PROCEDURE FOR PREPARATION OF AMORPHOUS AND CRYSTAL FORMS OF CANDESARTAN CILEXETIL

摘要

The submitted invention assures improved procedures for preparation of crystal and amorphous forms of candesartan cilexetil. In the first embodiment, candesartan cilexetil, e.g. from the reaction mixture after the finished synthesis of candesartan cilexetil, is purified with column chromatography by using normal or reversed chromatographic conditions. Fractions containing candesartan cilexetil are combined and liophylized (freeze dried) to obtain pure amorphous candesartan cilexetil which may be optionally transformed into forms I and/or II either by crystallisation, precipitation or suspension. In one of the embodiments, amorphous candesartan cilexetil is thermally transformed into form II by heating the suspension of amorphous candesartan cilexetil in an inert solvent or solvent system.