Chitosan coated niosomes for nose-to-brain delivery of clonazepam: Formulation, stability and permeability studies.

Crossing the Blood Brain Barrier constitutes a challenge in drug administration to the brain. In this context, nose-to-brain delivery is explored as an alternative route in the treatment of central nervous system disorders, and nanotechnology constitutes a promising tool for drug delivery to the brain. In this work, we explored niosomes and chitosan-coated niosomes (chitosomes) as possible tools for nose-to-brain delivery of clonazepam. The formulations have been optimised using different chitosan concentrations and different preparation methods as Thin Layer Evaporation-paddle (TLE-P), Evaporation (E), and Solvent Displacement Technique (SDT). The most suitable formulations were loaded with clonazepam (CLZ) and a full physicochemical characterization was performed. Chitosomes presented a size of around 200 nm, PDI < 0.3, a positive surface charge, spherical shape and a CLZ encapsulation above 60%. Chitosomes were stable for 12 weeks under storage conditions at 4ºC, in simulated nasal fluid for 24 h as well as after a lyophilization-sonication process. A CLZ release of 50% was also achieved after 4 h in this media. The mucoadhesive properties of chitosomes were also confirmed, with a 1.5-fold reduction of CLZ toxicity after encapsulation and a 10-fold increase of its permeability.