The nasal route, advanced drug delivery systems and evaluation: a review

Abstract
Nasal drug delivery is a well-known alternative to oral and parenteral drug delivery systems. Protein, peptides, hormones, and vaccines are the sensitive molecules for the oral route; hence those can be reached via nasal delivery. The nasal way has several advantages: higher permeability, more vasculature, less contact with enzymes due to less nasal space, and no hepatic first-pass metabolism. Therefore, it is a suitable route for sensitive drug molecules. Different applicators can deliver solid, liquid, and semisolid formulations for treating various diseases. The present review considers a brief introduction to the nasal route and problems associated with the nasal course for drug delivery, conventional and novel formulations, their applications, and evaluation parameters. Moreover, some of the marketed formulations for the nasal route of drug delivery systems and patented technologies are tabulated by reviewing the previous and updated literature.