EFFECT OF POLYMERS AND MICROSPHERES ON THE NASAL ABSORPTION OF INSULIN IN RATS

Dextran microspheres and polymer solutions have been evaluated as potential vehicles for nasal administration of insulin in rats. The polymer solutions were either viscous (polyacrylic acid and sodium hyaluronate) or showed thermal gelation (poly-N-isopropylacrylamide and ethyl(hydroxyethyl)cellulose). The spheres were epichlorohyrin cross-linked dextran, Sephadex and DEAE-Sephadex. Administration of insulin at 1 IU/kg caused a significant decrease in plasma glucose level with two of the investigated polymer systems, polyacrylic acid and ethyl(hydroxyethyl)cellulose, and with the Sephadex spheres. Sodium hyaluronate and poly-N-isopropylacrylamide exerted a significant influence on the plasma glucose level when used as vehicle for an insulin dose of 5 IU/kg. Insulin in DEAE-Sephadex had no effect at all on the plasma glucose level. A larger reduction in plasma glucose level was observed with insulin carried in the particle system than in the polymer systems. Powder formulations which take up water and swell appear to be more efficient in promoting absorption of insulin than the polymer systems.