Process for Preparing Pure Amorphous Rosuvastatin Calcuim

A process for producing amorphous rosuvastatin calcium, which includes the steps of:

• a) hydrolyzing a C1 to C5 alkyl ester of rosuvastatin with a base in an aprotic solvent;
• b) removing the aprotic solvent to obtain a residue;
• c) combining the residue with water to obtain an aqueous solution of rosuvastatin salt of a base;
• d) optionally washing the obtained aqueous solution with a water immiscible organic solvent;
• e) optionally removing the organic solvent;
• f) adding a source of calcium to the resulted solution to precipitate rosuvastatin calcium;
• and
• g) isolating the amorphous rosuvastatin calcium salt.

A process for producing rosuvastatin free acid, which includes the steps of:

• a) hydrolysing a C1 to C5 alkyl ester of rosuvastatin with a base in an aprotic solvent,
• b) removing excess of organic aprotic solvent;
• c) optionally diluting water poor solution with additional water,
• d) optionally washing thus obtained aqueous solution of rosuvastatin salt of a base with a water immiscible organic solvent
• e) acidifying aqueous solution of rosuvastatin salt of a base,
• f) extracting the resulted rosuvastatin acid with the water immiscible organic solvent,
• g) removing the water immiscible organic solvent from the resulted extract to obtain isolated rosuvastatin free acid.