Dissolving and swelling characteristics of different microsphere preparations.

(A) Cross-linking for 0.5 h. (B) Cross-linking for 1 h. (C) Cross-linking for 2 h. All black squared curves depicted by line and symbol represent the changes of swelling ratio and red circled curves show the changes of exenatide release. The experiments were conducted in 0.063 N HCl solutions (pH 1.2) for the first 2 h and then transferred to 0.1 M sodium phosphate solution (pH 7.4). Data are averages of three independent experiments and error bars represent standard deviations.