Abstract:

Crystn. of carbamazepine (CBZ), an antiepileptic drug, pptd. from confined spaces of nonionic microemulsions was investigated. The study was aimed to correlate the structure of the microemulsion [water-in-oil (W/O), bicontinuous, and oil-in-water (O/W)] with the cryst. structure and morphol. of solid CBZ. The pptd. CBZ was studied by DSC, TGA, powder x-ray diffraction, single-crystal x-ray diffraction, SEM, and optical microscopy. The results suggest that the microstructure of the microemulsions influences the crystn. process and allows crystg. polymorphs that exhibit different crystal structure and habits. W/O nanodroplets orient the crystg. CBZ mols. to form a prism-like anhyd. polymorphic form with monoclinic unit cell and P21/n space group. Bicontinuous structures lead to platelike dihydrate crystals with orthorhombic unit cell and Cmca space group. The O/W nanodroplets cause the formation of needlelike dihydrate crystals with monoclinic unit cell and P21/c space group. The morphol. features of solid CBZ remain predetd. by the basic symmetry and parameters of its unit cell. Pptn. of CBZ pseudopolymorphs from supersatd. microemulsion is discussed in terms of oriented attachment that provides perfect packing of numerous sep. nucleated ordered nuclei of CBZ into microscale platelets and then into macroscopic crystals. Crystn. from microemulsion media enabling one to obtain the drug (CBZ) with predicted structure and morphol. should be of great significance for pharmaceutical applications. [on SciFinder(R)]