The lung is an attractive target for drug delivery due to noninvasive administration via inhalation aerosols, avoidance of first-pass metabolism, direct delivery to the site of action for treating respiratory diseases, and the availability of a huge surface area for local drug action and systemic absorption of the drug. Nanocarrier systems in pulmonary drug delivery offer many advantages such as the potential to achieve uniform distribution of drug dose among the alveoli, achievement of improved solubility of the drug from its aqueous solubility, a sustained drug release which consequently reduces dosing frequency, improves patient compliance, decreases the incidence of side effects, and the potential of drug internalization by cells. This review focuses on the different nanocarrier systems used in pulmonary drug delivery with special attention to their pharmaceutical aspects.
. Additionally, drug metabolism in the lung is lower compared to the normal oral pathway due to low intra- and extracellular enzymatic activity in the lung (3-5) that helps the drug bypass the first-pass liver metabolism