What is the distribution coefficient?
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. See also our use the Dalton's Law of Partial Pressures Calculator.
How are LogD values calculated?
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.
What is the difference between LogP and LogD?
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.
How does pH affect distribution coefficient?
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.
How are LogD values used in drug discovery?
LogD values predict drug absorption, distribution, and permeability. Values between 1-3 are typically optimal for oral bioavailability and membrane permeation.
What is a good LogD value for pharmaceuticals?
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. You might also find our Theoretical Yield Calculator useful.