Nanoparticulate systems for nasal delivery of drugs: A real improvement over simple systems?

This review discusses the possible benefits of using nanoparticles for nasal delivery of drugs and vaccines. It considers the various factors affecting particle transport across the nasal tissue. The evidence for the improved transport of drugs, such as peptides and proteins, across the nasal epithelium when formulated in a nanoparticulate system, as compared to an optimal solution formulation, is not convincing. For instance it has been shown that a chitosan solution and especially a chitosan powder formulation was superior in enhancing the nasal absorption of insulin as compared to chitosan nanoparticles. On the other hand, the use of nanoparticles for vaccine delivery seems beneficial in that good immune responses are achieved. This could be due to the fact that small particles can be transported preferentially by the lymphoid tissue of the nasal cavity (NALT). However, apparently no studies have been published comparing directly other adjuvant nasal systems with nanoparticulate systems. (c) 2006 Wiley-Liss, Inc. and the American Pharmacists Association.