Descriptive correlations between various doses of oral terbinafine and concentrations in nail

In order to plan optimum drug regimens for the treatment of onychomycosis with terbinafine, it is necessary to have information concerning the pharmacokinetics of terbinafine in the nail plate. A group of 24 patients with mycology culture-positive onychomycosis took 125, 250 or 500 mg terbinafine once daily for 16 weeks in a double-blind parallel-group study. Distal nail clippings, proximal nail samples and blood samples were taken at frequent intervals during therapy and during a follow-up of up to 36 weeks. Of the 24 patients, 17 completed the study. There was an apparent dose response with regard to concentration of terbinafine and its main metabolite demethylterbinafine in the distal and proximal part of affected nails as well as in plasma. The length of time during which terbinafine could be detected after stopping treatment increased with increasing dosage. The results suggest that short-term therapy with the higher dosage regimens is likely to have a higher efficacy rate.