The second line is logPerm around -8 log units. This area corresponds to the lowest limit of cell-based methods (e.g., CACO-2 or MDCK) as well as PAMPA. With the typical measurement setup for these measurements (donor volume 0.5 mL, permeation area 1.4 cm 2 ), the compound with logPerm = -8 log units will permeate approx. 2% of the permeant in 10 days. The same limit is observable in, e.g. Deur et al. for CACO-2, Chiba et al. for MDCK, or Flaten et al. for PAMPA.