What is the recommended dose of Lamisil (terbinafine)?

Recommended Dosage of Lamisil (Terbinafine)

The recommended dose of Lamisil (terbinafine) is 250 mg once daily for 6 weeks in fingernail infections and 250 mg once daily for 12 weeks in toenail infections. 1, 2

Adult Dosing for Onychomycosis

Oral Terbinafine Dosing

• 250 mg once daily for 6 weeks for fingernail infections 1, 2
• 250 mg once daily for 12-16 weeks for toenail infections 1, 2
• For severe toenail infections, some evidence suggests 12 weeks is more effective than 6 weeks of treatment 3, 4

Efficacy Considerations

• Terbinafine is fungicidal against dermatophytes with very low minimum inhibitory concentrations (approximately 0.004 μg/mL) 2
• It has demonstrated superior efficacy compared to itraconazole for dermatophyte onychomycosis, with higher cure rates and lower relapse rates 2, 5
• Mycological cure rates with 12 weeks of terbinafine treatment have been reported as high as 73-81% compared to 45.8-49% with itraconazole 6, 5

Pediatric Dosing

• For children <20 kg: 62.5 mg daily 2
• For children 20-40 kg: 125 mg daily 2
• For children >40 kg: 250 mg daily (adult dose) 2
• Duration: 6 weeks for fingernail and 12 weeks for toenail infections 2

Monitoring Recommendations

• Baseline liver function tests (LFTs) and complete blood count (CBC) are recommended before starting treatment 2, 7
• More vigilant monitoring of LFTs is advised for patients with:
  • Pre-existing liver disease 7
  • Concomitant use of hepatotoxic medications 7
  • Continuous therapy for more than one month 7
  • History of heavy alcohol consumption 7

Contraindications

• History of allergic reaction to oral terbinafine 1
• Active or chronic liver disease 8
• Lupus erythematosus 2, 8

Important Considerations

• Terbinafine has minimal drug interactions compared to azole antifungals 7, 6
• The most significant potential interaction is with drugs metabolized by cytochrome P450 2D6 isoenzyme 7, 1
• Response to treatment should be evaluated 3-6 months after initiation 7
• Common adverse effects include headache, gastrointestinal upset, taste disturbance, and rash 1
• Severe adverse effects that warrant discontinuation include:
  • Liver injury 1
  • Taste or smell disturbance 1
  • Depressive symptoms 1
  • Severe neutropenia (neutrophil count ≤1,000 cells/mm³) 1
  • Serious skin reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis) 1

Treatment Duration Considerations

• Historical studies have confirmed that 12 weeks is the optimal treatment duration for toenail infections, with significantly lower cure rates seen with 6-week regimens 4
• For fingernail infections, 6 weeks of therapy has been shown to be sufficient 3
• Factors that may influence treatment response include shorter duration of disease prior to treatment and non-involvement of the big toenail 3