AN APPROACH TO ESTIMATE THE AMORPHOUS CONTENT OF PHARMACEUTICAL POWDERS USING CALORIMETRY WITH NO CALIBRATION STANDARDS

Numerous recent articles have focused on methods to determine the amor phous content of pharmaceutical drugs and excipients. While a variety of methods were used, they all share the fact that portions of amorpho us and crystalline materials were blended together and used as calibra tion standards to enable the determination of the amorphous content of the 'unknown' sample. This communication proposes a pragmatic approac h to-estimate the amorphous content of pharmaceutical powders that doe s not require the preparation of blended crystalline/amorphous materia l and uses available calorimetric techniques. This approach has been a dopted in the laboratory to quickly estimate amorphous contents of bul k drug substances and formulated powders for inhalation. (C) 1997 Else vier Science B.V.