Physicochemical characterization and evaluation of buccal adhesive tabletscontaining omeprazole

The objective of this study was to develop an effective omeprazole buccal a dhesive tablet with excellent bioadhesive force and good drug stability in human saliva. The omeprazole buccal adhesive tablets were prepared with var ious bioadhesive polymers, alkali materials, and croscarmellose sodium. The ir physicochemical properties, such as bioadhesive force and drug stability in human saliva, were investigated. The release and bioavailability of ome prazole delivered by the buccal adhesive tablets were studied. As bioadhesi ve additives for the omeprazole tablet, a mixture of sodium alginate and hy droxypropylmethylcellulose (HPMC) was selected. The omeprazole tablets prep ared with bioadhesive polymers alone had bioadhesive forces suitable for a buccal adhesive tablet, but the stability of omeprazole in human saliva was not satisfactory. Among alkali materials, only magnesium oxide could be an alkali stabilizer for omeprazole buccal adhesive tablets due to its strong water proofing effect. Croscarmellose sodium enhanced the release of omepr azole from the tablets; however, it decreased the bioadhesive forces and st ability of omeprazole tablets in human saliva. The tablet composed of omepr azole/sodium alginate/HPMC/magnesium oxide/croscarmellose sodium (20/24/6/5 0/10 mg) could be attached on the human cheek without disintegration, and i t enhanced the stability of omeprazole in human saliva for at least 4 h and gave fast release of omeprazole. The plasma concentration of omeprazole in hamsters increased to a maximum of 370 ng/ml at 45 min after buccal admini stration and continuously maintained a high level of 146-366 ng/ml until 6 h. The buccal bioavailability of omeprazole in hamsters was 13.7% +/- 3.2%. These results demonstrate that the omeprazole buccal adhesive tablet would be useful for deliver of an omeprazole that degrades very rapidly in acidi c aqueous medium and undergoes hepatic first-pass metabolism after oral adm inistration.