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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.
Examples for log P and log D calculations. The following examples show logP/logD results for special molecules types. The calculations were performed with the default settings of the logP plugin.
log D is the logarithm of the distribution coefficient. Definition of log P and log D. The partition coefficient is the ratio of the concentration of the compound in octanol to its concentration in water.
Lipophilicity is represented by the descriptors logP (also known as Kow or Pow) and logD, and is used, for example, to help predict in-vivo permeability of active compounds in drug discovery; to anticipate the impact of insecticides, herbicides, and fertilizers on various species in agrochemicals research; to develop environmental profiles of wa...
Here is a LogD cheat sheet created from their work, summarizing how much affinity is expected from a change based on lipophilicity considerations alone. For a methyl group for example, the median LogD change is about 0.3, indicating that you'd expect about a 2-fold increase in lipophilic potency due to the methyl group's contribution to LogD.
Example 3. Ibuprofen has the typical log D -pH profile that is characteristic of acidic compounds. Lipophilic behavior of ibuprofen will be dominant when its carboxylic group is unionized, which occurs at lower pH.
