Pulmonary Drug Delivery

Abstract

Publisher Summary In this chapter, a brief outline of the human respiratory system is provided, and mechanisms of drug particle deposition in human lungs, various pulmonary drug delivery (PDD) devices, and analytical methods associated with characterization of aerosols are also reviewed. An attempt has also been made to assess the challenges and opportunities of pulmonary drug delivery. The therapeutic advantages of selective targeting of drugs to the airways and lungs for the treatment of respiratory diseases are enormous, as are those of the emerging field of systemic delivery via the lung. The pulmonary route is one of the preferred drug delivery routes, since it provides a large surface area for rapid absorption provided by terminal bronchioles and alveoli, a thin (0.1–0.2 mm of alveolar epithelium) physical barrier for absorption, promoting rapid uptake into the bloodstream, and minimal extracellular enzyme levels for metabolic breakdown compared with the gastrointestinal tract. Because of the large surface area and rich blood supply, the pulmonary airway enables rapid onset of therapeutic action even with reduced doses compared to the oral and other systemic routes; therefore, systemic side effects are minimal. Current understanding of in vitro and in vivo relationships for PDD products are incomplete and still evolving, but the correlations showed that in vitro data can be used more widely as a means of comparing different inhaler devices during product development. Pulmonary drug formulation and delivery device technologies are advancing very rapidly, as the pharmaceutical industry moves to adopt the potential advantages of the pulmonary route as an alternative to oral and parenteral delivery methods.