Butenafine Hydrochloride

Butenafine hydrochloride is a benzylamine derivative with potent fungicidal activity against dermatophytes, including *Trichophyton* and Microsporum species. It inhibits squalene epoxidase, blocking ergosterol synthesis and disrupting the fungal cell membrane. The drug penetrates well into the epidermis and has a long skin retention time of up to 72 hours, providing residual therapeutic effects. Topical 1% butenafine cream is highly effective for tinea pedis, tinea cruris, and tinea corporis, with once-daily application for one to four weeks. Cure rates continue to improve after treatment cessation. Preliminary efficacy is also seen against pityriasis versicolor and seborrheic dermatitis. Butenafine is well tolerated, with mild local burning or stinging in a small number of patients.

Fig. 1 Double blind vehicle controlled randomized trials of butenafine. (Singal A. 2008)

A microemulsion-loaded hydrogel of butenafine hydrochloride (BTF) was designed to overcome poor water solubility and low skin penetration. Isopropyl palmitate, aerosol OT, and sorbitan monooleate were selected as the oil, surfactant, and co-surfactant. Pseudoternary phase diagrams identified optimal microemulsion compositions. The optimized microemulsion had a droplet size of 142.15 nm and a zeta potential of −45 mV. Among three gel bases, Carbopol 940 gel showed the best spreadability, viscosity, and stability without disrupting the microemulsion structure. Antifungal assays against Candida albicans showed larger inhibition zones. Histopathology confirmed enhanced skin permeation and stratum corneum disruption. The formulation was non-irritant in rabbit skin tests. The microemulsion-loaded Carbopol 940 gel significantly improved BTF penetration and antifungal activity over conventional cream.