Formulation and evaluation of a bioadhesive patch for buccal delivery of tizanidine

Tizanidine hydrochloride (THC1) is an antispasmodic agent which undergoes extensive first pass metabolism making it a possible candidate for buccal delivery. The aim of this study was to prepare a monolayered buccal patch containing THC1 using the emulsification solvent evaporation method. Fourteen formulations were prepared using the polymers Eudragit RS 100 or Eudragit RL 100 and chitosan. Polymer solutions in acetone were combined with a THC1 aqueous solution (in some cases containing chitosan) by homogenization at 9000 rpm for 2 min in the presence of triethyl citrate as plasticizer and cast in novel Teflon molds. Physicochemical properties such as film thickness, in vitro drug release and in vitro mucoadhesion were evaluated after which permeation across sheep buccal mucosa was examined in terms of flux and lag time. Formulations prepared using a Eudragit polymer alone exhibited satisfactory physicomechanical properties but lacked a gradual in vitro drug release pattern. Incorporation of chitosan into formulations resulted in the formation of a porous structure which did exhibit gradual release of drug. In conclusion, THC1 can be delivered by a buccal patch formulated as a blend of Eudragit and chitosan, the latter being necessary to achieve gradual drug release. (C) 2012 Institute of Materia Medica, Chinese Academy of Medical Sciences and Chinese Pharmaceutical Association. Production and hosting by Elsevier B.V. All rights reserved.