Solution thermodynamics and preferential solvation of meloxicam in propylene glycol +water mixtures

Andrés R. Holguín, Daniel R. Delgado, Fleming Martínez*, Yizhak Marcus

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

128 Scopus citations

Abstract

The equilibrium solubilities of the analgesic drug meloxicam (MEL) in propylene glycol + water mixtures were determined at several temperatures from 293.15 to 313.15 K. The Gibbs energy, enthalpy, and entropy of solution and of mixing were obtained from these solubility data. The solubility was maximal in neat propylene glycol and very low in pure water at all temperatures studied. A nonlinear plot of Δ solnH° versus Δ solnG° gave a negative slope from pure water up to 0.80 mass fraction of propylene glycol and a positive slope above this composition up to neat propylene glycol, at the mean temperature 303.15 K. Accordingly, the driving mechanism for MEL solubility in the water-rich mixtures was the entropy, probably due to water-structure loss around nonpolar moieties of the drug, while for the propylene glycol-rich mixtures it was the enthalpy, probably due to better solvation of the drug. The preferential solvation of MEL by the components of the solvent was estimated by means of the inverse Kirkwood-Buff integral method, showing rather small preferential solvation of MEL by propylene glycol at all compositions.

Original languageEnglish
Pages (from-to)1987-1999
Number of pages13
JournalJournal of Solution Chemistry
Volume40
Issue number12
DOIs
StatePublished - Dec 2011

Keywords

  • Activity coefficients
  • Meloxicam
  • Preferential solvation
  • Propylene glycol solubility
  • Solution thermodynamics

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