A 3D-printed diffusion cell for nail permeation testing

Evaluation of nail diffusion of active pharmaceutical ingredients (API) is a challenge but a necessity during pre-clinical studies of antifungals for the treatment of onychomycosis. Nevertheless, available model are expensive or poorly accessible. Thus, a model based on a 3D printable cell and bovine hoof slices was designed. This model was assessed with two Amphotericine B (AmB) based preparations, a gel and a cream. After 7 days diffusion in the 3D printed cell, AmB was extracted from the hooves slices and quantitated by high-performance liquid chromatography (HPLC). Obtained AmB mean concentrations in hooves were 125.9 ± 7.4 µg/cm³ for AmB gel and 95.6 ± 15.9 µg/cm³for AmB cream, with "cm³" referring to hoof thickness multiplied by diffusion surface. To complete the hoof diffusion test in the 3D printed cell, agar diffusion was also performed to access the ability of the API to diffuse through a water based matrix and to keep its antifungal properties. An ungual penetration model, using a 3D printed diffusion cell, that is simple to implement and easily accessible has been developed. Although it cannot produce results directly extendable to humans, it allows the comparison of several semi-solid formulation solutions with each other.