title: Polymer integrity related absorption mechanism of superporous hydrogel containing interpenetrating polymer networks for oral delivery of insulin.
abstract: Superporous hydrogel containing poly(acrylic acid-co-acrylamide)/O-carboxymethyl chitosan interpenetrating polymer networks (SPH-IPN) was evaluated as the oral delivery vehicle for insulin, emphasizing on the effect of polymer integrity on insulin absorption mechanisms. The integral SPH-IPN (I-SPH-IPN) and powdered SPH-IPN (P-SPH-IPN) exhibited potent and equivalent in vitro enzymatic inhibition capacities, which were attributed to both enzyme incorporation and Ca(2+) deprivation. Nevertheless, I-SPH-IPN showed marked superiority to P-SPH-IPN in in vivo enzymatic inhibition. Through reversible opening of epithelial tight junctions, I-SPH-IPN notably enhanced paracellular permeability of insulin in Caco-2 cell monolayers and excised rat intestine by 4.9 and 4.2 folds, respectively, wherein I-SPH-IPN outperformed P-SPH-IPN by 2.5 and 2.3 folds, respectively. Besides, orally delivered I-SPH-IPN could retain in rat intestine for more than 8 h while P-SPH-IPN was quickly eliminated, suggesting better retentive properties of I-SPH-IPN. Such results were further confirmed by in vivo assessment in that oral administration of insulin-loaded I-SPH-IPN yielded notable insulin absorption and hypoglycemic effect, while P-SPH-IPN was ineffective. Finally, an oral acute and sub-acute toxicity study in mice confirmed biocompatibility of SPH-IPN. Therefore, the detailed mechanism assessment confirmed that I-SPH-IPN was an effective and safe peroral carrier for protein drugs.
authors.affiliation: State Key Laboratory of Genetic Engineering, Department of Pharmaceutical Sciences, School of Life Sciences, Fudan University, Shanghai, China.
authors.forename: Lichen
authors.initials: L
authors.lastname: Yin
authors.forename: Jieying
authors.initials: J
authors.lastname: Ding
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Chunbai
authors.initials: C
authors.lastname: He
authors.forename: Cui
authors.initials: C
authors.lastname: Tang
authors.forename: Chunhua
authors.initials: C
authors.lastname: Yin
mesh_terms: D000284:Administration, Oral; D000327:Adsorption; D000818:Animals; D018938:Caco-2 Cells; D006801:Humans; D020100:Hydrogels; D007082:Ileum / Q000378:metabolism; D007328:Insulin / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008297:Male; D011108:Polymers / Q000737:chemistry*; D051381:Rats
chemical_list: D020100:Hydrogels; D007328:Insulin; D011108:Polymers