Vet’s 2025 Guide to Itraconazole (Itrafungol™) in Horses – by Dr Duncan Houston

💊 Vet’s 2025 Guide to Itraconazole (Itrafungol™) in Horses

By Dr Duncan Houston BVSc

1. What Is Itraconazole?

Itraconazole is a broad-spectrum **triazole antifungal** commonly used in veterinary medicine as an oral solution (Itrafungol™) or capsule. While labeled for cats, it’s also prescribed **off-label** for horses to treat fungal infections like aspergillosis, keratomycosis, and systemic mycoses.

2. Pharmacokinetics & Formulations

• Oral solution (with cyclodextrin) shows better bioavailability (~65%) than capsules (~12%).
• Study in horses: 5 mg/kg PO yielded plasma ~0.41 μg/mL, long half-life (~11 h), high protein binding.
• Itraconazole distributes widely but may not reach interstitial fluid or eye at full concentration.

3. Indications in Horses

• **Ulcerative keratomycosis (eye fungus):** 1% topical itraconazole every 1–2 h, often with oral drug 5 mg/kg daily.
• **Nasal aspergillosis/mycosis:** oral itraconazole shown effective in small case studies.
• **Systemic mycoses** (e.g., blastomycosis, cryptococcosis): dosage extrapolated from fluconazole (5 mg/kg q24 h); itraconazole often more effective for Aspergillus.

4. Recommended Dosing

The solution is preferred for consistent absorption; capsules may be cost-prohibitive and less effective.

5. Safety & Side Effects

• Generally well-tolerated; monitor **liver enzymes** as azoles can cause hepatic stress.
• Pregnant mares: **contraindicated**, may cause fetal harm.
• Drug interactions: inhibits cytochrome P450—avoid with macrolides, H₂ blockers, proton-pump inhibitors.

6. Monitoring During Therapy

• Check **baseline** and periodic serum chemistry (ALT, AST, GGT).
• Assess clinical progress at 2–4-week intervals—improvement should be gradual.
• Ophthalmologic or nasal follow-up as needed (e.g., imaging, fungal cultures).

7. Treatment Duration

Courses last **4–12 weeks**, depending on infection severity and location. Continue treatment at least 2 weeks after lesion resolution or negative culture.

8. Practical Tips for Use

• Administer oral solution on an **empty stomach** for better absorption; capsules with food.
• Use the built-in syringe for accuracy; ensure horses accept the taste (cherry/caramel flavored).
• Don’t use compounded forms—poor bioavailability.
• Handle solution carefully—wear gloves to avoid human exposure.

9. Emergency & Contraindications

• Avoid use in **pregnant/lactating mares** and horses with hepatic disease.
• Contraindicated in known hypersensitivity to azoles.
• Caution when co-administering with medications modifying stomach pH or hepatic metabolism.

10. Ask A Vet Support 🩺

At Ask A Vet, we help you by:

• Selecting the right form and dose for your horse
• Setting up monitoring schedules (bloodwork, clinical follow-up)
• Managing side effects or drug interactions
• Coordinating multidisciplinary care with ophthalmologists or internists
• Ensuring compliance with infection clearance and retreatment needs

Download the Ask A Vet app today for personalized antifungal therapy support in 2025! ❤️

11. Quick Reference Table

12. Final Thoughts

Itraconazole is a valuable off-label antifungal in equine medicine when used thoughtfully—solution over capsules, proper dosing, and careful monitoring are key. With Ask A Vet’s guidance, you can navigate therapy confidently and ensure your horse recovers safely. 🐴