Intranasal bioavailability of insulin from carbopol-based gel spray in rabbits

The purpose of this study was to investigate the nasal absorption of insulin from a carbopol-based nasal gel spray in rabbits. An insulin nasal gel was prepared by dispersing carbopol in distilled water, followed by the addition of insulin solution, then neutralization and viscosity adjustment. The nasal absorption of insulin from the gel, in conscious rabbits, was evaluated in comparison with absorption from an insulin solution. The absolute bioavailability of insulin from the nasal gel was studied using blood glucose level in comparison to intravenous injection. The insulin gel formulation produced a significant hypoglycemic response in rabbits, whereas no response was seen following administration of the insulin solution formulation. The bioavailability of insulin from the nasal gel formulation was 20.6% compared with the intravenous injection. The results of the present study suggest that the carbopol gel promotes the nasal absorption of insulin in rabbit model and due to its sprayability with commercially available spray pumps, could be considered as a preferred platform in nasal drug administration.