Endocrine Abstracts

In type 1 diabetes mellitus, tight glycaemic control is required to attenuate chronic complications and often requires daily injectable insulin therapy, which can result in non-compliance because of patient discomfort. As a result of this, some studies are concerned with optional routes of insulin administration. In our laboratory, we have developed amidated pectin (polygalacturonic acid) hydrogel beads for oral insulin administration. The aim of present was to investigate whether insulin can be transported through the skin using pectin hydrogel insulin patches. Four groups of diabetic male Wistar rats (n=10) fasted overnight were used. Basal blood glucose concentrations were taken and the patches (containing 6, 15, 30 and 60 μg of insulin in each group, respectively) applied before the administration of an oral glucose tolerance test (OGTT) (0.86 g of glucose/kg body weight). Blood glucose was measured using the tail-prick method at 30 min, 1, 2, 3 and 4 h after glucose administration. After 4 h, rats were sacrificed and blood collected for plasma insulin assay using the rat ultra-sensitive insulin ELISA. The patches were dissolved in Sorenson’s buffer and the insulin released measured by ELISA. At each time point during the OGTT, the blood glucose concentration was significantly lower in the high insulin dose group than the low insulin dose groups, indicating that insulin was transported across the skin and that a dose-dependant effect on blood glucose occurred. Similarly, plasma insulin concentrations after 4 h were 18.7±4.9, 26.9±3.9, 35.7±2.6 and 112.7±9.1 pmol/l for the 6, 15, 30 and 60 μg insulin patch group, respectively. The dissolution studies revealed an insulin yield from the patches of greater than 70%. Results of this study suggest that transdermal insulin delivery using pectin hydrogel patches occurs in a rat model of type 1 diabetes mellitus.