Systemic exposure to butenafine is low after topical administration of Mentax®

AbstractButenafine HCl, a fungicidal agent of the benzylamine class, was applied to the skin of normal volunteers once daily for 14 consecutive days as a 1% cream formulation (Mentax®). The doses used were approximately 2 to 20 times higher than normal therapeutic doses. Systemic exposure to butenafine was monitored by measuring levels of butenafine and selected metabolites in the plasma and urine during and after the exposure period. Plasma levels of butenafine and its M-2 metabolite were low following repeated 20-g or 6-g doses. The highest combined plasma level for butenafine and M-2 was less than 11 ng/ml, and plasma levels were proportional to the dose administered. The total amount of butenafine and three of its metabolites (M-1, M-2 and M-3) in the urine represented a very small fraction of the applied dose (0.004-0.008%). These data suggest that topical administration of Mentax® does not result in appreciable systemic exposure to butenafine.Key Words: ButenafineMentax