Abstract
Ungual formulations are regularly tested using human nails or animal surrogates in Franz diffusion cell experiments. Membranes sometimes less than 100 µm thick are used, disregarding the higher physiological thickness of human nails and possible fungal infection. In this study, bovine hoof membranes, healthy or infected with Trichophyton rubrum, underwent different imaging techniques highlighting that continuous pores traversed the entire membrane and infection resulted in fungal growth, both superficial, as well as in the membrane’s matrix. These membrane characteristics resulted in substantial differences in the permeation of the antifungal model substance bifonazole, depending on the dosage forms. Increasing the thickness of healthy membranes from 100 µm to 400 µm disproportionally reduced the permeated amount of bifonazole from the liquid and semisolid forms and allowed for a more pronounced assessment of the effects by excipients, such as urea as the permeation enhancer. Similarly, an infection of 400-µm membranes drastically increased the permeated amount. Therefore, the thickness and infection statuses of the membranes in the permeation experiments were essential for a differential readout, and standardized formulation-dependent experimental setups would be highly beneficial.
Highlights
IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
The commercial products CRE and Salbe with (SAL) were chosen for further investigation in this arrangement to best mimic actual use conditions, where the application of SAL is recommended for two weeks prior to application of CRE to evaluate whether the infected model would maintain the observed differences in the healthy setup, supporting this recommendation
Bovine hoof sheets have rightfully been established as a surrogate for human nails in in vitro test systems, as they allow for rather physiological, yet still sufficiently fast, assessments of permeation characteristics of typically employed formulations, most of all lacquers
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Almost five percent of the North American and European population is affected by fungal nail infection, mainly occurring on the toenails [1]. Such infections are mostly caused by dermatophytes and, to a lesser extent, by yeasts or molds. Trichophyton rubrum (T. rubrum) alone accounts for about 90% of cases overall [2]. Common symptoms, including discoloration, brittleness, and deformation of the nail plate, can affect one’s psychological well-being and, in severe cases, even lead to social isolation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
