Background: Introducing the concept of mucoadhesion in the 1980s, application of mucoadhesive polymers for buccal drug delivery has been the subject of pharmaceutical interest. Aim: The purpose of this study was to modify well-known xanthan in order to remarkably boost its suitability for buccal adhesiveness. Method: Xanthan (X) was chemically modified by covalent binding of L-cysteine (SH) exhibiting sulfhydryl groups on the polymeric backbone via amide bond formation. Cytotoxicity, stability properties and mucoadhesiveness, respectively, of sulfhydryl-modified xanthan (H-SH) was investigated compared with unmodified xanthan (X). Results: According to cell viability studies X-SH was safe to use. X-SH revealed 1.61-fold higher stability in comparison to unmodified xanthan. Thereafter, mucoadhesion of X-SH augmented 8.35-fold in case of rotating cylinder assay. Tensile study showed 2.65-fold higher total work of adhesion when comparing X-SH with X. Conclusion: In completion, novel sulfhydryl-modified xanthan proved itself being a useful and promising excipient for buccal-adhesive delivery systems.

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