Enilconazole — Veterinary Vademecum Drug Reference

Dosage & Administration Guidelines

Species	Route	Dose	Frequency	Duration & Clinical Notes
Dog	Topical (shampoo or rinse)	Dilute to 0.2% (2 mg/mL) solution	Every 3-4 days	Duration: 4-8 weeks or until negative fungal cultures Notes: For dermatophytosis, clip hair and remove crusts before application. For nasal aspergillosis, use 1% solution infused into the frontal sinuses under anesthesia.
Dog	Intranasal (infusion)	1% solution (10 mg/mL)	Single or repeated infusion	Duration: As per protocol Notes: Administered under general anesthesia with the animal positioned to allow contact with the fungal plaques.
Cat	Topical (shampoo or rinse)	Dilute to 0.2% (2 mg/mL) solution	Every 3-4 days	Duration: 4-8 weeks or until negative fungal cultures Notes: For dermatophytosis, clip hair and remove crusts before application. Avoid contact with eyes and mucous membranes.
Horse	Topical (spray or rinse)	0.2% solution (2 mg/mL)	Every 3-4 days	Duration: 4-6 weeks Notes: For dermatophytosis, clip hair and remove crusts. For nasal aspergillosis, use 1% solution infused into the sinuses.
Cattle	Topical (spray or rinse)	0.2% solution (2 mg/mL)	Every 3-4 days	Duration: 4-6 weeks Notes: For dermatophytosis, clip hair and remove crusts. Observe withdrawal times for meat and milk.
Small Ruminants	Topical (spray or rinse)	0.2% solution (2 mg/mL)	Every 3-4 days	Duration: 4-6 weeks Notes: For dermatophytosis, clip hair and remove crusts.
Rabbit	Topical (rinse)	0.2% solution (2 mg/mL)	Every 3-4 days	Duration: 4-6 weeks Notes: For dermatophytosis, clip hair and remove crusts. Avoid ingestion.
Bird/Poultry	Topical (spray)	0.2% solution (2 mg/mL)	Every 3-4 days	Duration: 4-6 weeks Notes: For dermatophytosis, clip feathers and remove crusts. Use with caution in small birds.
Exotic/Other	Topical (rinse or spray)	0.2% solution (2 mg/mL)	Every 3-4 days	Duration: 4-6 weeks Notes: For dermatophytosis, clip hair/feathers and remove crusts. Adjust based on species and condition.

Clinical Indications & Species Uses

General Indications

Topical treatment of superficial fungal infections caused by susceptible dermatophytes and Malassezia

Dog (Canine)

Treatment of dermatophytosis (ringworm) caused by Microsporum canis, Microsporum gypseum, and Trichophyton mentagrophytes
Treatment of Malassezia dermatitis
Treatment of nasal aspergillosis (as a topical infusion)

Cat (Feline)

Treatment of dermatophytosis (ringworm) caused by Microsporum canis
Treatment of Malassezia dermatitis

Horse (Equine)

Treatment of dermatophytosis (ringworm)
Treatment of nasal aspergillosis (as a topical infusion)

Cattle (Bovine)

Treatment of dermatophytosis (ringworm)
Treatment of bovine trichophytosis

Small Ruminants (Sheep / Goat)

Treatment of dermatophytosis (ringworm)

Rabbit & Small Mammals

Treatment of dermatophytosis (ringworm)

Avian & Poultry

Treatment of dermatophytosis (ringworm) in some avian species

Exotic & Other Species

Treatment of dermatophytosis in various exotic animals (e.g., reptiles, small mammals)

Pharmacology & Mechanism of Action

Drug Class: Antifungal | Pharmacological Group: Imidazole derivative

Mechanism of Action: Enilconazole is an imidazole antifungal that inhibits the synthesis of ergosterol, a vital component of the fungal cell membrane. It binds to the cytochrome P450 enzyme lanosterol 14α-demethylase, blocking the conversion of lanosterol to ergosterol. This leads to increased membrane permeability, leakage of cellular contents, and ultimately fungal cell death. It is primarily fungistatic but can be fungicidal at high concentrations.

Pharmacodynamics: Enilconazole exhibits broad-spectrum antifungal activity against dermatophytes (e.g., Microsporum, Trichophyton), Malassezia, and some molds. It is effective against both superficial and systemic mycoses. Its activity is concentration-dependent, and it is often used topically for localized infections. In some species, it also has activity against certain Gram-positive bacteria.

⚡ Pharmacokinetics Summary

Absorption: When applied topically, systemic absorption is minimal. Oral absorption is variable and generally poor in most species; however, in some species like dogs, oral administration may result in detectable plasma levels. Inhaled or intranasal administration may result in local absorption.

Distribution: Due to its lipophilic nature, enilconazole distributes well into tissues, including skin, hair, and sebaceous glands. It crosses the blood-brain barrier to a limited extent. In systemic use, it is widely distributed in body tissues.

Metabolism: Enilconazole is extensively metabolized in the liver via oxidation and conjugation. Multiple metabolites are formed, some of which may retain antifungal activity.

Excretion: Metabolites are primarily excreted in the feces via bile, with a smaller amount in urine. In lactating animals, small amounts may be excreted in milk.

Half-Life: The half-life varies by species and route. In dogs, after oral administration, the half-life is approximately 6-8 hours. In cattle, after topical application, systemic levels are low, and the half-life is not well defined.

Bioavailability: Oral bioavailability is low and variable (approximately 20-30% in dogs). Topical bioavailability is negligible systemically.

Protein Binding: Enilconazole is highly protein-bound (approximately 90%) in plasma.

Available Formulations & Strengths

Topical Solution (concentrate) 10% (100 mg/mL) concentrate for dilution (Topical)

Topical Spray 0.2% (2 mg/mL) ready-to-use (Topical)

Shampoo 0.2% (2 mg/mL) (Topical)

Powder for topical use Various (Topical)

Contraindications & Clinical Warnings

Contraindications:

Hypersensitivity to enilconazole or other imidazole antifungals
Do not use in animals with known hepatic impairment (for systemic use)
Do not apply to open wounds or broken skin (topical)
Do not use in pregnant animals unless benefits outweigh risks (limited safety data)
Do not use in animals intended for breeding without veterinary assessment

Warnings & Clinical Precautions:

For topical use only unless otherwise directed; avoid ingestion and contact with eyes and mucous membranes
Wear gloves when applying to animals to avoid skin sensitization
Do not use in animals with known hypersensitivity to imidazoles
Use with caution in animals with hepatic disease (systemic use)
In food animals, observe withdrawal times
In horses, avoid use in pregnant mares unless clearly necessary
In cats, use with caution as they may be more sensitive to imidazole toxicity
Do not use in animals with known hypersensitivity to imidazoles
Use with caution in animals with hepatic disease (systemic use)
In food animals, observe withdrawal times
In horses, avoid use in pregnant mares unless clearly necessary
In cats, use with caution as they may be more sensitive to imidazole toxicity

Adverse Effects & Reactions

Common:

Local skin irritation (redness, itching) at application site
Transient stinging or burning sensation
Hair discoloration at application site

Serious / Severe:

Hepatotoxicity (with systemic use)
Neurological signs (ataxia, tremors) with high systemic absorption
Allergic reactions (urticaria, angioedema)

Rare:

Bone marrow suppression (with prolonged systemic use)
Endocrine disturbances (due to enzyme inhibition)

Key Drug Interactions

Interacting Drug / Class	Clinical Effect & Mechanism	Severity
CYP450 enzyme inhibitors (e.g., cimetidine, ketoconazole)	May increase enilconazole plasma levels and risk of toxicity	Moderate
CYP450 enzyme inducers (e.g., phenobarbital, rifampin)	May decrease enilconazole efficacy by increasing metabolism	Moderate
Warfarin and other anticoagulants	Enilconazole may enhance anticoagulant effect (inhibition of metabolism)	Moderate
Amphotericin B	Potential antagonism of antifungal effect (azole vs. polyene)	Mild

Overdose & Toxicity Management

Signs of Toxicity:

Vomiting
Diarrhea
Ataxia
Tremors
Hepatotoxicity (with systemic absorption)
Respiratory depression (in severe cases)

Emergency Treatment Protocol: There is no specific antidote. Treatment is symptomatic and supportive. Induce emesis if recent oral ingestion and animal is conscious. Administer activated charcoal to reduce absorption. Provide intravenous fluids, monitor liver enzymes, and manage neurological signs with anticonvulsants if necessary. For topical overdose, wash the area thoroughly with mild soap and water.

Food Animal Withdrawal Times

🥩 Meat: 7 days🥛 Milk: 0 days

Withdrawal times may vary by country and formulation. For cattle, meat withdrawal is typically 7 days; milk withdrawal is zero if used topically, but systemic use may require longer. For poultry, egg withdrawal is not established; consult local regulations.

Storage, Handling & Regulatory Information

Storage Temperature: Store at room temperature (15-30°C / 59-86°F)

Light Sensitivity: Light-sensitive — protect from direct exposure.

Handling & Special Conditions: Protect from light and moisture. Keep container tightly closed. Do not freeze.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Not FDA-approved for veterinary use in the US; available as a compounded product or imported.

Extra-Label (Off-Label) Use: In the US, enilconazole is not FDA-approved for veterinary use; it may be used under AMDUCA (Animal Medicinal Drug Use Clarification Act) for extralabel use in animals. In some countries, it is approved for topical use in dogs, cats, and horses. For food animals, extralabel use is prohibited if it results in violative residues.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Enilconazole is a valuable topical antifungal for treating dermatophytosis and Malassezia infections in various species. It is often used as a rinse or shampoo, and dilution is critical to avoid irritation. For nasal aspergillosis in dogs and horses, it is used as an intranasal infusion under anesthesia. Systemic absorption is minimal with topical use, making it relatively safe, but caution is needed in animals with hepatic disease. In food animals, withdrawal times must be observed. Due to lack of FDA approval, use is often extralabel, and veterinary oversight is essential. Always confirm the diagnosis and perform fungal cultures to monitor treatment efficacy.

References & Literature

📚 Plumb's Veterinary Drug Handbook
📚 Papich Veterinary Pharmacology and Therapeutics
📚 Compendium of Veterinary Products (CVP)