Next generation of buccadhesive excipient: Preactivated carboxymethyl cellulose.

Aim: Assessment of preactivated carboxymethyl cellulose as potential excipient for buccal drug delivery.

Methods: Firstly, carboxymethyl cellulose (CMC) and cysteine (SH) were covalently coupled via amide bond formation to obtain thiolated carboxymethyl cellulose (CMC-SH). Further, preactivated carboxymethyl cellulose (CMC-S-S-MNA) was obtained by preactivation with 2-mercaptonicotinic acid (MNA). Sulforhodamine 101 (SRH101) was used as a model drug for permeation study through buccal mucosa. CMC-S-S-MNA was evaluated with respect to mucoadhesive and permeation enhancing effect and cytotoxicity.

Results: Thiolated carboxymethyl cellulose exhibited a total amount of 112.46 ± 0.46 thiol groups. CMC-S-S-MNA exhibited around 50% of preactivated thiol groups. The preactivated polymer showed no toxic effect. Furthermore, compared to unmodified CMC, CMC-S-S-MNA revealed 3.0-fold improved mucoadhesive properties according to the rotating cylinder method and 8.8-fold enhancement in mucoadhesiveness by tensile assay, respectively.

Conclusion: Preactivated carboxymethyl cellulose fulfills the requirements as potential excipient of being mucoadhesive and permeation enhancing for the buccal drug delivery.