2010 Volume 70 Issue 2 Pages 133-140
The objective of this study was to develop oral bilayered film comprising a drug-containing mucoadhesive layer and a drug-free protective layer. The mucoadhesive layer was composed of a mixture of drug and γ-polyglutamic acid (γ-PGA), and the protective layer was composed of a mixture of cellulose acetate (CA) and hypromellose (HPMC). The bilayered film was prepared by laminating the protective layer onto the mucoadhesive layer. This bilayered structure was expected to provide unilateral drug delivery to oral mucosa and to avoid loss of drug due to salivary flow in the oral cavity. Lorazepam (LOR), a mild tranquilizer in the class of drugs known as benzodiazepines and described as effective for patients with psychiatric maladies, was used as a model drug in this study. From the SEM observation of the surface of the protective layer, it appeared that the shape of fine pores and the pore size and distribution were well controlled by altering the mixing ratio of CA and HPMC. The water absorption behavior and the disintegration time were affected by the mixing ratio of CA and HPMC: an increase in the amount of CA increase the amount of water absorbed and an increase in the amount of HPMC shortened the disintegration time. Furthermore, an increase in the amount of HPMC accelerated the release of LOR through the protective layer. These results indicate that the laminating of the protective layer onto the mucoadhesive layer seems to be effective to prevent the loss of LOR caused by salivary flow.
