• Tetracycline;
  • Docusate;
  • Ionic Liquids;
  • Synthesis;
  • Drug-like properties;
  • Solubility;
  • Partition Coefficient;
  • Liposomes;
  • UV-VIS spectroscopy


Recently, efforts have been put on the development of new drug formulations using ionic liquid framework. In this work, two different species of abroad-spectrum polyketide antibiotic, tetracycline, are studied in terms of some important properties for antibiotics such as solubility in water and hydrophilic–hydrophobic balance. Tetracycline was used as cation, whereas docusate, a biocompatible anion, which enables the tailoring of the hydrophilicity of salts, was chosen as the anion. The developed innovative ion pair, tetracycline docusate, was characterized in terms of its thermal stability, water solubility, octanol–water, and liposome–water partition coefficients, using UV–vis spectrophotometry because of the absorbance of tetracycline around 270 nm. Egg yolk phosphatidylcholine liposomes were used as cell membrane models, and the interactions of both tetracycline hydrochloride and tetracycline docusate with the liposomes were quantified by determination of the partition coefficient using derivative spectrophotometry. A theoretical model based on simple partition drugs between two different media was used to determine the partition coefficient in liposomes. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:1504–1512, 2013