What is the recommended treatment for dermatophytosis?

Treatment of Dermatophytosis

The recommended treatment for dermatophytosis should be tailored to the specific type of infection, with oral terbinafine being the first-line therapy for most dermatophyte infections due to its superior efficacy, fungicidal action, and lower relapse rates compared to other antifungals. 1

Treatment Algorithm Based on Infection Site

Tinea Unguium (Onychomycosis)

• First-line: Oral terbinafine 250 mg daily
  • Fingernail infections: 6 weeks 2
  • Toenail infections: 12-16 weeks 2, 1
• Alternative: Itraconazole 200 mg daily continuously for 12 weeks or pulse therapy (400 mg daily for 1 week per month) 1
  • Two pulses for fingernail infections
  • Three pulses for toenail infections 3

Tinea Capitis

• For Microsporum species: Griseofulvin (15-20 mg/kg/day for <50 kg, 1g/day for >50 kg) for 6-8 weeks 3
• For Trichophyton species: Terbinafine based on weight for 2-4 weeks 3
  • <20 kg: 62.5 mg/day
  • 20-40 kg: 125 mg/day

  • 40 kg: 250 mg/day

Tinea Corporis/Cruris/Pedis

• Localized infections: Topical antifungals 4
  • Terbinafine 1% cream once or twice daily for 1-2 weeks 5
  • Azoles (clotrimazole, miconazole) twice daily for 2-4 weeks
• Extensive/Severe/Resistant infections: Oral therapy 4
  • Terbinafine 250 mg daily for 2-4 weeks
  • Itraconazole 200 mg daily for 1-2 weeks

Important Considerations

Pre-treatment Assessment

• Confirm diagnosis with appropriate laboratory testing (KOH preparation, fungal culture, or biopsy) before initiating treatment 2, 6
• Baseline liver function tests and complete blood count recommended for patients with:
  • History of heavy alcohol consumption
  • Pre-existing liver disease
  • Hepatitis
  • Hematological abnormalities 3, 1

Monitoring and Follow-up

• Re-evaluate 3-6 months after treatment initiation for onychomycosis 3
• Consider additional treatment if infection persists
• Monitor for adverse effects, particularly:
  • Hepatotoxicity (nausea, anorexia, fatigue, vomiting, abdominal pain, jaundice) 2
  • Taste disturbance (can be severe and potentially permanent) 2
  • Smell disturbance 2
  • Depressive symptoms 2

Contraindications

• Terbinafine: Active or chronic liver disease, history of allergic reaction 2
• Griseofulvin: Lupus erythematosus, porphyria, severe liver disease 3

Drug Interactions

• Terbinafine: Minimal drug interactions, primarily with drugs metabolized by cytochrome P450 2D6 3
• Griseofulvin: Decreased plasma concentration with rifampicin, increased with cimetidine 3

Treatment Efficacy Considerations

Terbinafine has demonstrated superior efficacy compared to other antifungals:

• Higher mycological cure rates (>80%) for dermatophyte infections 7
• More effective than continuous or intermittent itraconazole in dermatophyte onychomycosis 7
• Greater efficacy than griseofulvin in dermatophyte onychomycosis, tinea pedis, and tinea corporis/cruris 7
• Shorter treatment duration required compared to azoles 1

Common Pitfalls to Avoid

1. Failure to confirm diagnosis: Always obtain appropriate specimens for laboratory testing before initiating treatment 2, 6
2. Inadequate treatment duration: Complete the full course of therapy even if symptoms improve early
3. Overlooking drug interactions: Consider potential interactions, especially with itraconazole
4. Ignoring concomitant infections: Treat any associated tinea pedis to prevent reinfection 1
5. Not addressing treatment failure: Consider factors such as poor compliance, poor absorption, immunosuppression, or resistance 1

By following this treatment algorithm and considering these important factors, clinicians can effectively manage dermatophytosis and improve patient outcomes.