Permeability prediction for zwitterions via chromatographic indexes and classification into 'certain' and 'uncertain'.

The development of zwitterions to a drug is likely to be more challenging than compounds of other charge types. Two chromatographic indexes (log k'80 PLRP-S and log K) can be successfully used as permeability classifiers of ampholytes. Moreover, a pragmatic classification into ordinary ampholytes; zwitterions 'certain' (i.