NEW CRYSTAL FORMS OF OXCARBAZEPINE AND PROCESSES FOR THEIR PREPARATION

摘要

The present invention provides for new crystal forms of oxcarbazepine, more particularly oxcarbazepine Forms B, C, D and E. The present invention further provides processes for preparation of these forms. Form B is prepared by evaporating the solvents from a solution of oxcarbazepine in toluene and dichloromethane. Form B is also obtained by immediately cooling the solution of oxcarbazepine and toluene. Cooling the same solution at a slower rate, but still fairly rapidly, results in oxcarbazepine Form C. Cooling th same solution at even a slower rate results in another Form, oxcarbazepine Form D. Oxcarbazepine Form E, a solvate of chloroform, is obtained by precipitating a solution of oxcarbazepine and chloroform. The present invention also provides processes for converting one of the newly discovered crystal forms of oxcarbazepine into another crystal form, including Form A, which is in the prior art. These conversions may occur by storage at ambient temperature, by heating one particular Form or treatment with a protic solvent.