Solubility and apparent specific volume at saturation of some pharmaceutical salts in methanol plus water mixtures at 298.15 K

Abstract

Equilibrium solubility of sodium naproxen (Na.NAP), procaine hydrochloride (PC.HCl), and lysine clonixinate (Lys.Clon), was determined in methanol + water mixtures at 298.15 K. Mole fraction solubility of Na.NAP increases from neat water (x(3) = 1.71 x 10(-2)) to reach a maximum in the mixture with w(1) = 0.90 (x(3) = 5.05 x 10(-2)); the solubility of PC.HCI increases from neat water (x(3) = 9.68 x 10(-2)) to reach a maximum in the mixture with w(1) = 0.20 (x(3) = 0.1032); whereas, the solubility of Lys.Clon increases from neat water (x(3) = 3.54 x 10(-2)) to reach a maximum in the mixture with w(1) = 0.60 (x(3) = 6.33 x 10(-2)). The generated solubility data are mathematically represented by using the Jouyban-Acree model with very good error level (average of 1.2% for molar solubilities). In addition, the apparent specific volumes at saturation of these drugs were also calculated in all the mixtures under study using the measured densities of the saturated solutions. In this way, the average apparent volumes at saturation in these mixtures could be considered as follows: 0.699 cm(3) g(-1) for Na.NAP, 0.821 cm(3) g(-1) for PC-HCl, and 0.730 cm(3) g(-1) for Lys.Clon. (C) 2016 Elsevier B.V. All rights reserved.