Figure 1.

Principal components analysis (PCA) of an oral drug reference data set⁸ (gray squares; n = 529) and the data set of 225 compounds investigated for OATP inhibition (black squares; n = 225) (a). The circle indicates the 95% confidence interval of the PCA for the oral drug reference data set. The first principal component (x-axis) is governed by polarity and hydrogen bonding, which increases to the right, whereas the second principal component (y-axis) is governed by lipophilicity, which increases upward. Distribution of molecular charge at pH 7.4 of the 225 compounds investigated for OATP inhibition (b).