[In vitro release kinetics and hypoglycemic effect on diabetic rats after oral administration of insulin loaded...

The insulin-loaded polyalkylcyanoacrylate nanoparticles (INS-NP) were made with Dextran 70 as the stabilizer. The mean diameter of INS-NP was 252.4 nm with a poly dispersity of 0.005. The associating ratio of insulin to the nanoparticles reached 70.1% +/- 2.3%, while the loading capacity was 0.14 u.mg-1. Studies on in vitro release kinetics showed that release profiles can be well modelled using a biexponential function. The burst effect was obvious, and a faster release was observed in acidic media. After various doses of INS-NP were intragastrically given to diabetic rats, significant decrease of glucose level was achieved in the 10 and 20 u.kg-1 groups, with no significant difference between these two doses. The relative bioavailability after p.o. administration of INS-NP 10 u.kg-1 over s.c. administration of insulin solution 1 u.kg-1 was 7.58% calculated by the area over the curve of glucose level (%) versus time profiles. The correlation was obvious between the % of insulin released at pH 7.0 and the % of glucose decreased within the first 7 hours. Hence, an oral insulin preparation with rather high bioavailability was provided in this study, and its shorter effective time will make it more convenient for the control of the glucose level in clinics.