Terbinafine

Snapshot

• A 5-year-old boy is brought to the pediatrician for evaluation of hair loss. His mother reports that this has been going on for a week, and her son continues to scratch the areas of baldness. His uncle has alopecia areata, and his mother is worried that the patient has the same disease. Physical exam reveals patches of alopecia with scale and erythema. A potassium hydroxide preparation shows fungal hyphae. He is prescribed an oral medication, as a topical formulation of this drug will not penetrate into the hair follicles. (Tinea capitis)

Introduction

• Drugs
  • terbinafine
    • topical or systemic
• Mechanism of action
  • inhibits fungal squalene epoxidase 
    • inhibits biosynthesis of lanosterol, a precursor to ergosterol, which is a key component of the cell membrane
  • cleared via hepatic metabolism
• Clinical use
  • dermatophyte infections
  • onychomycosis
  • paracoccidioidomycosis
  • seborrheic dermatitis
• Adverse effects
  • hepatotoxicity 
    • contraindicated in liver disease
  • taste disturbance
  • gastrointestinal upset