| abstract |
Disclosed is a novel polymorphic modification "E" of N-cyano-N'-methyl-N '' {2 - [(5-methylimidazol-4-yl) -methylthio] -ethyl} -guanidine (cimetidine " E ") distinguished by its infrared spectroscopic characteristics. According to the process of the invention, cimetidine "E" is produced by providing an aqueous system, which is supersaturated for N-cyano-N'-methyl-N '' - {2 - [(5-methylimidazole-4-il ) -methylthio] -ethyl} -guanidine at a temperature below 30 ° C and contains an organic solvent miscible with water in an amount of at least 40% by volume, crystallizing the solution or emulsion by adding a crystal inoculation, by separating the precipitated crystals, by drying them at a temperature below 20 ° C or by extracting the water content of the crystals with an organic solvent and then drying them. This novel "E" modification of cimetidine exhibits superior rheological and flow characteristics over those of cimetidine "A" and offers several advantages to pharmaceutical techniques. |