Figure 6.
Property space for passive permeability constrained by polarity, solubility, and molecular volume. The black line represents the lipophilicity required (logKmem) to achieve a permeability of 1 × 10−6 cm/sec for a given volume. The required lipophilicity to overcome the molecular size penalty we observe places an operational limit on molecular volume ~1500 Å3 (~MW 1200).