title: Solubility of sparingly soluble drug derivatives of anthranilic acid.
abstract: This work is a continuation of our systematic study of the solubility of pharmaceuticals (Pharms). All substances here are derivatives of anthranilic acid, and have an anti-inflammatory direction of action (niflumic acid, flufenamic acid, and diclofenac sodium). The basic thermal properties of pure Pharms, i.e., melting and glass-transition temperatures as well as the enthalpy of melting, have been measured with the differential scanning microcalorimetry technique (DSC). Molar volumes have been calculated with the Barton group contribution method. The equilibrium mole fraction solubilities of three pharmaceuticals were measured in a range of temperatures from 285 to 355 K in three important solvents for Pharm investigations: water, ethanol, and 1-octanol using a dynamic method and spectroscopic UV-vis method. The experimental solubility data have been correlated by means of the commonly known G(E) equation: the NRTL, with the assumption that the systems studied here have revealed simple eutectic mixtures. pK(a) precise measurement values have been investigated with the Bates-Schwarzenbach spectrophotometric method.
authors.affiliation: Faculty of Chemistry, Department of Physical Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland. ula@ch.pw.edu
authors.forename: Urszula
authors.initials: U
authors.lastname: Domańska
authors.forename: Aneta
authors.initials: A
authors.lastname: Pobudkowska
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Pelczarska
mesh_terms: D020003:1-Octanol / Q000737:chemistry; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D004008:Diclofenac / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry; D005439:Flufenamic Acid / Q000737:chemistry; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D015394:Molecular Structure; D009544:Niflumic Acid / Q000737:chemistry; D012995:Solubility; D012997:Solvents / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics; D044366:Transition Temperature; D014867:Water / Q000737:chemistry; D062367:ortho-Aminobenzoates / Q000737:chemistry*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D012997:Solvents; D062367:ortho-Aminobenzoates; D014867:Water; D004008:Diclofenac; D000431:Ethanol; D009544:Niflumic Acid; D005439:Flufenamic Acid; D020003:1-Octanol