Long-term stability characterization of a controlled release gastrointestinal therapeutic system coated with a cellulose acetate pseudolatex

The objective of the present study was to study the long term effects of st orage of osmotically controlled gastrointestinal therapeutic system (GITS) in exaggerated conditions of temperature and humidity. Bilayered osmotic ta blets were obtained with atenolol, Polyox(R) N80, Carbopol(R) 934P and magn esium stearate in one layer, and Polyox(R) 303, Carbopol(R) 974, sodium chl oride and magnesium stearate in the other layer. A customized cellulose ace tate (CA) pseudolatex was used to provide semipermeable housing around the tablet and an orifice was drilled into the drug layer to obtain the Atenolo l GITS. The GITS were stored at 4 degreesC (refrigeration), 25 degreesC, 37 degreesC, 45 degreesC, 55 degreesC, 37 degreesC/11% RH, 37 degreesC/51% RH , and 37 degreesC/91% RH. Quantitative X-ray diffraction and dissolution st udies were performed at regular intervals for one year Aqueous CA polymeric film formation continued in GITS stored at higher temperature by gradual e vaporation of moisture and coalescence of polymer. At lower temperatures at enolol crystallinity increased with time, but at higher temperatures the cr ystallinity was decreased. At higher humidity, a decrease in crystallinity was observed. A decrease in dissolution rate and extent was observed at hig her temperature and higher humidity conditions. Exaggerated temperature and humidity conditions affected the dissolution profile by modifying the CA p seudolatex membrane and crystallinity of atenolol.