Terbinafine Levels in Serum, Stratum Corneum, Dermis-Epidermis, Hair, Sebum, and Eccrine Sweat

The study measured terbinafine levels in various tissues and fluids of volunteers taking 250 mg doses daily. Terbinafine rapidly concentrated in the stratum corneum (up to 9.1 µg/g) and sebum (up to 45.1 µg/ml), with hair concentrations reaching 2.6 µg/g, indicating high levels around hair follicles. It was not detected in sweat, and plasma levels ranged from 0.1 to 1.0 µg/ml. The drug accumulated tenfold in the stratum corneum by day 2 and had a tissue elimination half-life of 4-5 days, maintaining fungicidal levels for over 3 weeks. Terbinafine's pharmacokinetics were similar to itraconazole but differed from ketoconazole and griseofulvin, achieving higher and longer-lasting levels.