What is the best treatment for a female patient with onychomycosis (fungal infection of the nail) of the fingernail and tinea corporis (ringworm of the body)?

Treatment for Onychomycosis of Fingernail and Tinea Corporis in Female Patients

Oral terbinafine is the first-line treatment for fingernail onychomycosis (250mg daily for 6 weeks) and should be combined with topical antifungal therapy for tinea corporis. 1, 2

Recommended Treatment Regimen

For Fingernail Onychomycosis:

• Oral terbinafine 250mg once daily for 6 weeks is the treatment of choice for fingernail onychomycosis due to its superior efficacy and tolerability 1, 2
• Terbinafine has demonstrated higher mycological cure rates (80-90% for fingernail infections) compared to other antifungals 1
• Terbinafine is fungicidal against dermatophytes (the most common causative organisms), with a very low minimum inhibitory concentration (MIC) of approximately 0.004 μg/mL 1
• The drug persists in the nail for up to 6 months after completion of treatment, providing continued antifungal activity 1

For Tinea Corporis:

• Topical antifungal preparations (such as terbinafine 1% cream or an imidazole cream) applied twice daily for 1-2 weeks are effective for localized tinea corporis 3
• Topical terbinafine 1% formulations achieve mycological cure in >80% of patients with tinea corporis when applied once or twice daily for up to 2 weeks 3

Evidence Supporting Terbinafine as First-Line Therapy

• Multiple large studies demonstrate higher efficacy rates for terbinafine compared to itraconazole and other antifungals 1
• A multicentre, randomized trial showed complete cure in 55% of patients receiving terbinafine versus 26% with pulsed itraconazole at 72-week follow-up 1
• Long-term follow-up studies show significantly lower relapse rates with terbinafine (23% mycological relapse) compared to itraconazole (53% mycological relapse) 1, 4
• The British Association of Dermatologists guidelines explicitly state that "terbinafine is superior to itraconazole both in vitro and in vivo for dermatophyte onychomycosis and should be considered the first-line treatment" 1

Alternative Treatment Options

If terbinafine is contraindicated:

• Itraconazole is the next best alternative 1
  • For fingernail infection: 200mg daily for 12 weeks continuously, or pulse therapy at 400mg daily for 1 week per month for 2 pulses 1
  • Particularly effective for Candida infections of the nail plate 1
• Fluconazole (though not licensed for onychomycosis) may be considered at 450mg once weekly 1

Important Considerations and Monitoring

• Confirm diagnosis before treatment: Mycological confirmation (KOH preparation, fungal culture, or nail biopsy) should be obtained before initiating systemic therapy 2, 1
• Baseline liver function tests are recommended in patients with:
  • History of heavy alcohol consumption
  • Hepatitis or other liver disease
  • Hematological abnormalities 1
• Monitor for side effects:
  • Gastrointestinal complaints (most common: nausea, diarrhea)
  • Taste disturbance (can be permanent in rare cases)
  • Skin reactions (rash, pruritus, urticaria) 1, 2
• Contraindications for terbinafine:
  • Active or chronic liver disease
  • History of allergic reaction to terbinafine 2

Treatment Success and Follow-up

• Re-evaluate 3-6 months after treatment initiation 1
• Clinical improvement may continue for months after completion of therapy due to the time required for healthy nail outgrowth 2
• In cases of treatment failure, consider:
  • Poor compliance
  • Poor drug absorption
  • Immunosuppression
  • Dermatophyte resistance
  • Subungual dermatophytoma (may require partial nail removal) 1

By following this treatment approach, patients with fingernail onychomycosis and tinea corporis can expect high cure rates with minimal side effects and a lower risk of relapse compared to other antifungal regimens.