a Transungual permeation of CPO through the three sizes of human toenails. b Concentration of CPO in the area of application (a) and subsequent peripheral nail sections (b, c, d) in each of the three sizes of the nails after the transungual permeation study. c Correlation between the log concentrations of CPO and MR in the nail sections (a, b, c, d) after transungual permeation study