DESIGN AND EVALUATION OF CHITOSAN ETHYLCELLULOSE MUCOADHESIVE BILAYERED DEVICES FOR BUCCAL DRUG-DELIVERY/

This paper describes the preparation of new buccal bilayered devices c omprising a drug-containing mucoadhesive layer and a drug-free backing layer, by two different methods. Bilaminated films were produced by a casting/solvent evaporation technique and bilayered tablets were obta ined by direct compression. The mucoadhesive layer was composed of a m ixture of drug and chitosan, with or without an anionic crosslinking p olymer (polycarbophil, sodium alginate, gellan gum), and the backing l ayer was made of ethylcellulose. The double-layered structure design w as expected to provide drug delivery in a unidirectional fashion to th e mucosa and avoid loss of drug due to wash-out with saliva. Using nif edipine and propranolol hydrochloride as slightly and highly water-sol uble model drugs, respectively, it was demonstrated that these new dev ices show promising potential for use in controlled delivery of drugs to the oral cavity. The uncrosslinked chitosan-containing devices abso rbed a large quantity of water, gelled and then eroded, allowing drug release. The bilaminated films showed a sustained drug release in a ph osphate buffer (pH 6.4). Furthermore, tablets that displayed controlle d swelling and drug release and adequate adhesivity were produced by i n situ crosslinking the chitosan with polycarbophil. (C) 1998 Elsevier Science B.V. All rights reserved.