Nail diseases, especially onychomycosis, which contributes to
as much as 50% of nail disorders [1–3], should be efficiently treated
to improve a patient’s quality of life. Unlike skin diseases, for which
medical treatments are continuously developed, treatments of nail
diseases hitherto are not satisfying. The main obstacles are our limited
knowledge of conquering the perfect barrier of the human nail
and the limited source of human nails as the object of the study itself.
Bovine hoof has been accepted until now as a substitute for
human nail, but significant differences between them have been
reported [4]. The limitation of animal hoof as a study object is its
great water uptake during hydration, which could lead to the overestimation
of drug permeability, when this is translated to human
nail. Khengar et al. [4] reported that the water uptake by human
nail was 27 ± 3%, whereas that of horse hoof was 40 ± 9%. Nail clippings
have been used for permeation studies as well, but they are
not the best model due to the limited nail bed [5] and the available
contact surface with formulation.