Rheological study on mucoadhesivity of some nasal powder formulations.

Various powder mixtures were used to administer insulin via the nasal route: a co-spray dried mixture of Amioca starch and Carbopol 974 P (1/3), drum dried waxy maize starch and Carbopol 974 P (9/1), maltodextrin DE38/Carbopol 974 P (9/1) and pure drum dried waxy maize starch. Oscillatory rheology is performed to study and compare the viscosity, elasticity and mucoadhesivity of these powder formulations. There was no rheological synergism detectable with the co-spray dried mixture of Amioca starch and Carbopol 974 P (1/3), drum dried waxy maize starch and Carbopol 974 P (9/1) and maltodextrin DE38/Carbopol 974 P (9/1). Interaction due to entanglements was seen with drum dried waxy maize starch (100%). The differences in nasal bioavailability between the different carriers could be explained by differences in G' (storage modulus, elasticity) and G" (loss modulus, viscosity) values. The formulation giving the highest bioavailability, provided also the highest G' and G" values.