Zwitterions also showed a significant improvement (ca. 30 %), even though these molecules can have multiple ionic partition coefficients (cationic partitions P + , anionic partitions P -, and zwitterionic partitions P z ), which are not considered in the model logDEq. added by considering both acidic and basic pKa into the thermodynamic equilibria. Despite this, the implementation of just one of the two P I app show an improvement in the lipophilic modelling of zwitterions since the pH conditions favored one of these possible ionic species over the others.