Bioadhesive film for the transdermal delivery of lidocaine: in vitro and in vivo behavior.

The aim of this work was to study, in vitro and in vivo, the behavior of a skin bioadhesive film containing lidocaine. The film characterization included drug transport studies through skin in vitro and in vivo tape stripping with and without iontophoresis. We studied the effect of drug loading in order to identify the release mechanism. Finally, the release rate was compared with a lidocaine commercial gel, to assess the therapeutic value. From the data obtained it can be concluded that the monolayer film acts as a water-permeable transdermal/dermal patch on application to the skin. The permeation kinetics across the skin was not linear, but the patch acted as a matrix controlling drug delivery. Additionally, the permeation rate increased with drug loading. The in vivo experiments with tape stripping indicated that the presence of water during film application is essential to achieve not only the proper adhesion but also an effective accumulation. The application of electric current to the patch can further increase the amount of drug accumulated in the stratum corneum.