Enter your Concentration in Organic Phase, Concentration in Aqueous Phase, pH Value, and Temperature, then select your Calculation Type to find the Distribution Coefficient — along with the Log Value and Partition Ratio — showing exactly how a solute distributes itself between two liquid phases.
Distribution Coefficient
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Log Value
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Partition Ratio
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The distribution coefficient (LogD) is the ratio of concentrations of a compound between two phases at equilibrium, typically octanol-water, and accounts for all species of the compound at a given pH.
LogD is calculated as the logarithm (base 10) of the ratio of total concentration in the organic phase to total concentration in the aqueous phase at a specific pH.
LogP is the partition coefficient of the neutral form only, while LogD is the distribution coefficient that accounts for all ionized and neutral species at a given pH.
pH significantly affects LogD for ionizable compounds. As pH changes, the ionization state changes, which affects the compound's affinity for aqueous versus organic phases.
LogD values predict drug absorption, distribution, and permeability. Values between 1-3 are typically optimal for oral bioavailability and membrane permeation.
For oral drugs, LogD values between 1-3 are generally preferred. Values below 0 may indicate poor membrane permeability, while values above 5 may cause poor solubility.