NOVEL PROCESS FOR THE PREPARATION OF BISPHOSPHONIC ACIDS

摘要

The present invention relates to a process for the preparation of bisphosphonic acids and salts thereof, in particular monosodium salts thereof. The invention also relates to the conversion of the bisphosphonic acids to their sodium salts using an aqueous-organic solvent system. The present invention further relates to the conversion of variable hydrate forms of risedronic acid monosodium salt into a pharmaceutically acceptable hemipentahydrate form by crystallization using an aqueous-organic solvent system.