The Dissolution Behavior and Solvent Effect Analysis of Pramipexole in Pure Organic Solvents

The dissolution behavior of pramipexole in organic solvents was studied, and the solubility results were correlated by using different equations. Over the temperature range from 273.15 to 313.15 K, the largest data in mole fraction were in methanol (9.855 × 10^–2 at 313.15 K) followed by dimethyl sulfoxide (DMSO, 8.914 × 10^–2 at 313.15 K), N,N-dimethylformamide (DMF, 8.596 × 10^–2 at 313.15 K), ethanol (7.494 × 10^–2 at 313.15 K), n-propanol (5.103 × 10^–2 at 313.15 K), 1,4-dioxane (4.418 × 10^–2 at 313.15 K), 2-propanol (3.372 × 10^–2 at 313.15 K), ethyl acetate (1.680 × 10^–2 at 313.15 K), acetonitrile (7.096 × 10^–3 at 313.15 K), toluene (5.566 × 10^–3 at 313.15 K), 2-butanone (2.172 × 10^–3 at 313.15 K), and cyclohexane (1.758 × 10^–4 at 313.15 K). To study the influence of solute–solvent intermolecular interactions on the solubility in pure solvents, a multiple linear regression analysis (MLRA) including the hydrogen bond acidity, hydrogen bond basicity, dipolarity/polarizability, and Hildebrand solubility parameter of the solvent was performed. The results indicate that the dissolution process of pramipexole was mainly influenced by the hydrogen bond acidity, hydrogen bond basicity, and dipolarity/polarizability of the solvent. Studying the dissolution behavior of pramipexole in organic solvents is important to its application.