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Published on: December 23, 2016
Thiolated chitosans: influence of various sulfhydryl ligands on permeation-enhancing and P-gp inhibitory properties
Duangkamon Sakloetsakun1, Javed Iqbal, Gioconda Millotti
1Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria.
Purpose:
The influence of various sulfhydryl ligands on permeation-enhancing and P-glycoprotein (P-gp) inhibitory properties of the six established thiolated chitosan conjugates was investigated using Rhodamine-123 (Rho-123) and fluorescein isothiocyanate-dextran 4 (FD4) as model compounds.
Methods:
Permeation of these compounds was tested on freshly excised rat intestine in Ussing-type chambers. Apparent permeability coefficients (Papp) were calculated and compared to values obtained from the buffer only control.
Results:
The lyophilized polymers had a thiol group content in the range of 230-520 μmol/g. Results of this study led to the following rank order in permeation enhancement: chitosan-6-mercaptonicotinic acid (chitosan-6MNA) > chitosan-cysteine (chitosan-Cys) > chitosan-glutathione (chitosan-GSH) > chitosan-4-thiobutylamidine (chitosan-TBA) > chitosan-thioglycolic acid (chitosan-TGA) > chitosan-N-acetyl cysteine (chitosan-NAC). In P-gp inhibition studies, 0.5% (m/v) chitosan-NAC showed the highest inhibitory effect on P-gp, where the Papp was determined to be 3.78-fold increased compared with the buffer control. Among these thiolated chitosans, chitosan-NAC and chitosan-6MNA are the most effective polymers being responsible for P-gp inhibition and permeation enhancement, respectively.
Conclusion:
These thiolated chitosans would therefore be advantageous tools for enhancing the noninvasive bioavailability of active pharmaceutical ingredients.
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