Abstract
Purpose. To develop a novel mucoadhesive polymer that protects peptide drugs from degradation by secreted as well as membrane-bound proteases in the intestine, and to evaluate this polymer in vitro.
Methods. The serine protease inhibitors antipain, chymostatin and elastatinal were covalently linked to chitosan (poly-[l 4]-β-D-glucosamine). Thereafter, the complexing agent ethylenediaminete-traacetic acid (EDTA) was bound to the remaining primary amino groups of the polymer. The inhibitory effect of the resulting polymer-conjugate towards trypsin (EC 3.4.21.4), chymotrypsin (EC 3.4.21.1), elastase (3.4.21.36), carboxypeptidase A (EC 3.4.17.1), carboxypeptidase B (EC 3.4.17.2) and aminopeptidase N (EC 3.4.11.2) as well as its mucoadhesive properties were evaluated in vitro.
Results. Whereas the novel polymer-conjugate exhibited excellent swelling properties, its adhesive force was under our assay conditions 42% lower than that of unmodified chitosan. However, the polymer-conjugate showed a strong inhibitory activity towards all tested serine proteases. Due to its additional high binding affinity towards bivalent metal ions, it also inhibited the Zn2+-dependent exopeptidases carboxypeptidase A, B and aminopeptidase N.
Conclusions. The novel mucoadhesive polymer-conjugate described in this study seems to be a useful tool in overcoming the enzymatic barrier to perorally administered therapeutic peptides and proteins.
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Bernkop-Schnürch, A., Scerbe-Saiko, A. Synthesis and In Vitro Evaluation of Chitosan-EDTA-Protease-Inhibitor Conjugates Which Might Be Useful in Oral Delivery of Peptides and Proteins. Pharm Res 15, 263–269 (1998). https://doi.org/10.1023/A:1011970703087
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DOI: https://doi.org/10.1023/A:1011970703087