Mucoadhesive approach for buccal application: Preactivated chitosan

Abstract

Buccal adhesive drug delivery has gained pharmaceutical interest in the past decades. This study aimed to establish an efficient mucoadhesive dosage form based on chitosan for the potential use in buccal application. Mercaptonicotinic acid (MNA) was covalently linked to chitosan via amide bond formation between the primary amino groups of chitosan and the carboxylic acid moieties of mercaptonicotinic acid. In a second step, obtained sulfhydryl linked chitosan was preactivated with the formation of disulfide bonds between chitosan-MNA and mercaptonicotinic acid (MNA). Preactivated chitosan-MNA-MNA conjugates were characterized in terms of degree of substitution and stability. Furthermore, whirling medium assay was performed on mucosal tissue. Chitosan-MNA-MNA convinced with its 18.8-fold enhanced stability of the polymeric matrix compared to unmodified chitosan. Moreover, adhesive properties were 12.56-fold improved in presence of chitosan-MNA-MNA in comparison to respective chitosan. All conjugates showed no toxicity to the cells. Taken together, synthesis of chitosan-MNA-MNA established a promising mucoadhesive dosage form for buccal application.