Solubility and thermodynamic properties of nimodipine in pure and binary solvents at a series of temperatures

Abstract

The solubilities of nimodipine in pure solvents (i.e., methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, s-butanol, n-pentanol, i-pentanol, acetone, cyclohexanone, acetonitrile, tetrahydrofuran, ethyl formate, methyl acetate, and ethyl acetate) and binary solvent mixtures (methanol + water) was determined using a gravimetric method over a temperature range from 278.15 K to 318.15 K at atmospheric pressure. The solubility data in the single solvents were fitted by the modified Apelblat equation, λh equation, NRTL equation, and Wilson equation, while the solubility data in binary solvent mixtures were correlated by the CNIBS/R-K equation, modified Jouyban-Acree equation, NRTL equation, and Wilson equation. The relative average deviation (RAD), and root mean square deviation (RMSD) were chosen to evaluate the fitting degree of each model. The dissolution enthalpy, entropy, and Gibbs energy changes of nimodipine were evaluated by the Wilson model. The solubility data, thermodynamic parameters and dissolution properties for nimodipine will provide significant guidance for the optimization of the crystallization process in industry.