Studies on the polymorphism of barbital.

Crystalline samples of barbital obtained by isothermal crystallization from various solvents or by sublimation were analysed. Morphological, thermomicroscopical, thermal, IR, density and initial dissolution rate studies were carried out. X-ray analysis according to Debye-Scherrer was realised after 9-month storage of samples at room conditions. The ability of barbital to form polymorphic modifications was confirmed but the conclusions of previous works were discussed. It was found that the stability of metastable crystal structures II, III and IV was high enough to make them commercially feasible.