Terbinafine hydrochloride is a synthetic allylamine derivative structurally related to naftifine, antifungal terbinafine hydrochloride blocks ergosterol biosynthesis by inhibition ofsqualene epoxidase, part of the sterol synthesis pathway for the fungal cell membrane. Highly lipophilic, it tends to accumulate in skin, nails, and fatty tissues. Terbinafine is active against dermatophytes.