Free interstitial drug as a function of the initial load of soluble drug, ci0 and the intracellular binding capacity, bc,max. Free interstitial drug as a function of the initial load of soluble drug, ci0 and the intracellular binding capacity, bc,max. A, bc,max = 60 μmol/L; B, bc,max = 120 μmol/L. Solid line, spatially averaged numerical solution of Eqs. F-L1 using the variable values listed in Table 1, except for bc,max; Dashes, the same as solid line, except for α → ∞. Color scheme: ci0 = 100 μmol/L (gray), ci0 = 200 μmol/L (black), and ci0 = 250 μmol/L (light gray). Abraham Rami Tzafriri et al. Clin Cancer Res 2005;11:826-834 ©2005 by American Association for Cancer Research