Usefulness and pharmacokinetic study of oral terbinafine for hyperkeratotic type tinea pedis

To study and establish an optimal administration method of oral antifungal, terbinafine (TBF), for hyperkeratotic type tinea pedis, from the pharmacokinetic point of view, 20 patients with hyperkeratotic type tinea pedis were given TBF 125 mg once daily for 4 weeks and observed over time for improvement in dermatological symptoms and mycological efficacy. Targeting five of the patients, TBF concentration in the stratum corneum was measured using the liquid chromatography/tandem mass spectrometry (LC-MS/MS) method. TBF was detected in the stratum corneum of the sole 1 week after beginning the treatment in some cases and reached its peak 1 week after the completion of the treatment with a concentration of 247.8 ng g(-1), which was approximately more than 50 times higher than its minimal inhibitory concentration against dermatophytes. TBF was not detected at 8 weeks post-treatment, although its concentration was 50.73 ng g(-1) at 6 weeks post-treatment. Its effectiveness rate (effective + markedly effective) was 95% (19/20) with no adverse reactions, including abnormal changes in the laboratory test values, in any patient. These results suggest that TBF is a useful drug to treat hyperkeratotic tinea pedis from the pharmacokinetic point of view.