indication

For the topical treatment of the following dermatologic infections: tinea (pityriasis) versicolor due to M. furfur, interdigital tinea pedis (athlete’s foot), tinea corporis (ringworm) and tinea cruris (jock itch) due to E. floccosum, T. mentagrophytes, T. rubrum, and T. tonsurans.

pharmacology

Butenafine is a synthetic antifungal agent that is structurally and pharmacologically related to allylamine antifungals. The exact mechanism of action has not been established, but it is suggested that butenafine's antifungal activity is exerted through the alteration of cellular membranes, which results in increased membrane permeability, and growth inhibition. Butenafine is mainly active against dermatophytes and has superior fungicidal activity against this group of fungi when compared to that of terbinafine, naftifine, tolnaftate, clotrimazole, and bifonazole. It is also active against Candida albicans and this activity is superior to that of terbinafine and naftifine. Butenafine also generates low MICs for Cryptococcus neoformans and Aspergillus spp. as well.

mechanism of action

Although the mechanism of action has not been fully established, it has been suggested that butenafine, like allylamines, interferes with sterol biosynthesis (especially ergosterol) by inhibiting squalene monooxygenase, an enzyme responsible for converting squalene to 2,3-oxydo squalene. As ergosterol is an essential component of the fungal cell membrane, inhibition of its synthesis results in increased cellular permeability causing leakage of cellular contents. Blockage of squalene monooxygenase also leads to a subsequent accumulation of squalene. When a high concentration of squalene is reached, it is thought to have an effect of directly kill fungal cells.

biotransformation

The primary metabolite in urine was formed through hydroxylation at the terminal t-butyl side-chain.

absorption

The total amount absorbed through the skin into the systemic circulation has not been quantified.

half life

Following topical application, a biphasic decline of plasma butenafine concentrations was observed with the half-lives estimated to be 35 hours initial and over 150 hours terminal.