A 31-year-old male farm worker visits the doctor with an itchy rash on his chest. Physical examination reveals a five-centimeter-diameter annular and scaling plaque with central clearing on the chest. KOH preparation of skin scrapings reveals branching septate hyphae, and terbinafine topical application was recommended. Which of the following mechanisms of action explains the antifungal activity of this drug?

Question

Quizplus · Accepted Answer

Eductional Objective: The patient described in this vignette is suffering from tinea corporis. Tinea corporis manifests clinically as an annular scaling plaque with well-defined, raised erythematous borders and central clearing.
Terbinafine is a drug that is commonly used to treat dermatophytosis. It belongs to the allylamine class of antifungals and can be used topically or orally. Terbinafine inhibits fungal membrane ergosterol synthesis by inhibiting the enzyme squalene epoxidase. Ergosterol is a cell membrane sterol found only in fungi and not in human cell membranes. This medication tends to accumulate in the skin and its appendages, and its side effects are mild when administered topically.

A 31-Year-Old Male Farm Worker Visits the Doctor with an Itchy