Transdermal films containing tizanidine: in vitro and in vivo evaluation

Myogenic pain and spasticity are of most important symptoms that occupy clinician's thinking in order to relief of discomfort associated with acute, painful disorders of skeletal muscles. Oral tizanidine hydrochloride (THCl) suffers from extensive hepatic first pass effect and hence low bioavailability. The purpose of the present study was to develop bioadhesive transdermal delivery systems of THCl using some of Eudragit polymers and chitosan in order to optimize its release profile, and the overall clinical performance. The prepared formulae were subjected to physicochemical examination, in vitro release, in vitro skin permeation studies, stability studies and in vivo studies. It was observed that Higuchi diffusion model was the best fitted model for the release of the drug from the tested films. The results obtained were promising, with (Eudragit NE 30D: Eudragit R 100, ENE: ERL (2:1)) film showing the most satisfactory combined physicochemical, in vitro, stability and in vivo studies.