Roxadustat
FG-4592 · ASP1517 · AZD9941 · Evrenzo · Ai Rui Zhuo
Last updated
At a glance
Overview
Roxadustat earned its niche reputation as the first oral that meaningfully replaces an injection of recombinant EPO. As a HIF prolyl-hydroxylase inhibitor, it tricks the body into the same transcriptional response as moderate altitude — endogenous erythropoietin climbs, hepcidin falls, iron mobilizes, and hemoglobin follows over 2–4 weeks. Endurance athletes, hybrid lifters running cardio-suppressive AAS stacks, and masters-class competitors looking for an oral alternative to rhEPO have driven most of the community interest.
The appeal is mechanistic precision. Unlike injected EPO, which produces a spike-and-crash plasma curve, roxadustat lifts endogenous EPO into a physiologic-to-mid-supraphysiologic band while simultaneously unlocking iron stores — which is why even functional-iron-deficient and inflammation-anemic subjects respond. The same HIF pathway also reliably drops total cholesterol and LDL by 20–40 mg/dL, a useful secondary signal during oral-AAS blocks.
"Roxadustat increased hemoglobin in both ESA-naive and ESA-converted patients in a dose-dependent and titratable manner without the need for intravenous iron supplementation." — Provenzano et al., CJASN (2016)
That said, this is a block-and-pulse compound, not a daily one — the thrombotic risk curve is real, the WADA detection window runs weeks in urine and months in hair, and stacking it on top of testosterone-driven erythrocytosis is the single highest-leverage way to get into trouble. The sections below cover documented roxadustat dosage ranges, weight-tiered TIW protocols, the iron and blood-pressure prerequisites that gate response, stack patterns with AAS for conditioning, and the side-effect profile that defines where the ceiling sits.
How Roxadustat works
HIF Stabilization — The Master Switch#
Roxadustat is a reversible 2-oxoglutarate–mimetic that competitively inhibits all three prolyl hydroxylase domain (PHD1/2/3) enzymes. Under normal oxygen tension, these enzymes hydroxylate the α-subunit of hypoxia-inducible factor (HIF-1α, HIF-2α), tagging it for VHL-mediated ubiquitination and rapid proteasomal degradation. Block the hydroxylase, and HIF-α stops being degraded — it accumulates, translocates to the nucleus, dimerizes with HIF-1β, and lights up every hypoxia-response element in the genome.
The practical consequence: a single oral dose triggers the entire "altitude-adaptation" transcriptome without an oxygen tent, an injection, or a flight to Flagstaff. This is the parent mechanism that everything below flows from.
Endogenous EPO Induction#
HIF-2α is the dominant transcription factor for renal and hepatic erythropoietin. PHD inhibition restores the kidney's ability to manufacture EPO, and plasma EPO rises into the physiologic-to-mid-supraphysiologic range — not the spike-and-crash profile of injected recombinant EPO. Reticulocytes climb within days; hemoglobin moves meaningfully over 2–4 weeks.
"Roxadustat increased hemoglobin in both ESA-naive and ESA-converted patients in a dose-dependent and titratable manner without the need for intravenous iron supplementation." — Provenzano R, Besarab A, Sun CH, et al. Clin J Am Soc Nephrol, 2016
For the endurance-focused user this is the headline: more red cells, more oxygen-carrying capacity, higher VO₂ ceiling — delivered orally, with kinetics that look like physiologic adaptation rather than the sharp pharmacologic spike of EPO injections.
Hepcidin Suppression and Iron Mobilization#
This is the mechanism that separates roxadustat from rhEPO and from testosterone-driven erythropoiesis. HIF upregulates DMT1, DCYTB, ferroportin, transferrin, and transferrin receptor while simultaneously suppressing hepcidin, the hepatic gatekeeper of iron release.
"Roxadustat is a first-in-class oral HIF-PHI that can induce endogenous EPO production and regulate iron metabolism by reducing hepcidin and increasing iron mobilization." — Zhu X, Jiang L, Wei X, Long M, Du Y. Front Pharmacol, 2022
Translation: iron actually leaves the stores and reaches the marrow. In anemia-of-inflammation states — common in heavy contest prep, long deficits, high NSAID exposure, or intense training blocks — hepcidin is elevated and oral iron alone won't move the needle. Roxadustat lifts the hepcidin block at the same time it drives the EPO signal, which is why responder rates in functional iron deficiency beat epoetin alfa in head-to-head data.
Lipid Downregulation via HMGCR#
A consistent off-target effect of HIF stabilization is suppression of HMG-CoA reductase and downstream cholesterol synthesis genes. Across phase 3 trials, total cholesterol and LDL drop by a clinically meaningful margin.
"In multiple phase 3 pivotal trials, roxadustat not only improved anemia but also consistently reduced total cholesterol and LDL by 20–40 mg/dL." — Haase VH, Tanaka T, Koury MJ. Hematology Am Soc Hematol Educ Program, 2024
This is a secondary, opportunistic benefit — not a reason to run the compound — but it's a relevant detail when stacked alongside oral AAS that hammer lipids. The mechanism is independent of the erythropoietic action; lipid drop tracks with HIF activity, not with hemoglobin rise.
Angiogenic and Metabolic Shift#
HIF stabilization also upregulates VEGF, GLUT1, and the glycolytic enzyme cassette (PFK, LDH-A, HK2). The angiogenic signal contributes to capillary density adaptations that overlap with what aerobic base training produces — useful for endurance carryover, but also the basis of the theoretical retinopathy and tumor-growth concerns flagged in the safety section. The glycolytic shift means working tissue gets better at extracting and using glucose under load, which is part of why subjects describe the "altitude lung" feeling within a few weeks rather than waiting for hemoglobin to fully catch up.
The net mechanism is a coordinated, oxygen-sensing program — EPO, iron handling, vascular remodeling, and substrate metabolism move together, because that's how the body evolved to handle hypoxia. Roxadustat hijacks the upstream switch and lets the entire downstream program run from a tablet.
Protocol
| Level | Dose | Frequency | Notes |
|---|---|---|---|
| Low | 50–70 mg/kg TIW | 3× weekly | Documented entry-level range |
| Mid | 70–100 mg/kg TIW | 3× weekly | Most commonly studied range |
| High | 100–150 mg/kg TIW | 3× weekly | Label dosing is TIW (Mon/Wed/Fri). Community endurance blocks commonly run 2× weekly at the same per-dose mg. Food-independent. Reticulocytes rise within days; meaningful Hb response takes 2–4 weeks. |
Cycle length & outcomes
Documented cycle
4–8 weeks
Plateau after
8 wks
Cycle Notes#
Roxadustat is a block-and-pulse compound, not a chronic protocol. The erythropoietic signal builds over weeks and the thrombotic risk curve climbs with sustained exposure, so finite 4–8 week blocks are the rule. There is no hormonal axis to suppress, no PCT, and no taper — but iron status, blood pressure, and hematocrit ceiling are non-negotiable gating factors.
Roxadustat Dosage by Goal#
| Goal | Cycle Length | Per-Dose | Frequency |
|---|---|---|---|
| Endurance / VO₂ block (non-anemic baseline) | 4–6 weeks | 50–70 mg | 2× weekly |
| Aggressive endurance / altitude substitute | 4–6 weeks | 70–100 mg | 3× weekly (M/W/F) |
| On-cycle conditioning support during AAS | 3–4 weeks | 50 mg | 2× weekly |
| Anemia-of-inflammation rescue (late prep) | 3–4 weeks | 70–100 mg | 2× weekly + oral iron |
| Maintenance / hold phase after a block | 2–3 weeks | 50–100 mg | 1× weekly |
The community pattern runs lower frequency than the CKD label (TIW) because non-anemic subjects don't need to fight a uremic anti-erythropoietic milieu — the same per-dose mg produces a faster Hb climb. Aggressive blocks mirror the label cadence; conservative blocks halve it.
Loading and Tapering#
There is no loading phase. A flat dose from day one is standard, and tapering is unnecessary — the half-life is ~10–16 hours and the erythropoietic effect washes out over 8–12 weeks naturally as senescent RBCs are cleared and marrow output normalizes. Some users step down to a 1× weekly "hold" dose for 2–3 weeks at the end of an endurance block to prevent a sharp Hb drop into a competition window, but this is preference, not pharmacology.
"Roxadustat increased hemoglobin in both ESA-naive and ESA-converted patients in a dose-dependent and titratable manner without the need for intravenous iron supplementation." — Provenzano et al., Clin J Am Soc Nephrol (2016)
Onset Timing#
- Reticulocyte rise: 3–5 days after first dose.
- Hepcidin suppression and iron mobilization: within the first week.
- Meaningful Hb delta: 2–4 weeks. Expect +1.0–2.5 g/dL over 4–6 weeks in non-anemic subjects on a 70–100 mg twice-weekly block.
- Lipid drop (LDL/total cholesterol): measurable by week 3–4, typically 20–40 mg/dL.
- Washout: EPO signal normalizes within days of last dose; Hb returns to baseline over 8–12 weeks as RBCs age out.
"Roxadustat is a first-in-class oral HIF-PHI that can induce endogenous EPO production and regulate iron metabolism by reducing hepcidin and increasing iron mobilization." — Zhu et al., Front Pharmacol (2022)
Iron Prerequisites#
The single most common failure mode is initiating a block with depleted iron stores and watching the Hb response stall at week 3. Ferritin >100 ng/mL and TSAT >20% are the practical floor before a block starts. Oral iron bisglycinate at 25–50 mg daily, dosed at least 1 hour separated from the roxadustat tablet, runs throughout the cycle. Calcium, magnesium, and aluminum-containing antacids or phosphate binders also chelate and must be spaced by 1–2 hours.
On-Cycle Bloodwork Cadence#
| Timepoint | Panel |
|---|---|
| Baseline (pre-cycle) | CBC, ferritin, TSAT, lipid panel, BMP (K⁺), LFTs, BP |
| Week 2 | CBC, BP |
| Week 4 | CBC, BP, ferritin |
| End of block | Full repeat: CBC, ferritin, TSAT, lipids, LFTs, BP |
The two numbers that decide whether to continue, hold, or pull the block:
- Hematocrit ceiling: 52% is the soft cap, 55% is the hard stop. Pushing past 55% on top of any androgen-driven erythrocytosis is the highest-risk failure mode in this compound's literature.
- Rate of Hb rise: >1 g/dL per 2 weeks is the threshold where thrombotic events cluster in the phase 3 data. Halve the dose or extend dosing intervals if Hb climbs faster than this.
"In multiple phase 3 pivotal trials, roxadustat not only improved anemia but also consistently reduced total cholesterol and LDL by 20–40 mg/dL." — Haase et al., Hematology Am Soc Hematol Educ Program (2024)
Stacking Within a Block#
The compound is non-hormonal and stacks cleanly with anything that isn't already pushing red cell mass. Pairing notes:
- With AAS (especially trenbolone, testosterone esters): conservative dose only (50 mg 2× weekly), and only if baseline HCT is below 50%. Telmisartan or losartan for BP control during the block is the community default.
- With oral iron + B12 + folate: standard endurance block stack. The B-vitamins prevent the substrate side of erythropoiesis from becoming the limiter once iron is unlocked.
- With statins or bempedoic acid: redundant on lipids but otherwise neutral.
- Avoid: gemfibrozil (CYP2C8 inhibition raises AUC sharply), concurrent rhEPO (additive thrombotic risk with no rational benefit), and any stack that already has HCT above 52%.
Cycle Length Ceiling#
Eight weeks is the practical maximum for a continuous block. Beyond that, the thrombotic risk curve climbs without proportionate Hb gain (the response plateaus around weeks 6–8), and ferritin depletion becomes the limiter regardless of oral iron. Subjects running back-to-back blocks should leave at least 8 weeks off between cycles to let Hb normalize and ferritin recover, with a fresh baseline CBC and ferritin before reinitiating.
Anti-Doping Note#
For anyone tested under WADA, USADA, or federation-level programs (including masters track, tested PL, and many cycling federations), roxadustat is a category S2 prohibited substance at all times. Detection windows are long:
"After a single oral 100 mg dose, roxadustat was detectable in urine for at least 19–20 days at sub-ng/mL sensitivity and in hair at pg/mg range, supporting long detection windows for anti-doping purposes." — Alvarez et al., J Pharm Biomed Anal (2024)
A 4–6 week block leaves a urinary trail measured in months and a hair trail measured in quarters. This is a recreational and untested-athlete compound by realistic application.
Risks & mistakes
Common (most users)#
- Headache and mild nausea during titration — typically resolves within the first 1–2 weeks as Hb stabilizes. Dosing with food softens the GI signal; splitting a 100mg dose into two 50mg administrations on the same day is an option when nausea is dose-limiting.
- Hypertension — the most consistent finding across phase 3 data. Mechanism is rapid Hb rise plus EPO-mediated vasoconstriction. Mitigation: baseline BP <140/90 before initiation, an ARB (telmisartan, losartan) or low-dose ACE inhibitor on standby, and weekly BP checks during the first 4 weeks. Back off one tier (e.g. 100mg → 70mg TIW) for any sustained reading >150/95.
- Peripheral edema — usually mild, ankles/hands. Sodium discipline and the same ARB used for BP handles it.
- Mild ALT/AST elevation, occasional bilirubin bumps — documented in the overdose case at 1× ULN range and resolving on discontinuation (Zhang 2024). Check LFTs at baseline and end-of-block.
- Ferritin drop — not a side effect of the drug per se but a near-universal consequence of the erythropoietic pull. Oral iron bisglycinate 25–50mg daily (separated >1h from the roxadustat dose to avoid chelation) keeps ferritin from flooring. Initiate with ferritin >100ng/mL and TSAT >20% or the response is blunted anyway.
- Hyperkalemia — mild, more relevant in subjects with impaired renal function. A baseline BMP catches the at-risk population.
Uncommon (dose-dependent or individual)#
- Hb overshoot (>13 g/dL in non-anemic baselines, hematocrit >55%) — the single most actionable mitigation point. CBC every 2 weeks during a block; if Hb is climbing >1 g/dL per 2 weeks or hematocrit crosses 54%, the dose is halved or the cycle terminated. This is where the thrombotic risk curve bends sharply upward.
- Accelerated/resistant hypertension — distinct from the mild titration bump. Persistent readings >160/100 despite an ARB call for discontinuation, not dose adjustment.
- Insomnia, vivid dreams — anecdotal, dose-related, often resolves with a morning rather than evening dose.
- Hypoglycemia in diabetic subjects — HIF stabilization modestly increases insulin sensitivity and glucose uptake via GLUT1 upregulation. Continuous glucose monitoring or more frequent fingersticks for anyone on insulin or sulfonylureas during the first 2 weeks.
- LDL/total cholesterol drop of 20–40 mg/dL (Haase 2024) — listed here as a "watch" rather than a problem; it's a favorable off-target effect, but statin doses may need temporary reduction to avoid driving LDL too low during a concurrent oral-AAS block.
- Sub-clinical CYP2C8 interactions — gemfibrozil, clopidogrel, and trimethoprim raise roxadustat AUC meaningfully. Switch agents or drop the per-dose mg by ~30% during overlap.
Rare but serious#
- Thromboembolism — DVT, PE, MI, stroke, vascular-access thrombosis. The FDA's 2021 CRDAC vote against approval rested on a numerically higher thrombotic event rate vs. ESAs in non-dialysis CKD (Devarasetty 2022; Haase 2024). Risk scales with the rate and magnitude of Hb rise — overshoots and pre-existing erythrocytosis are where events cluster. Warning signs: unilateral calf swelling/pain, pleuritic chest pain or sudden dyspnea, sudden focal neurologic deficit, crushing chest pain. Any of these → discontinue immediately, present for evaluation.
- Pulmonary hypertension — uncommon, VEGF-mediated pulmonary vascular remodeling proposed as mechanism. Progressive exertional dyspnea out of proportion to training status warrants workup and discontinuation.
- Seizures — reported at low incidence in CKD trials, mechanism unclear; rapid BP rise is one candidate.
- Acceleration of HIF-driven tumor growth (theoretical) — VEGF and the HIF transcriptome are central to RCC, hepatocellular carcinoma, and several other malignancies. No clinical signal in trials to date, but follow-up is short. Any unexplained weight loss, hematuria, or RUQ pain during or after a block is investigated, not rationalized.
- Worsening of proliferative retinopathy — relevant for diabetic subjects with established retinal disease. A baseline retinal exam is the appropriate filter.
Hard contraindications#
- Baseline hematocrit >52% or any history of polycythemia vera. Stacking roxadustat on top of androgen-driven erythrocytosis is the highest-risk failure mode in this audience. Phlebotomy and a normalized baseline come first, or the cycle does not happen.
- Active or recent (within 6 months) thromboembolic event — DVT, PE, MI, CVA.
- Untreated severe hypertension (>160/100). Treat first, then consider initiation.
- Pregnancy or pregnancy potential without contraception. HIF stabilization is developmentally essential; animal teratogenicity is documented. Non-negotiable.
- Active malignancy, particularly RCC, hepatocellular carcinoma, and other HIF-dependent tumors.
- Co-administration with strong CYP2C8 inhibitors (gemfibrozil) without a dose reduction protocol.
- Concurrent recombinant EPO or darbepoetin. Pick one erythropoietic driver, not two.
- WADA-tested competition. Roxadustat is a category S2 prohibited substance at all times, detectable in urine for ≥3 weeks after a single 100mg dose and in hair at pg/mg for months (Alvarez 2024; Checkouri 2024). This includes federation-tested powerlifting meets and masters track.
Gender-specific and PCT considerations#
Roxadustat is non-hormonal and does not engage the HPTA, so no PCT is required and the same weight-tiered dosing applies across the full subject pool. Women generally reach target Hb at lower per-dose mg simply because baseline Hb is lower — starting at the 50mg twice-weekly tier and titrating off CBC, rather than scaling by sex, is the cleaner approach. Pregnancy remains a hard contraindication. The erythropoietic effect washes out over roughly 8–12 weeks after discontinuation as the marrow returns to baseline output and the existing RBC cohort ages out on its normal ~120-day lifespan — no ancillary is needed during the taper, but a follow-up CBC at 8 weeks post-cycle confirms normalization.
FAQ — Roxadustat
Research & citations
6 studies cited on this page.
Conclusion
Roxadustat is a high-leverage oral HIF-PHI for physique and endurance-focused protocols — unlocking endogenous EPO production, iron mobilization, and a consistent boost in aerobic capacity when cycling is designed around iron status and risk management.
Key takeaways:
- Typical protocol: 70–100 mg orally, two to three times weekly for 4–8 weeks (TIW for clinical, 2× weekly often seen in performance blocks)
- Food-independent absorption — but oral iron, calcium, or magnesium is separated by at least 1 hour to avoid chelation blocks
- Iron status (ferritin ≥100 ng/mL, TSAT ≥20%) is a practical prerequisite for meaningful Hb rise; oral bisglycinate stacked where needed
- Aggressive cycling beyond 150 mg TIW or combination with AAS-driven polycythemia pushes thrombotic risk sharply higher
- Stacks cleanly with oral iron, ARBs/ACE inhibitors for BP, and cardio-focused blocks; non-hormonal, with no PCT required
- Detection windows are long — ≥3 weeks in urine, longer in hair — so federation-tested athletes should regard it as a season-ending detection risk
For experienced users optimizing endurance, work capacity, or recovery from anemia, roxadustat offers powerful EPO-axis manipulation with oral convenience, provided baseline hematocrit, iron, and blood pressure are regularly checked and cycle-planning is methodical.