A new process for preparing pure amorphous rosuvastatin calcium, substantially free of impurities, is disclosed. A process comprising hydrolysing a C1 to C5 alkyl ester of rosuvastatin, preferably methyl rosuvastatin or tert-butyl rosuvastatin, with a base, e.g. sodium hydroxide, in the presence of an aprotic solvent, preferably tetrahydrofuran and N,N-dimethyl acetamide, or in the presence of a mixture of an aprotic solvent and water, to obtain a solution of rosuvastatin salt, which may be converted to another rosuvastatin salt using another cation, e.g. with calcium cation to obtain rosuvastatin calcium. Rosuvastatin amine salts may be obtained as well. In another preferred aspect of the invention rosuvastatin free acid may be converted to various rosuvastatin salts, e.g. to rosuvastatin calcium, rosuvastatin sodium or various rosuvastatin amine salts, including rosuvastatin solvates, e.g. rosuvastatin calcium hydrate. Rosuvastatin calcium is useful in the treatment of hyperlipidemia, hypercholesterolemia and atherosclerosis.
