[Change in the drug release behavior of theophylline sustained-release tablets after division into two halves]

Dividing a tablet into two halves and providing them to patients is a routine approach in clinical practice. Obviously, the drug release behavior of tablets should be constant, regardless of the dividing process. Here, we investigated the change in drug release behavior after dividing tablets into two halves. Five commercial theophylline sustained-release tablets designed to be taken once a day were used as test tablets (two original products and three generic products). A 24 h dissolution test was performed for each tablet, and changes in drug release behavior were evaluated using similarity factors, f2, calculated from the drug release profiles. The drug release rates were substantially increased by dividing the tablets into two halves. Analysis of variance (ANOVA) revealed that the effect of the dividing process on drug release behavior was more significant than that of changing the products. We further observed the feature of cross sectioning of the surface of the tablets using a scanning electron microscope (SEM) and a laser-scanning microscope (LSM). The microscopic observations confirmed that the surface became rough and developed many cavities with the prolongation of the duration of the dissolution test. This study clarified that the division of tablets into two halves exerts significant effects on their drug release behavior, and may offer a profound insight into the proper use of pharmaceutical products.