Product

A process of purifying citalopram, either in racemic or enantiomeric form, which process comprises:

• (i) providing a crude mixture comprising citalopram, either in racemic or enantiomeric form, dissolved in a water immiscible organic solvent, and which mixture also includes one or more citalopram derivatives which are present as citalopram impurities;
• (ii) washing said crude mixture with at least one dilute aqueous solution of a polybasic acid, either in free form or as a partial alkali metal salt, so as to remove citalopram impurities from the crude mixture;
• (iii) washing the residual crude mixture obtained further to step (ii) with at least one further dilute aqueous solution of a polybasic acid, either in free form or as a partial alkali metal salt, so as to separate said citalopram from impurities remaining in said residual crude mixture, by extraction of citalopram, as a salt formed with the polybasic acid, into an aqueous phase and optionally washing the resulting aqueous phase with an organic solvent;
• (iv) adding a base to the aqueous phase in an amount sufficient to liberate citalopram free base and extracting the liberated citalopram into an organic solvent,
• (v) optionally re-extracting citalopram free base from the organic extract obtained further to step (iv) by washing with at least one further dilute aqueous solution of a polybasic acid, either in free form or as a partial alkali metal salt, so as to extract citalopram, as a salt formed with the polybasic acid, into an aqueous phase and adding thereto a base in an amount sufficient to liberate citalopram free base and further extracting the liberated citalopram into an organic solvent;
• and
• (vi) where required converting the free base obtained further to step (iv) or (v) to a pharmaceutically acceptable salt thereof