Development and Evaluation of Gastroretentive Atenolol Tablets

The low oral bioavailability of atenolol is primarily because of its poor absorption from the lower gastrointestinal tract. Gastroretentive dosage forms provide an opportunity to deliver the drug with absorption window in the proximal part of the GIT thereby increasing their bioavailability. The objective of this study was to develop a dosage form for atenolol with the objective of increasing the gastric residence and there by its oral bioavailability. Different formulations of floating tablets of atenolol (AT1-AT10) were prepared by varying the composition of hydroxypropyl methyl cellulose (HPMC) K100, lactose and citric acid. The tablets were evaluated for various parameters like friability, weight variation, content variation, floating lag time, total buoyancy and in vitro dissolution. The physicochemical properties of the prepared formulations were found to possess adequate physical integrity. Formulation AT8 showed the lowest floating lag time with 14 h buoyancy. Drug release was found to be dependent on the concentration of HPMC K100 and lactose in the formulation. Further, the increase in amount of citric acid leads to increase in atenolol release rate while reduces the floating time. The findings revealed that the formulation AT8 retarded the atenolol release (~73% in 12 h) and followed zero order kinetics. The in vitro data observed here substantiate the potential of the prepared formulation to provide adequate drug release and buoyancy to improve the bioavailability of atenolol, which necessitate further in vivo studies.