Stability characterization of controlled release coprecipitates and solid dispersions

The present study was conducted to determine the effects of ageing at exagg erated storage conditions;on controlled release tablets prepared with indom ethacin-Eudragit (R) coprecipitates (CPs) and solid dispersions (SDs). CPs and SDs compressed as tablets were stored at -20, 4, 37, 45, 55, 37 degrees C/11% RH, 37 degrees C/51% RH and 37 degrees C/91% RH. The samples were an alyzed over a period of six months for their dissolution, crystalline rever sion and thermal changes. Samples stored at extremely low temperatures, hig her temperatures and humidity conditions exhibited a significant decrease i n dissolution rates. However, no significant change in the release rates wa s observed for samples stored at 4 degrees C. The degree of crystallinity i ncreased over a period of time as confirmed by X-ray diffractometry, DSC da ta demonstrated that indomethacin exists in two polymorphic forms, Form I ( mp 160-161 degrees C) and Form II (mp 153-154 degrees C). CPs showed an end otherm of Form I, whereas SDs showed a mixture of Form I and II. (C) 2000 E lsevier Science B.V. All rights reserved.