Sheep insulin administration

Ilium et al. [49] evaluated chitosan solutions as delivery platforms for nasal administration of insulin to rats and sheep. They reported a concentration-dependent absorption-enhancing effect with minimal histological changes of the nasal mucosa in all concentrations applied. 

The nasal absorption of insulin after administration in chitosan powder was the most effective formulation for nasal delivery of insulin in sheep compared to chitosan nanoparticles and chitosan solution [11], Similarly, chitosan powder formulations have been shown to enable an efficient nasal absorption of goserelin in a sheep model where bioavailabilities of 20-40% were obtained depending on the nature of the formulation [9],... 

To increase the residence time in the nasal mucosa, a bioadhesive formulation may be one of the most reasonable approaches. In fact, microspheres containing bioadhesive polymers such as starch, albumin, and Sephadex with a particle size of 40-60 pm have been found to be cleared from the nasal cavity much more slowly than solutions. Starch microspheres improved the nasal absorption of insulin, with synergistic effects of some absorption enhancers in sheep. In another paper, dry powder containing starch and Carbopol 974P showed significantly higher bioavailability after nasal administration than the formulation without Carbopol. ° Chitosan, already mentioned above, also has a bioadhesive property and is found to be useful as a potent absorption enhancer for nasal peptide delivery. Other bioadhesive polymer systems,... 

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