Abstract
The in vitro skin penetration of pharmaceutical or cosmetic ingredients is usually assessed in human or animal tissue. However, there are ethical and practical difficulties associated with sourcing these materials; variability between donors may also be problematic when interpreting experimental data. Hence, there has been much interest in identifying a robust and high throughput model to study skin permeation that would generate more reproducible results. Here we investigate the permeability of a model active, niacinamide (NIA), in (i) conventional vertical Franz diffusion cells with excised human skin or porcine skin and (ii) a recently developed Parallel Artificial Membrane Permeation Assay (PAMPA) model. Both finite and infinite dose conditions were evaluated in both models using a series of simple NIA solutions and one commercial preparation. The Franz diffusion cell studies were run over 24 h while PAMPA experiments were conducted for 2.5 h. A linear correlation between both models was observed for the cumulative amount of NIA permeated in tested models under finite dose conditions. The corresponding correlation coefficients (r²) were 0.88 for porcine skin and 0.71 for human skin. These results confirm the potential of the PAMPA model as a useful screening tool for topical formulations. Future studies will build on these findings and expand further the range of actives investigated.