RISEDRONATE SODIUM HAVING A VERY LOW CONTENT OF IRON

摘要

The present invention relates to a method of making risedronate sodium substantially free of iron including the steps of refluxing, especially with mechanical agitation, a combination of risedronic acid, a sodium base, especially sodium hydroxide, and an iron-reducing amount of EDTA in a liquid that is water, a lower alkanol, or, especially, a mixture of a lower alkanol and water; and isolating risedronate sodium substantially free of iron from the combination.