EFFECT OF CRYOGRINDING ON PHYSICOCHEMICAL PROPERTIES OF DRUGS .2. CORTISONE-ACETATE - PARTICLES SIZES AND POLYMORPHIC TRANSITION

The low temperature grinding (at 78 K) of cortisone acetate was carrie d out. From electron microscopy data, there were determined a form, me an linear sizes of particles and then specific surface was calculated. From X-ray data, a part of microcrystalline fraction in cryogrinded s amples was calculated. As was indicated by X-ray data, the mechano-ind uced phase transition from ''monoclinic'' phase (form F-I) to ''orthor hombic'' one (form F-II) takes place as a result of 10-min grinding. T he transition is confirmed by IR-spectroscopy results too. The local p ressures induced by the mechanical stress seems to be the main cause o f the phase transition observed.