Effect of packaging and storage on the stability of carbamazepine tablets

The effect of packaging and storage on carbamazepine (CBZ) tablets was examined using Tegretol and Tegral, dispensed in strip seals, and Finlepsin, dispensed in bottles. Tegretol and Tegral tablets were stored in their original strips at 40 degrees C, 50 degrees C, and 60 degrees C for 6 months, 3 months, and 1 month, respectively, at 75% relative humidity (RH). Also, tablets were removed from their strips, placed in bottles, and exposed daily to 97% RH at 40 degrees C for 5 min for 30 days. Finlepsin tablets were exposed to 97% RH at 25 degrees C or 40 degrees C for 1 month by removing bottle caps daily for 5 min. Dissolution was used to assess in vitro tablet performance, and high-performance liquid chromatography (HPLC) was used to evaluate the chemical stability of CBZ. Results show that Tegretol tablets were not affected by the tested stress conditions. Tegral tablets, stored in their strips at 50 degrees C or 60 degrees C and 75% RH, showed increased disintegration and dissolution. The effect of 40 degrees C/75% RH for 6 months was similar to 1-month storage at 40 degrees C/97% RH; the tablets hardened and dissolved less than fresh Tegral tablets. Removal of Tegral tablets from their original strips resulted in only 7% dissolved in 60 min. For Finlepsin, the effect of 97% RH at 40 degrees C was more profound than 97% RH at 25 degrees C, but both conditions caused a decrease in dissolution, the extent of which was dependent on tablet position in the bottle. Stressed CBZ tablets, however, showed no change in the chemical stability of CBZ under all tested conditions.