Cholic Acid-Grafted Thiolated Chitosan-Enveloped Nanoliposomes for Enhanced Oral Bioavailability of Azathioprine: In Vitro and In Vivo Evaluation.

The purpose of the present study was to develop a cholic acid-grafted thiolated chitosan (CA-CS-TGA) polymeric biomaterial for attaining improved permeation via attaching thiol groups and cholic acid moieties. For this purpose, a CA-CS-TGA graft was prepared, and modification was confirmed via FTIR analysis. The prepared CA-CS-TGA graft was used to coat the azathioprine-loaded nanoliposomes (ENLs), with subsequent characterization in terms of zeta size, zeta potential, and SEM analysis. Pharmaceutical evaluation was carried out in terms of drug release studies, and ex vivo permeation and in vivo oral bioavailability were studied. The particle size and zeta potential of CA-CS-TGA coated nanoliposomal formulation CA-CS-TGA-NLs were found to be 245 ± 15.6 and +22.4 ± 0.58, respectively, compared to that of nonenveloped nanoliposomal formulation 165.7 ± 12.3 and -21.8 ± 0.14, respectively, indicating successful coating. CA-CS-TGA-NLs indicated 64% of drug release in 24 h at pH 7.4. Ex vivo permeation enhancement and relative oral bioavailability studies indicated a 2.84-fold enhanced permeation and 6-fold enhanced oral bioavailability of CA-CS-TGA-NLs compared to Azathioprine suspension. Based on the results, it can be concluded that grafting the CA-CS-TGA polymer onto nanoliposomes seems to be a promising strategy to enhance the oral bioavailability of Azathioprine.