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The distribution coefficient, log D, is the ratio of the sum of the concentrations of all forms of the compound (ionized plus un-ionized) in each of the two phases, one essentially always aqueous; as such, it depends on the pH of the aqueous phase, and log D = log P for non-ionizable compounds at any pH.
This background material explains the theory behind the log P and log D calculation: Introduction. Symbols used. Definition of logP and logD. Example. Partition and distribution coefficients. Relation between macro and micro partition coefficients. LogP calculation methods. Examples for logP and logD calculations.
6 sty 2024 · LogD = LogP − log (1 + 10 (pH − pKa) δ i) where δ i = {1, − 1} for acids and bases, respectively. The astute reader will notice that only a single pKa is provided here which is the global pKa. In Figure 4 I show how the LogD varies with pH for two acidic and two basic drugs.
12 sty 2019 · Of particular interest is the log D at pH = 7.4 (the physiological pH of blood serum). Applications like Marvin allow the user to calculate the logD but also display the pH distribution profile, as shown below for Warfarin.
In order to accurately measure and report lipophilicity, the scientist must take great care in measurement of logP at a pH where the compound exists in its neutral form (>pH 12 in the case of 5-Methoxy-2-(1-piperidin-4-ylpropyl)pyridine), and/or report logD at a specific pH.
LogP and logD calculations - Documentation. This background material explains the theory behind the log P and log D calculation: Introduction. Symbols used. Definition of logP and logD. Example. Partition and distribution coefficients. Relation between macro and micro partition coefficients. LogP calculation methods.
The trainable logP calculation (available from version 5.1.3) offers the user to define his own logP database and calculate logP values based on experimental data. New fragment value extensions make a more precise calculation possible.
