved for any indication. The FDA issued a Complete Response Letter in August 2021 declining approval for anemia of chronic kidney disease and requiring an additional safety trial; AstraZeneca subsequently returned US rights and the CKD program was not resubmitted. In the US it is an investigational drug, not a lawful dietary supplement or OTC product, and consumer-facing material sold online is unapproved and typically labeled "for research use only, not for human consumption." Roxadustat IS an approved prescription medicine elsewhere, including China (first approval December 2018), Japan, the EU/EEA, South Korea and Chile, dispensed under the brand Evrenzo (or local names) for anemia of CKD. It is a prescription drug in those markets, never a supplement. For athletes, roxadustat is prohibited at all times by the World Anti-Doping Agency under class S2 (hypoxia-inducible factor activating agents / erythropoiesis-stimulating agents), and multiple athletes have been sanctioned for its use.

What is Roxadustat?

Roxadustat is an orally administered, first-in-class small-molecule hypoxia-inducible factor prolyl-hydroxylase inhibitor (HIF-PHI) developed by FibroGen with partners Astellas and AstraZeneca. It was designed as a pill-form alternative to injectable erythropoiesis-stimulating agents (ESAs such as epoetin) for treating anemia of chronic kidney disease. By blocking the enzymes that tag HIF-alpha for degradation when oxygen is adequate, roxadustat makes the body behave as though it were mildly oxygen-deprived, switching on endogenous erythropoietin production, improving iron absorption and mobilization, and down-regulating hepcidin. It is a genuine, regulator-approved medicine in several countries but was rejected by the FDA on safety grounds, and it is a WADA-banned substance with documented misuse as a blood-boosting doping agent in endurance sport. On this site it is covered as a reference entry only; we do not sell it and nothing here is medical advice.

How it works

Under normal oxygen levels, prolyl-hydroxylase domain enzymes (PHD1-3) hydroxylate proline residues on the alpha subunits of hypoxia-inducible factor (HIF-1-alpha and HIF-2-alpha), which flags them for von Hippel-Lindau-mediated ubiquitination and rapid degradation. Roxadustat is a reversible, orally bioavailable competitive inhibitor of these prolyl-hydroxylases; it is proposed to act by mimicking 2-oxoglutarate, a co-substrate of the enzymes. Inhibiting PHDs stabilizes HIF-alpha, which dimerizes with HIF-beta and drives transcription of hypoxia-response genes - most importantly erythropoietin, as well as genes governing iron uptake and transport, while down-regulating hepcidin. The net effect mimics the body's natural adaptation to reduced oxygen and increases red-cell production. Because HIF regulates a large gene network (including VEGF and other angiogenic and metabolic genes), the proposed mechanism also underlies the theoretical off-target concerns; some in-vitro work further suggests roxadustat has HIF-independent effects on redox metabolism and mitochondrial function that are still being characterized.

Background & history

FibroGen developed the compound during the 2000s as an oral HIF-PHI to compete with injectable ESAs for renal anemia. It licensed Japanese rights to Astellas (2004) and broader European/Middle East/CIS rights to Astellas (2006), then partnered with AstraZeneca in 2013 for the US, China and other territories, with a China profit-share. Roxadustat became the first HIF-PHI to reach Phase 3 and the first small-molecule HIF-PHI approved for renal anemia, gaining its first approval in China in December 2018, followed by Japan and, in August 2021, the EU (as Evrenzo). The US trajectory diverged sharply: an FDA advisory committee voted against approval in July 2021, the FDA issued a Complete Response Letter in August 2021 asking for a new safety trial, FibroGen disclosed that earlier safety analyses had been favorably adjusted post hoc, and AstraZeneca ultimately relinquished US rights. WADA added HIF stabilizers including roxadustat to its Prohibited List in 2019, after anti-doping authorities had already been testing for the class for years.

What the research says

The human evidence base for the approved indication (anemia of CKD) is substantial and comes from large randomized Phase 3 programs in both dialysis-dependent and non-dialysis-dependent patients. Pooled and individual trials show roxadustat is superior to placebo and broadly non-inferior to ESAs (epoetin alfa, darbepoetin) for correcting and maintaining hemoglobin, which is why it was approved in China, Japan and the EU. The controversy is on safety, not efficacy: the FDA's advisory committee voted heavily against approval (13-1 and 12-2) citing thromboembolic risk, and it later emerged that FibroGen had presented post-hoc-adjusted safety analyses that looked more favorable than the pre-specified analysis. Beyond CKD anemia, human data are far thinner and largely investigational: roxadustat has been studied or is in trials for anemia in lower-risk myelodysplastic syndromes (an FDA-cleared Phase 3 with orphan designation) and chemotherapy-induced anemia, and preclinical work explores fibrosis, ischemia and even anti-tumor ferroptosis effects. Its use as an endurance-performance aid is not supported by controlled efficacy trials in athletes; the rationale is extrapolated from its proven ability to raise hemoglobin, and it is banned rather than studied for that purpose.

Reported effects

Raises hemoglobin and hematocrit by stimulating endogenous erythropoietin production (the intended, well-documented effect)
Increases iron absorption and mobilization and lowers hepcidin, unlike injectable ESAs
In athletes, the theorized benefit is higher oxygen-carrying capacity, improved aerobic/endurance capacity and recovery (extrapolated, not validated in athlete trials)
Corrects anemia of chronic kidney disease with oral rather than injectable dosing
Mimics the physiologic response to hypoxia across many HIF-regulated genes, so effects are broad and not limited to red-cell production
Hypertension and elevated blood pressure are common on-target consequences of raising red-cell mass

Dosing & administration (informational)

Informational only, not a protocol and not a recommendation. In the regulated CKD setting, Evrenzo is prescribed as oral tablets taken three times per week on non-consecutive days, with the dose individually titrated by a physician to reach and maintain hemoglobin roughly in the 10-12 g/dL range; starting doses in the label are weight- and prior-ESA-dependent, and dose is adjusted based on hemoglobin response and safety labs. These figures describe how the approved drug is used under medical supervision with regular monitoring of hemoglobin, potassium and blood pressure. They are not guidance for self-administration, and there is no established, safe self-dosing regimen for non-medical or performance use.

This is general research/context information, not medical advice or a recommended protocol.

Safety & side effects

Increased risk of thromboembolic events - including vascular access thrombosis, deep vein thrombosis and pulmonary embolism - was the central FDA safety concern and drove the CKD rejection
Signals for increased major adverse cardiovascular events (MACE) and, in some meta-analyses, higher all-cause mortality versus comparators
Hyperkalemia (elevated potassium) is a recognized adverse effect requiring monitoring, particularly in non-dialysis patients
Hypertension is common and can be clinically significant as hemoglobin rises
Broad HIF activation raises theoretical concerns about promoting angiogenesis, tumor growth, cyst growth and pulmonary/vascular effects; the clinical data are mixed and this remains an area of active study
Common GI and infectious adverse events reported in trials include diarrhea, nausea, urinary tract infection, nasopharyngitis, peripheral edema and headache
Non-pharmaceutical-grade material sold as a 'research chemical' carries additional risks of misidentification, wrong dose, and contamination that clinical-trial data do not address

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Who should avoid it

People with a history of thrombosis, stroke, heart attack, or other thromboembolic or major cardiovascular events
Athletes subject to anti-doping testing (WADA S2, prohibited at all times, in and out of competition)
Anyone who cannot regularly monitor hemoglobin, potassium and blood pressure under medical supervision
People who already have a high or normal hemoglobin/hematocrit, where further red-cell increase raises clot risk
Pregnant or breastfeeding individuals, given HIF's role in development and the absence of adequate human safety data
Anyone with an active or recent malignancy, given unresolved theoretical concerns about HIF-driven tumor and angiogenesis effects

How it is commonly combined

This site does not endorse stacking roxadustat with anything. In the non-medical context where it is misused, combining it with any other erythropoiesis-stimulating agent, iron loading, altitude/hypoxic training, or other cardiovascular stressors is specifically dangerous because it multiplies the same thromboembolic and blood-pressure risks that led the FDA to reject the drug. There is no evidence-based, safe stack.

Legal & regulatory. In the United States, roxadustat is NOT FDA-approved for any indication. The FDA issued a Complete Response Letter in August 2021 declining approval for anemia of chronic kidney disease and requiring an additional safety trial; AstraZeneca subsequently returned US rights and the CKD program was not resubmitted. In the US it is an investigational drug, not a lawful dietary supplement or OTC product, and consumer-facing material sold online is unapproved and typically labeled "for research use only, not for human consumption." Roxadustat IS an approved prescription medicine elsewhere, including China (first approval December 2018), Japan, the EU/EEA, South Korea and Chile, dispensed under the brand Evrenzo (or local names) for anemia of CKD. It is a prescription drug in those markets, never a supplement. For athletes, roxadustat is prohibited at all times by the World Anti-Doping Agency under class S2 (hypoxia-inducible factor activating agents / erythropoiesis-stimulating agents), and multiple athletes have been sanctioned for its use.

Quality & harm reduction

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Frequently asked questions

Is roxadustat FDA-approved?

No. The FDA declined to approve it for anemia of chronic kidney disease in an August 2021 Complete Response Letter, requiring an additional safety trial, and the US program was not pursued further. It is approved in China, Japan, the EU and several other countries, but not the United States.

Why did the FDA reject roxadustat when other regulators approved it?

The FDA's concern was safety, not efficacy. Its advisory committee voted heavily against approval over increased thromboembolic and cardiovascular risk, and FibroGen disclosed that some safety analyses had been favorably adjusted post hoc. The EU and others weighed the same data differently and approved it as Evrenzo.

Why is roxadustat banned in sports?

Because it reliably raises hemoglobin and therefore oxygen-carrying capacity, it functions as an oral blood-booster comparable to EPO. WADA lists it under class S2 (HIF activating agents / ESAs), prohibited at all times, and athletes have been sanctioned for it. It is detectable in anti-doping testing.

Does it actually improve endurance performance?

There are no controlled efficacy trials in athletes. The presumed benefit is inferred from its documented ability to raise hemoglobin in patients. Because it is banned and carries real clot and cardiovascular risk, it is studied as a doping agent to detect, not as a performance aid to validate.

What are the main safety concerns?

The dominant concern is thromboembolic events - clots, including vascular access thrombosis, DVT and pulmonary embolism - along with signals for increased major adverse cardiovascular events and, in some analyses, mortality. Hyperkalemia and hypertension are also recognized, plus unresolved theoretical concerns about broad HIF activation affecting angiogenesis and tumor growth.

What is a safe dose to take on my own?

We do not provide dosing guidance. In its approved use, roxadustat is prescribed and titrated by a physician against hemoglobin, potassium and blood pressure labs. There is no established safe self-administered dose, and using unregulated research-chemical material compounds the risk. Talk to a qualified clinician.

References & further reading

PubMed: roxadustat FG-4592 HIF prolyl hydroxylase inhibitor mechanism
PubMed: roxadustat cardiovascular safety thromboembolic meta-analysis chronic kidney disease
PubMed: roxadustat anemia non-dialysis CKD randomized phase 3
ClinicalTrials.gov: roxadustat myelodysplastic syndromes anemia
PubMed: hypoxia-inducible factor stabilizer roxadustat doping control detection