Log S

LogS is directly related to the water solubility of a drug and it is defined as a common solubility unit corresponding to the 10-based logarithm of the solubility of a molecule measured in mol/L. The solubility and logS of a drug can be divided in:

  • Intrinsic solubility (log S 0) - solubility measured after equilibrium between the dissolved and solid state at a pH where the compound is neutral
  • pH-dependent solubility - the solvation equilibrium is affected by the solution pH.1

In DrugBank, it is possible to find the experimental and predicted value of logS. 


  1. ChemAxon [Link]