The bioavailability of insulin from a nasal formulation with 5% glycofurol (GF) was studied in vivo in rabbits. A pronounced decrease in the plasma glucose level, comparable to the response for Novolin Nasal, was observed. A nadir after 30 min was observed where the plasma glucose was 59% of the initial value. The potential for local side effect from 5% GF was found to be very low in the frog-palate model, where the mucociliary clearance rate was only reduced 9%.