Effect of gastric residence time on the oral absorption of rebamipide sustained-release tablets in beagle dogs

Purpose Rebamipide (RBM) is known to have a specific absorption window in the upper GI tract. However, there have been no in vivo studies reporting the regional absorption of RBM, which may lead to misjudgment in formulation development considering the many other physiological factors involved in oral absorption. Therefore, this study aimed to assess the regional absorption of RBM. Methods Barium sulfate was incorporated into RBM-sustained release (SR) tablets as a radiopaque marker and the location of RBM-SR tablets was monitored using X-ray imaging after oral administration of RBM-SR tablets in Beagle dogs. Results Based on the gastric residence time (GRT) of RBM-SR tablets, dogs were divided into two groups: GRT(low) for 0.25 and 1.5 h and GRT(high) for 3 and 5 h. GRT(high) had significantly delayed time to reach peak plasma concentration (T-max), longer mean residence time (MRT), and higher area under the plasma concentration-time curve from time zero to the last observation time point (AUC(last)) than GRT(low), which indicates the presence of an absorption window in the upper GI tract. Conclusion This study, for the first time, reports on the regional absorption of RBM. The findings of this study may be useful for developing RBM-SR formulations.