| abstract |
Crystalline rosiglitazone maleate of Form A, a process of its preparation by crystallisation from a solvent medium, preparation of rosiglitazone of Form B from Form A and polymorphous mixtures of both Form A and Form B. The forms may be characterised by their X-ray diffraction pattern or infrared absorption spectrum. A process of preparing rosiglitazone free base comprises reduction of 5-[4-[2-(N-methyl-N-(2-pyridyl)amino)ethoxy]benzylidene]thiazolidine-2,4-dione in the presence of a cobalt ion, a ligand and a reducing agent. The cobalt ion is provided as cobaltous chloride, cobaltous diacetate or cobaltic chloride, the ligand is dimethylglyoxime, 2,2'-bipyridyl or 1,10-phenanthroline and the reducing agent is sodium borohydride, lithium borohydride, potassium borohydride, tetraalkylammonium borohydride or zinc borohydride. The free base may be further converted to rosiglitazone maleate. The rosiglitazone free base, rosiglitazone maleate of Form A or rosiglitazone maleate of Form B may be useful in the treatment of various diseases, in particular diabetes mellitus, hyperlipidaemia, hyperglycaemiam, hypertension, cardiovascular disease or eating disorders. |