Study of the release rate of compound Metoprolol and Amlodipine Bilayer Tablets in vitro

Objective To establish determination method for release rate of Tartaric acid Metoprolol in the slow-release layer and Amlodipine bilayer in the quick-release layer of Metoprolol and Besylate Amlodipine bilayer Tablets.Methods The different dissolution methods,dissolution mediums and rotating speeds which effected the release of sustained release layer were studied on.The release of the bilayer tablets were determined by HPLC.Results Release of the quick-release layer was up to more than 90% within 45 min,the release of the slow-release layer was up to more than 90% within 12 h which met the requirements of the zero level dynamics equation.Conclusion The method which established for in vitro dissolution rate determination is exact.