This book addresses the recent trends and clinical research being reported in last 5 to 10 years in the field of nasal drug delivery systems. In recent years, interest in using nasal passage as drug absorption site has received increased attention from formulation scientists. Nasal passages, even though a small surface area of the body as compared to other absorption passage such as Gastrointestinal tract or skin, show significant possibility for drug absorption at a quicker rate. There is also a possibility of delivering drugs to the brain using this passage and targeting drugs through the nasal passage. The book has 19 chapters addressing various aspects of nasal drug delivery systems such as an overview of anatomy and physiology of the nasal passage from a drug delivery point of view to global market opportunities for nasal drug delivery. In between, it addresses various aspects of nasal drug delivery.