Long-term stability characterization of a controlled release gastrointestinal therapeutic system coated with a...

The objective of the present study was to study the long term effects of storage of osmotically controlled gastrointestinal therapeutic system (GITS) in exaggerated conditions of temperature and humidity. Bilayered osmotic tablets were obtained with atenolol, Polyox N80, Carbopol 934P and magnesium stearate in one layer, and Polyox 303, Carbopol 974, sodium chloride and magnesium stearate in the other layer. A customized cellulose acetate (CA) pseudolatex was used to provide semipermeable housing around the tablet and an orifice was drilled into the drug layer to obtain the Atenolol GITS. The GITS were stored at 4 degrees C (refrigeration), 25 degrees C, 37 degrees C, 45 degrees C, 55 degrees C, 37 degrees C/11% RH, 37 degrees C/51% RH, and 37 degrees C/91% RH. Quantitative X-ray diffraction and dissolution studies were performed at regular intervals for one year. Aqueous CA polymeric film formation continued in GITS stored at higher temperature by gradual evaporation of moisture and coalescence of polymer. At lower temperatures atenolol crystallinity increased with time, but at higher temperatures the crystallinity was decreased. At higher humidity, a decrease in crystallinity was observed. A decrease in dissolution rate and extent was observed at higher temperature and higher humidity conditions. Exaggerated temperature and humidity conditions affected the dissolution profile by modifying the CA pseudolatex membrane and crystallinity of atenolol.