What is the preferred treatment between terbinafine and itraconazole for fungal infections?

Terbinafine vs Itraconazole for Fungal Infections

Terbinafine is the preferred first-line treatment over itraconazole for dermatophyte fungal infections, particularly onychomycosis, due to its superior mycological cure rates (73-94% vs 45.8%) and lower relapse rates. 1

Comparative Efficacy

• Terbinafine advantages:

  • Higher mycological cure rates (73-94%) compared to itraconazole (45.8%) 1
  • Superior long-term outcomes with lower relapse rates (23% vs 53%) 2
  • Fungicidal (kills fungi) rather than just fungistatic action 2
  • Persists in nail tissue for up to 30 weeks after treatment completion 2

• Dosing regimens:

  • Terbinafine: 250mg once daily for 12 weeks (continuous) 1
  • Itraconazole: 200mg daily for 12 weeks or pulse therapy (400mg daily for 1 week per month) 1

Organism-Specific Considerations

The choice between these agents should be guided by the causative organism:

• For dermatophyte infections (most common nail and skin infections):

  • Terbinafine is clearly superior, especially for Trichophyton species 1
  • The L.I.ON. study demonstrated terbinafine's superiority with approximately twice the mycological cure rate of itraconazole at 72 weeks follow-up (76% vs 38%) 2

• For Candida infections:

  • Itraconazole may be preferred due to better activity against yeasts 3, 4

• For Microsporum infections:

  • Consider alternatives as terbinafine has reduced efficacy 1

Safety and Drug Interactions

• Terbinafine has a better safety profile with fewer drug interactions compared to itraconazole 1, 2
• Terbinafine is preferred in patients on multiple medications, particularly those on antiretrovirals 1
• Both medications are generally well-tolerated with comparable adverse event profiles 4
• Most common side effects for terbinafine are gastrointestinal complaints (10.5% of patients) 2

Special Populations

• HIV patients: Terbinafine preferred due to lower risk of interactions with antiretrovirals 1
• Diabetic patients: Terbinafine preferred due to lower risk of drug interactions 1
• Pediatric patients: Weight-based dosing for terbinafine (62.5mg for <20kg, 125mg for 20-40kg, 250mg for >40kg) 1

Treatment Failures

For recalcitrant cases that fail to respond to monotherapy:

• Recent evidence suggests combination therapy with both terbinafine and itraconazole may be effective for difficult-to-treat dermatophytosis, achieving 90% cure rates compared to 35% with terbinafine alone and 50% with itraconazole alone 5
• Consider this approach for treatment failures or extensive infections

Common Pitfalls to Avoid

• Not confirming diagnosis before initiating treatment (only about half of nail dystrophies are fungal) 1
• Inadequate treatment duration
• Simultaneous use of corticosteroids with antifungals
• Unrealistic expectations about speed of improvement
• Not addressing predisposing factors or implementing preventive measures 1

In conclusion, while both medications are effective, terbinafine demonstrates superior efficacy against dermatophytes with better long-term outcomes and fewer drug interactions, making it the preferred first-line treatment for most fungal infections, particularly onychomycosis.