The pressure-temperature phase diagram of the dimorphism of racemic m-nisoldipine is constructed using temperatures and enthalpies of fusion of forms A and B. At ordinary pressure, the transition from form B to form A is found to occur around 192K, which indicates that these polymorphs are enantiotropically related and that form A is stable at room temperature. Nevertheless, the phase relationship turns to be monotropic when pressures become greater than about 100MPa, which indicates that form B becomes the sole stable phase.
Keywords: Crystalline polymorphism; Diagramme P–T topologique; M-nisoldipine racémique; Polymorphisme cristallin; Racemic m-nisoldipine; Stabilité thermodynamique; Thermodynamic stability; Topological P–T diagram.
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