CUSTOM DERMATOLOGY SEARCH:
Butenafine: An Update of Its Use in Superficial Mycoses
A. K. Gupta MD, PhD, FRCPC
Topical butenafine (Mentax®, Bertek Pharmaceuticals) is approved in the US for the treatment of tinea pedis interdigitalis, tinea corporis, tinea cruris, and in August 2001, this drug was approved by the US FDA for the treatment of pityriasis versicolor, a superficial fungal infection caused by Malassezia spp.
Mechanism of Action
Butenafine hydrochloride is a synthetic benzylamine derivative with a mode of action similar to that of the allylamine class of antifungal drugs. Like the allylamines, butenafine inhibits the fungal enzyme squalene epoxidase, thereby blocking the biosynthesis of ergosterol, which is an essential component of fungal cell membranes.
In Vitro Activity
In certain concentrations and against susceptible organisms, such as dermatophytes, butenafine is thought to be fungicidal.1 Butenafine hydrochloride is active in vitro against many species of fungi, including Trichophyton rubrum, T. mentagrophytes, T. tonsurans, Epidermophyton floccosum, Microsporum canis, and yeasts including C. parapsilosis, C. albicans, and Malassezia spp.
Tinea Pedis 2-4
Butenafine applied once daily for 4 weeks or twice daily for 1 week is effective in the treatment of interdigital tinea pedis. In a multicenter, randomized, double-blind, placebocontrolled study the effectiveness of a once-daily application of butenafine for 4 weeks in the management of interdigital tinea pedis was evaluated.2 At week 4, the mycologic cure rates (negative light microscopy and culture) in the butenafine and vehicle groups were 91% and 63%, respectively (P<0.01). Four weeks following the discontinuation of therapy, the mycologic cure rates in the two groups were 83% and 38%, respectively (P<0.001).
A multicenter, randomized, vehicle controlled, doubleblind trial evaluated the efficacy of butenafine 1% cream applied once daily for 2 weeks in the treatment of tinea corporis.8 Efficacy was evaluated in 78 patients (42 butenafine, 36 vehicle). The mycologic cure (negative KOH and culture) was higher in the butenafine group compared to the vehicle group on day 7 (64% vs. 9%, P<0.001) and day 14 (88% compared to 28% of the vehicle group (P<0.0001). At week 4, following completion of therapy, the butenafine group continued to demonstrate a high mycologic cure rate (88%) compared to a decrease in cure rate in the vehicle group to 17% (P<0.0001). At day 14, the overall cure (mycological cure plus 100% clinical remission) in the butenafine group was 31% compared to 3% in the vehicle group (P=0.001). At the week 4 followup point, the overall cure in the butenafine and vehicle groups was 67% and 14%, respectively (P<0.0001).
In a multicenter, randomized, vehicle-controlled, doubleblind trial, butenafine 1% cream was applied once daily for 2 weeks.9 The mycologic cure (negative KOH and culture) was higher in the butenafine group compared to placebo as early as day 7. The higher efficacy rate in the allylamine group increased during the 2-week period of active treatment. At the 4-week follow-up point, the mycologic cure rate in the butenafine group was 81% compared to 13% in the vehicle group (P<0.0001). At the end of treatment, the overall cure rate (negative mycology and clinical cure) was 32% in the butenafine group compared to 8% in the vehicle group (P<0.01). At 4 weeks post-treatment, overall cure was achieved in 62% of the butenafine, versus a decrease to 3% for the vehicle group (P< 0.0001).
While Malassezia yeasts are normal skin commensals, in some individuals the yeasts transform to a pathogenic, hyphal form, resulting in pityriasis versicolor. In two randomized, controlled trials butenafine and vehicle were applied once daily for two weeks in patients with pityriasis versicolor. In the first study, at 6 weeks post-treatment, 55% of patients receiving butenafine were mycologically cured and 51% were completely cured (i.e., negative mycology and no erythema, scaling or pruritus.). The corresponding numbers for the vehicle group were 36% and 36%, respectively. In the second study, "effective treatment" was defined as negative mycology plus a score of one or less on a 4 point scale (0 to 3) for erythema, pruritus and scaling. At 6 weeks follow-up, 43% of butenafine patients were considered to be effectively treated, versus 26% of the vehicle group.10
In controlled clinical trials, 9 of 815 patients (approx. 1%) treated with butenafine cream 1% reported adverse reactions related to the skin.10 These reactions included burning/stinging of the skin and worsening of the dermatosis. No patients discontinued therapy due to an adverse event. Two of 624 patients receiving the vehicle discontinued therapy because of treatment site related events including severe burning/stinging and itching.10 In uncontrolled trials, the adverse events most commonly associated with the use of butenafine 1% cream included contact dermatitis, erythema, irritation, and itching, with each occurring in less than 2% of patients.10
Dosage and Administration
Butenafine cream 1% is indicated in the US for the topical treatment of interdigital tinea pedis, tinea corporis, and tinea cruris due to T. rubrum, T. tonsurans, T. mentagrophytes, and E. floccosum. In tinea pedis interdigitalis, butenafine cream 1% may be applied twice daily for 7 days or once daily for 4 weeks. In patients with tinea corporis and tinea cruris, it is indicated for once daily application for 2 weeks. For the treatment of pityriasis versicolor, butenafine cream 1% should be applied once daily for 2 weeks.
Dr. Gupta wishes to thank Colin Rule, HBSc for his help with this manuscript.
In this issue:
All content ©2005-2012 SkinThearpyLetter® |
Last modified: Thursday, 20-Feb-2014 18:01:37 MST