INTRADUODENAL ADMINISTRATION OF BIOCARRIER-INSULIN SYSTEMS

Successful oral administration of insulin for systemic therapeutic eff ects has long been a major pharmaceutical challenge. Intraduodenal adm inistration of insulin to rats, free or in a form of carrier-insulin, was the subject of this study. Several erythrocyte-membrane carrier sy stems (ghosts, vesicles, liposomes-ghosts, and liposomes-vesicles) wer e tested. Insulin (100 U) was incubated with each of the carriers at 3 7-degrees-C for 24 hr. The carrier-insulin system, insulin solution, s odium chloride solution, or carrier-free insulin was then introduced i nto the duodenum of anesthetized male Wistar diabetic rats. Blood samp les were collected from the tail at different time intervals and then analyzed for glucose content using an o-toluidine method. There was no significant difference in blood glucose concentrations among the cont rol groups. However, ghosts-insulin, vesicles-insulin, and liposomes-v esicles-insulin all showed a statistically significant difference in l owering blood glucose levels when compared to control groups. Liposome s-ghosts-insulin did not show any significant difference from its cont rol group. The results indicate that liposomes-vesicles-insulin was th e most efficient in delivering insulin into the circulation in its pha rmacologically active form of, any other carrier tested. The findings of this study may be of significance in the search for a suitable oral carrier for insulin or perhaps other proteinaceous substances.