Buccal administration of human insulin in streptozocin-diabetic rats

This study investigates the use of the buccal route of administration in the delivery of human insulin in rats. Streptozocin-induced diabetic female Wistar rats were used in this study. Insulin (100 U) either free (i.e., insulin solution) or associated with a carrier, namely erythrocyte-ghosts (EG) and liposomes-vesicles (LEV), was administered buccally. Blood samples were collected from the tail over a period of 5 hr. These results indicate that insulin absorption occurred, as evidenced from a decrease in blood glucose concentration, and in the case of free insulin and erythrocyte-ghosts-insulin (EG-INS). The magnitude of the blood glucose level decline was at its maximum of 39.53 mg/dl (at 2 hr) and 26.23 mg/dl (at 4 hr) for free insulin and EG-INS, respectively. No significant difference in the blood glucose level profile was observed after either LEV or liposomes-vesicles-insulin (LEV-INS). This study demonstrates the ability of human insulin to be absorbed from the mouth cavity when it is instilled in the form of a simple solution or EG-INS suspension. This absorption resulted in a definite pharmacological effect but not a significant therapeutic effect.