Nasal residence of insulin containing lyophilised nasal insert formulations, using gamma scintigraphy

Bioadhesive dosage forms are a potential method for overcoming rapid mucociliary transport in the nose. A lyophilised nasal insert formulation previously investigated in sheep demonstrated prolonged absorption of nicotine hydrogen tartrate suggestive of extended nasal residence, and increased bioavailability. The current study was performed to quantify nasal residence of the formulations using gamma scintigraphy, and to investigate the absorption of a larger molecule, namely insulin. A four-way crossover study was conducted in six healthy male volunteers, comparing a conventional nasal spray solution with three lyophilised nasal insert formulations (1–3% hydroxypropylmethylcellulose (HPMC)). The conventional nasal spray deposited in the posterior nasal cavity in only one instance, with a rapid clearance half-life of 9.2 min. The nasal insert formulations did not enhance nasal absorption of insulin, however an extended nasal residence time of 4–5 h was observed for the 2% HPMC formulation. The 1% HPMC insert initially showed good spreading behaviour; however, clearance was faster than for the 2% formulation. The 3% HPMC nasal insert showed no spreading, and was usually cleared intact from the nasal cavity within 90 min. In conclusion, the 2% HPMC lyophilised insert formulation achieved extended nasal residence, demonstrating an optimum combination of rapid adhesion without over hydration.