Bucco-adhesive tablets containing metoprolol tartarate: formulation, in vitro and in vivo characterization

The main goal of this work was to develop bilayered buccoadhesive tablets to provide delivery of metoprolol tartarate (MT) in a unidirectional fashion to the mucosa. The polymers used included Carbopol 934P, Hydroxy propyl methyl cellulose and Sodium alginate, individually at different concentrations and as a mixture of each two polymers at different ratios. The prepared tablets were characterized by evaluating their physical properties such as weight variation, content uniformity, swelling index, in vitro bioadhesion force and surface pH. The in vitro drug release was also studied. In addition, a comparison of the pharmacological effects of MT on blood pressure and heart rate of healthy rabbits after buccal administration compared to those of oral commercial tablets, Betaloc, was carried out. Moreover, pharmacokinetic parameters of MT were studied. The results revealed that the swelling values increased by increasing the polymer concentration. The adhesion strength was found to be a function of the type and concentration of the polymers used. It was found that tablets containing CP 934P showed the longest residence time and the shortest residence time was obtained with sodium alginate. The rate of drug release was found to be dependent on the type and concentration of polymer used. The reduction effect of MT buccoadhesive tablets on blood pressure and heart rate was found to be faster and greater than that administered orally. The bioavailability of MT after buccal administration was found to be significantly higher than that obtained from an equivalent oral dose.