Preactivated thiolated pullulan as a versatile excipient for mucosal drug targeting
Aim The purpose of the present study was to generate a novel mucoadhesive thiolated pullulan with protected thiol moieties and to evaluate its suitability as mucosal drug delivery system.
Methods Two different synthetic pathways: bromination-nucleophilic substitution and reductive amination including periodate cleavage were utilized to synthesize such thiolated pullulans. The thiomer (pullulan-cysteamine) with the highest amount of free thiol groups was further enrolled in a reaction with 6-mercaptonicotinamide and its presence in pullulan structure was confirmed via NMR analysis. Furthermore, unmodified, thiolated and preactivated thiolated pullulan were investigated in terms of mucoadhesion via rotating cylinder studies and rheological synergism method as well as their toxicity potential over Caco-2 cells.