Miconazole
Miconazole is a broad-spectrum **imidazole antifungal** agent used primarily for the topical treatment of fungal skin and ear infections, including **dermatophytosis** (ringworm) and **Malassezia dermatitis**. It is frequently formulated in combination with other agents (such as chlorhexidine, corticosteroids, or antibiotics) to provide synergistic effects in treating otitis externa and pyoderma. > **Clinical Pearl:** While highly effective topically, miconazole is rarely used systemically in veterinary medicine due to potential toxicity and the availability of safer systemic alternatives like itraconazole or fluconazole.
Mecanismo: Miconazole works by inhibiting the **cytochrome P450-dependent enzyme 14-alpha-demethylase** in fungal cells. Inhibition of 14-alpha-demethylase → depletion of **ergosterol** (a vital component of the fungal cell membrane) → accumulation of toxic sterol precursors → increased cell wall permeability → leakage of cellular contents and subsequent fungal cell death. It has potent activity against *Malassezia*, *Cryptococcus*, *Candida*, and *Coccidioides*.
Dosificación por especie
- Fungal otitis · 2-12 drops in affected ear · topical · q12-24h · Surolan formulation
- Fungal otitis · 1 ml per ear · topical · q24h · 5 days · Easotic formulation
- Fungal otitis · 5 drops in affected ear · topical · q12h · Aurimic formulation
- Dermatophytosis · Apply a thin layer of cream topically to affected area · topical · bid · Continue for 2 weeks after a clinical cure and negative fungal cultures · Daktarin formulation
- Malassezia dermatitis · Shampoo twice weekly until the clinical signs subside and weekly thereafter or as necessary · topical · twice weekly · Until clinical signs subside, then weekly · Malaseb, Adaxio formulations
- Small localized skin infections · Apply a few drops to affected skin · topical · q12h · Aurimic formulation
- Fungal otitis · 2-12 drops in affected ear · topical · q12-24h · Surolan formulation
- Fungal otitis · 1 ml per ear · topical · q24h · 5 days · Easotic formulation
- Fungal otitis · 5 drops in affected ear · topical · q12h · Aurimic formulation
- Dermatophytosis · Apply a thin layer of cream topically to affected area · topical · bid · Continue for 2 weeks after a clinical cure and negative fungal cultures · Daktarin formulation
Vías de administración
Contraindicaciones
- Hypersensitivity to miconazole or other azole antifungals
- Ruptured tympanic membrane (for certain otic preparations)
Efectos adversos
- Local irritation
- Erythema
- Pruritus (rare)
Monitoreo
- Resolution of clinical signs (pruritus, erythema, scaling)
- Fungal cultures (for dermatophytosis)
- Cytology (for Malassezia)
Sobredosis
Overdose is highly unlikely with topical administration. Accidental ingestion of shampoos or creams may cause mild gastrointestinal upset (hypersalivation, vomiting, diarrhea). Treatment is symptomatic and supportive.
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