Amorolfine 5% Nail Lacquer Exhibits Potent Antifungal Activity Compared to Three Acid-Based Devices Indicated for the Treatment of Onychomycosis: An In Vitro Nail Penetration Assay

INTRODUCTION: Onychomycosis is the most common infectious disease involving nails. The aim of this study was to evaluate the antifungal activity of amorolfine 5% nail lacquer and three different acid-based medical devices indicated in the treatment of onychomycosis using an in vitro nail penetration assay. METHODS: Four products were tested in vitro: (a) amorolfine 5% nail lacquer; (b) ethyl lactate and acetic acid; (c) citric acid and urea; (d) ethyl lactate, glycerin, lactic acid, and citric acid. Test products were applied to healthy human cadaver nails and allowed to dry. Disks were cut from each piece of nail and placed on seeded agar plates of Trichophyton rubrum. Following incubation at 30 °C, zones of inhibition were measured. RESULTS: Amorolfine-treated nails exhibited inhibitory activity against T. rubrum with a mean zone of inhibition of 59.2 mm in diameter. In contrast, all three acid-based medical devices and the untreated controls showed no zones of inhibition (mean effective zones of 0 mm). CONCLUSION: In this in vitro nail penetration model, head-on, comparative study, we showed that amorolfine 5% nail lacquer possesses potent antifungal activity, whereas no antifungal activity was detected for three commercially available acid-based medical devices under identical assay conditions. FUNDING: Galderma. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s13555-016-0093-x) contains supplementary material, which is available to authorized users.