Correlation between human skin and Strat-M membrane across diffusion rates that vary over four orders of magnitude. Transdermal diffusion testing was performed for several formulation types commonly used for transdermal delivery. Six Franz cells were used for each formulation-three with Strat-M membrane and three with human cadaver skin. The donor chambers were loaded with 500 µL of the formulations. Samples were collected hourly and analyzed with HPLC.