Optimization of Unidirectional Mucoadhesive Buccal Patches Based on Chitosan and Pluronic® F-127 for Metoprolol Controlled Release: In Vitro and Ex Vivo Evaluations

Purpose The aim of this work was to optimize unidirectional buccal patches loaded with metoprolol (MT-MBPs) to provide adequate mucoadhesive and water uptake properties as well as controlled drug release for the effective treatment of different cardiovascular diseases. Methods The patches were prepared layer-by-layer using the solvent casting method. A central composite design was employed to statistically optimize the formulation variables. Chitosan and Pluronic® F-127 (poloxamer 407) concentrations were chosen as the independent variables, while ex vivo mucoadhesive force, ex vivo residence time, in vitro water uptake (%), and in vitro drug release (%) were to be considered the dependent variables. The optimized formulation was also characterized and evaluated in terms of morphology, thermal behavior, tensile strength, elongation at break, and ex vivo drug permeation. Results The optimized MT-MBPs were successful in terms of mucoadhesive force (3.58 ± 0.62 N), residence time (342.67 ± 17.21 min), and water uptake at 1 h (24.53 ± 3.62%). A controlled drug release was obtained for 8 h. Thermal and morphologic analyses demonstrated that metoprolol was homogeneously distributed throughout the microporous chitosan-based polymer matrix. Furthermore, the MT-MBPs exhibited a tensile strength of 3.76 ± 0.55 N/mm 2 and an elongation at break of 36.52 ± 13.88%. The results of ex vivo permeation through pig buccal mucosa indicated that therapeutic metoprolol concentrations can be reached by using a patch of 5.62 cm 2 . Conclusions Optimal composition of the MT-MBPs included 2.9% (w/v) and 2.6% (w/v) of chitosan and Pluronic® F-127, respectively, which constitutes the most suitable makeup for metoprolol buccal delivery. Graphical Abstract