Study of accelerated storage conditions affecting physical characteristics, in-vitro dissolution and stability of bioadhesive containing tablets.

The effect of storage at different temperatures and relative humidities on directly compressed tablets of indometacin containing 20% polycarbophil was studied for up to 16 weeks. The prepared tablets were stored in closed containers of type III glass under different conditions of temperature (30 degrees C, 40 degrees C and 50 degrees C), in open petri dishes at room temperature, at relative humidity (RH) (31%, 79.3% and 98%), and combinations of temperature and relative humidity (30 degrees C/92.9% RH, 40 degrees C/79.5% RH and 50 degrees C/65% RH). The tablet properties such as mean weight, hardness, disintegration, in-vitro dissolution and drug content were monitored just after preparation and after 2, 4, 8, 12 and 16 weeks of storage. The tablets mean weight was significantly (p < 0.05) increased at RH 98% and at 30 degrees C/92.9% RH and non-significantly increased at 79.3% RH, 40 degrees C/79.5% RH and 50 degrees C/65% RH. There was no effect of temperature on mean weight. The hardness of the tablets increased slightly at 31% RH and decreased at 79.3% RH and at 40 degrees C/79.5% RH and became zero at 98% RH and at 30 degrees C/92.9% RH. The increase in temperature caused slight increase in tablets hardness. Tablets stored at 98% RH and at 30 degrees C/92% RH showed an increase in disintegration time associated with a decrease in rate of dissolution and indometacin content. No effect on drug content or dissolution profile was observed as a result of storage under other conditions. These findings point out to the importance of proper protection of indometacin tablets containing polycarbophil from high temperature and humidity conditions in order to ensure stability of the drug.