Molidustat (Varenzin-CA1) for Cats in 2025 🐱

If your cat has chronic kidney disease and is struggling with anemia, the new veterinary drug Molidustat—sold as Varenzin™-CA1—may offer a life-improving solution. I’m Dr Duncan Houston BVSc, and this 2025 guide explains how Molidustat works, when it should be used, and what precautions cat owners should know 🧬💉

🧬 What Is Molidustat?

Molidustat is a newly conditionally approved drug used to treat non-responsive anemia in cats caused by chronic kidney disease (CKD). It stimulates the body’s production of red blood cells (RBCs) when the kidneys can no longer make enough erythropoietin (EPO).

📦 Product Overview

• 💊 Brand: Varenzin™-CA1
• 💧 Strength: 25 mg/mL oral liquid
• ⚠️ FDA Conditional Approval: For cats only, and only for anemia caused by CKD

📋 How It Works

When oxygen levels drop, the body normally creates hypoxia-inducible factor (HIF), which leads to more EPO production. However, cats with CKD lose this ability. Molidustat works by preventing the destruction of HIF, allowing the kidneys (and other organs like the liver) to continue producing EPO—thus increasing red blood cells and improving oxygen delivery to tissues.

⚙️ How This Medication Is Used

• 🗓️ Given once daily for 28 days
• ⏸️ Followed by a one-week treatment break
• 🔁 Repeat cycles as needed based on red blood cell counts
• 🩸 Monitor packed cell volume (PCV) or hematocrit (HCT) weekly starting at Day 14

🧪 Cats often show a PCV/HCT increase of 2–4% as early as 7 days into treatment.

⚠️ Side Effects

• 🤮 Vomiting in ~50% of cats (usually mild)
• 🩸 Polycythemia (excess RBCs) → increased risk of clots, hypertension, or seizures
• ⚠️ Avoid use in cats with clotting disorders or seizure history

Regular blood testing is essential to detect excessive RBC production and avoid dangerous complications like thickened blood or clot formation 🧬

🚫 When Molidustat Should Not Be Used

• 🚫 Cats under 1 year old
• 🚫 Cats with normal red blood cell counts
• 🚫 Cats with seizure history or abnormal clotting

🔄 Interactions & Staggering Other Medications

Molidustat's absorption can be reduced if given alongside certain drugs:

• 🚫 Phosphate binders
• 🚫 Antacids or sucralfate
• 🚫 Iron supplements

⏳ Stagger these drugs apart from Molidustat to avoid interference. Do not combine with other EPO-stimulating agents without veterinary direction.

📲 Administering Molidustat at Home

• 🍽️ May be given with or without food
• 🧴 Shake well before use
• 🧼 Wash hands after dosing
• 🚫 Do not re-dose if your cat vomits the dose within 15 minutes
• 🔬 Use the syringe provided—do not wash or disassemble it

⚠️ Warning:

If the medication contacts the outside of the syringe, printing can wear off—always insert the syringe securely into the bottle.

🧠 What Molidustat Does *Not* Do

• ❌ Does not treat kidney disease itself
• ❌ Does not work for anemia due to blood loss, infection, or iron deficiency

👉 Iron supplementation is not necessary unless your vet confirms iron deficiency. Otherwise, Molidustat optimizes the iron already available in the body.

📈 Monitoring Schedule

• ✅ Blood tests weekly starting day 14
• ✅ Monitor PCV or HCT trends
• ✅ Adjust dosing cycles based on red blood cell response

Your veterinarian may recommend intermittent or lifelong cyclic use depending on your cat’s disease progression.

📲 Ask a Vet for Personalized Advice

If your cat has kidney disease and anemia, Molidustat may be life-changing. For questions about dosage, side effects, or alternatives, use the Ask A Vet app for expert support 🐱💬

✅ Summary

• ✔️ Molidustat boosts EPO and red blood cells in cats with kidney-related anemia
• ✔️ Use in 28-day cycles with one-week breaks
• ✔️ Monitor red cell levels weekly during treatment
• ⚠️ Avoid in cats with seizures, clotting disorders, or normal RBC levels
• ✔️ Conditionally FDA approved for cats only

Molidustat does not cure kidney disease, but it offers targeted relief from one of CKD’s most exhausting symptoms: chronic anemia. With careful use and monitoring, your cat may gain back energy and vitality 💛

Need support with anemia or CKD management? Download the Ask A Vet app for 1-on-1 help from licensed veterinarians 🩺🐱

— Dr Duncan Houston BVSc