Effect of storage on theophylline release from commercially available sustained-release products

ABSTRACT

Four commercially available sustained- release theophylline products were evaluated with regard to their release rate profile using the USP basket method. The dissoluation medium was phosphate buffer [pH7.5]. a wide variation in the drug release was shown and was attributed to differences in the additives and the method of manufacturing of these products. these brands were stored at 40°C/80% relative humidity [R.H.] and their in-vitro dissolution as well as their theophylline content ere followed for upto twenty months under these storage condition. While no alterationof theophylline content was shown upon storage, changes in drug release patterns were observed in three of these products. dramatic changes in both the T50% and T80% were also found. These results reveal the possibility of a change in the bioavailability of these products upon storage