Log D is one of the important parameters used in Lipinski's rule to assess the druggability of a molecule in pharmaceutical formulations. It stands for the logarithm (log 10 ) of the distribution coefficient (D) of a molecule partitioned between an aqueous phase (buffer solution) and a hydrophobic organic solvent phase (e.g. octanol). By definition, distribution coefficient is the ratio of the concentration of the sum of ionized and unionized species of a molecule distributed between the octanol phase and the aqueous buffer phase. Since the pH affects the ionization of a molecule, Log D value which is dependent on the concentrations of the ionized species also varies with pH. In this work, the conventional algebraic method is compared with a more generalized 'dynamic' approach to model the distribution coefficient of monoprotic, diprotic, monoalkaline, amphoteric, diamino-monoprotic and monoprotic acid in the presence of salt, co-solvent. Recently reported experimental log D data of amphoteric molecules such . CC-BY 4.0 International license peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/259770 doi: bioRxiv preprint first posted online Feb. 5, 2018; 2 as Nalidixic acid, Mebendazole, Benazepril and Telmisartan, were analyzed using both these approaches to show their equivalence.
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