Estimation of the ethanol/water solubility profile from the octanol/water partition coefficient

Stephen G. MacHatha, Samuel H. Yalkowsky

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


While the ethanol/water solubility profiles of very polar and very non-polar drugs are monotonic, many semi-polar drugs show a maximum solubility at an ethanol volume fraction (f max) between 0 and 1. A sigmoidal relationship was observed between the value of f max and the log of the octanol/water partition coefficient (log K ow) of the solute. This relationship reasonably predicts the value of the volume fraction of ethanol that gives maximum solubility (f max). Combining this sigmoidal relationship with the previously reported linear relationship between the log K ow and the initial slope of the plot of log solubility versus ethanol composition [Li, A., Yalkowsky, S.H., 1994. Solubility of organic solutes in ethanol/water mixtures. J. Pharm. Sci. 83, 1735-1740] enables the estimation of the total ethanol/water solubility profile.

Original languageEnglish (US)
Pages (from-to)111-115
Number of pages5
JournalInternational Journal of Pharmaceutics
Issue number1-2
StatePublished - Nov 22 2004


  • Ethanol/water solubility profile
  • Log-linear
  • Prediction of maximum solubility
  • Sigmoidal

ASJC Scopus subject areas

  • Pharmaceutical Science


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