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Aim: This study aims to design a novel thiolated κ-carrageenan (κ-CA-SH) and evaluate its potential as an excipient for the design of mucoadhesive drug delivery systems. Methods: Native κ-carrageenan (κ-CA) was thiolated with phosphorous pentasulfide in sulfolane and characterized via 1H NMR, FTIR, as well as Ellman's test. Cytotoxicity was assessed via resazurin assay. In vitro release of the model drug, benzydamine hydrochloride, was determined. Tensile and mucosal residence time studies were performed on buccal and small intestinal mucosa. Mucoadhesive features were investigated via rheological studies with freshly isolated porcine mucus. Results: Thiolated κ-CA (κ-CA-SH) with 1213.88 ± 52 µmol/g thiol groups showed no cytotoxicity at a concentration of 1% (m/v) and low cytotoxicity up to 2% (m/v). Benzydamine hydrochloride showed slow release in solution for both polymers. Tensile studies on buccal and intestinal mucosa showed an up to 2.7-fold and 7.7-fold enhancement in the maximum detachment force (MDF) and total work of adhesion (TWA) of κ-CA-SH vs. κ-CA, respectively. The κ-CA-SH exhibited an up to 4.4-fold improved dynamic viscosity with mucus and significantly prolonged residence time on mucosa compared to native κ-CA. Conclusion: Since highly thiolated κ-CA shows a slow release of positively charged active pharmaceutical ingredients and enhanced mucoadhesive properties, it might be a promising excipient for local drug delivery in the oral cavity. [ABSTRACT FROM AUTHOR]

Aim: This study aims to design a novel thiolated κ-carrageenan (κ-CA-SH) and evaluate its potential as an excipient for the design of mucoadhesive drug delivery systems. Methods: Native κ-carrageenan (κ-CA) was thiolated with phosphorous pentasulfide in sulfolane and characterized via 1H NMR, FTIR, as well as Ellman’s test. Cytotoxicity was assessed via resazurin assay. In vitro release of the model drug, benzydamine hydrochloride, was determined. Tensile and mucosal residence time studies were performed on buccal and small intestinal mucosa. Mucoadhesive features were investigated via rheological studies with freshly isolated porcine mucus. Results: Thiolated κ-CA (κ-CA-SH) with 1213.88 ± 52 µmol/g thiol groups showed no cytotoxicity at a concentration of 1% (m/v) and low cytotoxicity up to 2% (m/v). Benzydamine hydrochloride showed slow release in solution for both polymers. Tensile studies on buccal and intestinal mucosa showed an up to 2.7-fold and 7.7-fold enhancement in the maximum detachment force (MDF) and total work of adhesion (TWA) of κ-CA-SH vs. κ-CA, respectively. The κ-CA-SH exhibited an up to 4.4-fold improved dynamic viscosity with mucus and significantly prolonged residence time on mucosa compared to native κ-CA. Conclusion: Since highly thiolated κ-CA shows a slow release of positively charged active pharmaceutical ingredients and enhanced mucoadhesive properties, it might be a promising excipient for local drug delivery in the oral cavity.

In this study, modified kappa‐carrageenan/pectin hydrogel patches were fabricated for treatment of buccal fungal infections. For this purpose, kappa‐carrageenan‐g‐acrylic acid was modified with different thiolated agents (L‐cysteine and 3‐mercaptopropionic acid), and the thiol content of the resulting modified kappa‐carrageenan was confirmed by elemental analyzer. Then, the hydrogel patches were fabricated, and characterized by Fourier‐transform infrared spectroscopy, thermogravimetric analysis, ex vivo mucoadhesion test, and swelling behavior. Triamcinolone acetonide was added either directly or by encapsulating within the poly(lactic‐co‐glycolic acid) nanoparticles. The release amount of the drug from the directly loaded patch was 7.81 mg/g polymer, while it was 3.28 mg/g polymer for the encapsulated patch with the same content at 7 hr. The hydrogel patches had no cytotoxicity by cell culture studies. Finally, the drug loaded hydrogel patches were demonstrated antifungal activity against Aspergillus fumigatus and Aspergillus flavus. These results provide that the novel modified kappa‐carrageenan and pectin based buccal delivery system has promising antifungal property, and could have advantages compared to conventional buccal delivery systems. [ABSTRACT FROM AUTHOR]