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Voriconazole

Prescription
Second-Generation Triazole Antifungal
Last reviewed 21 Apr 2026 · PetCare.AI Editorial Team
Species
Dog, Cat
Brands
2 available
Interactions
3 documented
Formulations
3

Mechanism of action

Inhibits fungal cytochrome P450-dependent 14α-sterol demethylase, blocking ergosterol synthesis. Extended spectrum over fluconazole including Aspergillus, Fusarium, and many Candida species.

At a glance

Class
Second-Generation Triazole Antifungal
Schedule
Prescription
Storage
Tablets at room temperature; oral suspension refrigerated, use within 14 days; reconstituted IV solution refrigerated

Dosing

🐕

Dog

Used for aspergillosis, fusariosis, and refractory systemic mycoses
Dose
4 mg/kg
Route
PO, IV
Frequency
q12h
🐈

Cat

CAUTION: Cats have significantly reduced voriconazole clearance
Dose
12.5 mg/kg
Route
PO
Frequency
q12h

Formulations

💊

Other — 3

Strength
—
Strength
—
Strength
—

Storage

Tablets at room temperature; oral suspension refrigerated, use within 14 days; reconstituted IV solution refrigerated

Safety

Monitoring parameters

Hepatic enzymesSerum voriconazole levels (TDM recommended)Neurological signs in cats

Interactions

Contraindicated — 2

Phenobarbital
contraindicated
Phenobarbital potently induces CYP2C19 and CYP3A4, reducing voriconazole levels by 50-80%, rendering antifungal therapy ineffective. Voriconazole also inhibits phenobarbital metabolism.
Management: Avoid combination. If both needed, use alternative antifungal (caspofungin, amphotericin B) or alternative anticonvulsant (levetiracetam — no CYP induction).
Cisapride
contraindicated
CYP3A4 inhibition causes cisapride accumulation and fatal cardiac arrhythmias.
Management: NEVER combine. Use metoclopramide as alternative prokinetic.

Major — 1

Cyclosporine (Systemic)
major
Voriconazole potently inhibits CYP3A4, increasing cyclosporine levels 2-3 fold.
Management: Reduce cyclosporine dose by 50%. Monitor trough levels closely.

Brands

Other markets

Vfend
Vorico

FAQs

Frequently asked questions

›What is Voriconazole?
Voriconazole is a second-generation triazole antifungal used in pets. Inhibits fungal cytochrome P450-dependent 14α-sterol demethylase, blocking ergosterol synthesis. Extended spectrum over fluconazole including Aspergillus, Fusarium, and many Candida species.
›What is Voriconazole used for in pets?
Voriconazole is used in veterinary medicine for: Used for aspergillosis, fusariosis, and refractory systemic mycoses; CAUTION: Cats have significantly reduced voriconazole clearance.
›What is the Voriconazole dose for dogs?
For dogs, Voriconazole is typically dosed as follows — Used for aspergillosis, fusariosis, and refractory systemic mycoses: 4 mg/kg PO/IV q12h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What is the Voriconazole dose for cats?
For cats, Voriconazole is typically dosed as follows — CAUTION: Cats have significantly reduced voriconazole clearance: 12.5 mg/kg PO q12h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›Does Voriconazole need a prescription?
Yes. Voriconazole is a prescription medication and should only be administered under veterinary supervision.

References

References

Textbooks & handbooks

  • Plumb, D.C. Plumb's Veterinary Drug Handbook. 10th ed., Wiley-Blackwell, 2023.
  • Vail, D.M., Thamm, D.H., & Liptak, J.M. (eds.). Withrow & MacEwen's Small Animal Clinical Oncology. 6th ed., Saunders/Elsevier, 2020.
  • Riviere, J.E., & Papich, M.G. (eds.). Veterinary Pharmacology and Therapeutics. 10th ed., Wiley-Blackwell, 2018.
  • National Research Council. Nutrient Requirements of Dogs and Cats. National Academies Press, Washington DC, 2006.
  • The Merck Veterinary Manual. Merck & Co., Online edition. https://www.merckvetmanual.com/

Clinical guidelines & consensus

  • Fletcher, D.J., Boller, M., Brainard, B.M., et al. "RECOVER Evidence and Knowledge Gap Analysis on Veterinary CPR." Journal of Veterinary Emergency and Critical Care, 2012;22(S1):S102–S131.
  • American Animal Hospital Association. 2018 AAHA Diabetes Management Guidelines for Dogs and Cats. AAHA Press.

Journals & peer-reviewed studies

  • Hogan, D.F., Fox, P.R., Jacob, K., et al. "Secondary prevention of cardiogenic arterial thromboembolism in the cat: The FAT CAT study." Journal of Veterinary Cardiology, 2015;17(Suppl 1):S306–S317.
  • Boswood, A., Häggström, J., Gordon, S.G., et al. "Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study — A Randomized Clinical Trial." Journal of Veterinary Internal Medicine, 2016;30(6):1765–1779.
  • ASPCA Animal Poison Control Center. Toxicology and Poison Management Guidelines. American Society for the Prevention of Cruelty to Animals. https://www.aspca.org/pet-care/animal-poison-control

Regulatory & approvals

  • Central Drugs Standard Control Organisation (CDSCO), Government of India. Veterinary Drug Approval Registry, 1969–2026. Directorate General of Health Services. https://cdsco.gov.in/

Databases

  • Washington State University, College of Veterinary Medicine. Veterinary Clinical Pharmacology Laboratory (VCPL) — MDR1 Multidrug Sensitivity Database. https://vcpl.vetmed.wsu.edu/
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →