Effects of sperminated polymers on the pulmonary absorption of insulin

Sperminated pullulans (SP) and gelatin (SG) having different numbers of amino groups were prepared as sperminated polymers for absorption enhancement and the absorption-enhancing effects on the pulmonary absorption of insulin in rats and the permeation of FITC-dextran (MW 4400, FD4) through Calu-3 cell monolayers were evaluated. In both in vivo and in vitro experimental systems, SP and SG acted as enhancers and their enhancing effects correlated with the amino group content. The zeta potential of red blood cells treated with SP and SG was positive and the degree was also correlated with the amino group content. SP and SG interact directly with the luminal surface of mucus membranes via an ion-ion interaction and then may induce signals that open tight junctions resulting in intercellular permeation of water soluble drugs.