Itraconazole penetrates the nail via the nail matrix and the nail bed—an investigation in onychomycosis

Nail-matrix kinetics were studied in 21 patients (19 with onychomycosis, two with tinea corporis) as soon as taking itraconazole (Sporanox) 100 mg daily for up to 7 months. Itraconazole was detected in the distal nail as soon as 1 month after the start of therapy (42 ng/g in fingernails and 16 ng/g in toenails). During the course of treatment, this concentration rose and reached a mean of 160 ng/g in fingernail clippings and 197 ng/g in toenail clippings. Moreover, in fingernails of 12 out of 21 patients and in toenails of six out of 20 patients, itraconazole was detected in the distal nail clippings before full outgrowth of the fastest-growing nail. In most patients, itraconazole was detected in the distal nail clippings earlier than would be expected if the drug were incorporated only via the nail matrix, indicating that in addition to the nail matrix, a second route of penetration into the nail exists, i.e. the nail bed.