Relationship between the dipole moment and rate of absorption of drugs.

Ten drugs were measured for the rate of buccal absorption and examined for the relationships between the rate constant for absorption and molecular physicochemical parameters. On the ground of the results the molecular dipole moment seems to provide more reliable information on the rate constant of buccal absorption than does the water-lipid partition coefficient or the diffusion constant. Additional perfusion studies on isolated gut were also performed in some cases. A mathematical model was developed for the calculation of the rate constants for those cases in which pH of the system changes linearly with the logarithm of time.