Molidustat (Varenzin-CA1) at 5 mg/kg PO q24h for 28 days is the established protocol for nonregenerative anemia associated with chronic kidney disease (CKD) in cats, and it carries FDA conditional approval pending full demonstration of effectiveness.FDA DailyMed An…

The erythropoietic response is clinically meaningful but moderate. Mean hematocrit (HCT) in treated cats rose from a baseline of 23.6% to 27.3% by Day 21 and 27.8% by Day 28, while the control group remained between 20.1% and 23.4% throughout.Journal of Vete… Treatment success — defined as an absolute HCT increase of ≥4 percentage points or a relative increase of ≥25% from baseline — was achieved in 50% (7/14) of molidustat-treated cats versus 16.7% (1/6) of controls on Day 28.FDA DailyMed An… In a continuation phase using 2.5 or 5 mg/kg depending on packed cell volume (PCV), success rates were 75% (6/8) at Day 56 and 62.5% (5/8) at Day 84.FDA DailyMed An…

The dosing cycle is not continuous. The multi-cycle safety study administered molidustat for 28 consecutive days, followed by a treatment pause of at least 7 days, then repeated for up to 4 treatment cycles.FDA DailyMed An… Cats enrolled in that study had a mean age of 13 years, body weights of 2.3–5.9 kg, and represented International Renal Interest Society (IRIS) Stage 2 (31%), Stage 3 (47%), and Stage 4 (22%) CKD.FDA DailyMed An…

Vomiting is the most common adverse effect, occurring in 40% of molidustat-treated cats versus 0% of controls. Increases in systolic blood pressure and mild transient increases in serum potassium were also observed.FDA DailyMed An… The most serious adverse event was a suspected arterial thromboembolism in one treated cat, which presented in lateral recumbency with a cold forelimb after 28 days of treatment and was euthanized.FDA DailyMed An…

No dose adjustment is needed for renal impairment. Molidustat is eliminated with a plasma half-life of 4–6 hours after oral administration in cats, and renal excretion is negligible, making dosing adjustments unnecessary in CKD patients.Journal of Vete…

Molidustat's mechanism avoids the supraphysiologic erythropoietin (EPO) levels associated with recombinant EPO therapy. It produces pulsatile EPO increases of 100–250× endogenous concentrations at 6 hours post-dose, but EPO returns toward baseline between doses rather than remaining persistently elevated.Journal of Vete… This profile is distinct from recombinant human EPO (epoetin, darbepoetin), which is associated with iron deficiency, hypertension, arthralgia, fever, seizures, polycythemia, and life-threatening pure red cell aplasia in cats.Journal of Vete…

Anemia affects 30–65% of CKD cats and worsens with disease stage, reaching 53–65% prevalence in late-stage disease, making effective management a meaningful quality-of-life target.Journal of Vete…+1

ParameterValueSource
Dose5 mg/kg PO q24hJournal of Vete…+1
Treatment cycle28 days on, ≥7 days off, up to 4 cyclesFDA DailyMed An…
Mean HCT at Day 21 (treated vs. control)27.3% vs. 20.1%Journal of Vete…
Mean HCT at Day 28 (treated vs. control)27.8% vs. 23.4%Journal of Vete…
Day 28 treatment success rate50% treated vs. 16.7% controlFDA DailyMed An…
Day 56 success rate (continuation phase)75%FDA DailyMed An…
Day 84 success rate (continuation phase)62.5%FDA DailyMed An…
Vomiting incidence40% treated vs. 0% controlFDA DailyMed An…
Plasma half-life4–6 hoursJournal of Vete…
Regulatory statusFDA conditionally approvedFDA DailyMed An…

Would you like guidance on how to monitor HCT during the treatment cycles and when to adjust the dose between 2.5 and 5 mg/kg?

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Varenzin-CA1 (molidustat oral). FDA Drug Label.
Food and Drug Administration.Updated: 2025-07-21.
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Journal of Veterinary Internal Medicine.2024.Charles S, Süssenberger R, Settje T, et al.
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Journal of Veterinary Internal Medicine.2024.Boegel A, Flamme I, Krebber R, et al.
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Journal of Feline Medicine and Surgery.2025.K Lorbach S, M Quimby J, Nijveldt E, et al.
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What is the current evidence for molidustat in treating… | VetChamp