Investigating the Effects of Humidity and Temperature on Rate and Kinetics of Theophylline Release from Hydrophilic Matrices

Background and The dissolution of a drug has a major role on its bioavailability. Any change in physico-chemical properties can result in changes in drug release, and furthermore in its bioavailability. Evidence suggest that physicochemical properties of medicinal solids depend on the presence of heat and humidity. In order to overcome such changes, it is necessary to determine the storage conditions required for obtaining a desired drug release.
Theophylline tablets were prepared by Direct Compression method using Carbapol 934 and HPMC K15M. After conducting some initial tests, the tablets were subjected to different conditions of temperature and humidity for six months. Theophylline release from different formulations was analyzed. The data were then fitted to Kinetic model. Differential Scanning Calorimetry (DSC) was used to determine the physical stability of tablets and possible adverse interactions between drugs with polymers or other materials.
The results of drug release from different formulations showed no significant differences between various times (zero, three, and six months) (P= 0.207). Also, by studying the Dsc thermogram of different formulations the peak Theophylline was seen at approximately 275°C, and the thermogram did not show any changes.
In this study, keeping Theophylline tablets for three and six months in different conditions did not cause significant changes in drug release. Moreover, no change was observed in the physical stability of tablets.