Design and Optimization of Bilayer Floating Gastroretentive Tablets of Metoprolol

摘要

Objectives: We aimed to formulate and optimize bilayer tablets of metoprolol tartrate consisting of both immediate and sustained release layer. Methods: A 23 factorial design was employed in formulating the GFDDS in which parameters, such as amount of HPMC (X1), sodium bicarbonate + citric acid (X2), and crospovidone (X3) were characterized as independent variables, whereas percent metoprolol release at 30 min (Y1), 4 hr (Y2), 8 hr (Y3), floating lag time (Y4), and total floating time (Y5) were considered as dependent variables. Findings: The formulations showed the biphasic release of metoprolol, where the immediate layer was completely disintegrated within 30 min and the release of the sustained layer was extended to 8 hr. Prompt disintegration of the immediate layer was facilitated by the combined effects of sodium starch glycolate and sodium bicarbonate + citric acid, whereas the extended release was assisted by HPMC. Formulations, where HPMC played the major role, were considered the best formulations. A good correlation was displayed between the experimental and predicted values that confirm the practicability of the model. Application/improvements: This study shows the effect of various variables in the release of metoprolol tartrate and formulates the bilayer tablets of metoprolol tartrate for the immediate and sustained drug release.