Racemic Ibuprofen Solubility in Ethanol and Aqueous Ethanolic Mixtures

  • Mr Md Rashid, Division of Chemical of Engineering, The University of Queensland, Brisbane, Qld 4072, Australia
  • Prof E White, Division of Chemical of Engineering, The University of Queensland, Brisbane, Qld 4072, Australia
  • A/Prof Howes, Division of Chemical of Engineering, The University of Queensland, Brisbane, Qld 4072, Australia
  • Prof J Litster, School of Chemical Engineering, Purdue University, West Lafayette IN 47907-2100, USA, United States
  • Mr Marziano Ivan, Materials Science, Sandwich Laboratories, Pfizer Limited , Sandwich, Kent CT13 9NJ, United Kingdom, United Kingdom

    • Ibuprofen [2(4-isobutyl-phenyl)-propionic acid] is a very popular analgesic drug. The solubilities of racemic ibuprofen were measured in absolute ethanol and in aqueous-ethanol mixtures (30 to 90% w/w ethanol) in the temperature range 10 to 40ºC. The solubility studies were carried out by dissolution of ibuprofen crystals in stirred Schott bottles in a constant temperature bath. The concentration of ibuprofen was determined by the method of evaporation to dryness .An allowance was made for the small amount of sublimation from dried ibuprofen.
    In absolute ethanol, the solubility increased approximately exponentially with temperatures from 0.593 g of ibuprofen / g ethanol at 10.0oC to 2.144 g/g at 40.0ºC. Results are considered to be accurate to within ± 1% (as 95% confidence). In aqueous-ethanol system at 10ºC, 25ºC, and 40ºC, the solubility (expressed as ibuprofen/ethanol) increased slightly to a maximum level as a small amount of water was added and then decreased with increasing water addition. Phase separation into two immiscible liquid layers saturated with ibuprofen was observed at 40ºC for solvent concentrations between 45 to 65% by weight water in the solvent.