New insights into exogenous surfactant as a carrier of pulmonary therapeutics

As an organ system, the lung has unique advantages and disadvantages for localized drug delivery. Its direct contact with the external environment allows for the upper airways to be easily accessible to intrapulmonary delivery. However, its complex branching structure makes direct delivery to the peripheral airways challenging. This review will discus the utility of exogenous surfactant, a lipoprotein complex currently used to treat neonatal respiratory distress syndrome, as a carrier for pulmonary therapeutics to enhance the delivery of these drugs to the deeper regions of the lung. The focus is to provide an update on the many tools available to develop new surfactant-based therapeutics using computer modeling, in vitro approaches, and in vivo testing, which may ultimately lead to clinical trials. Two clinical conditions, Acute Respiratory Distress Syndrome and Bacterial Pneumonia are utilized throughout as prototypical examples of pulmonary conditions in which surfactant drug combination may be beneficial. Consequently, the pharmaceuticals discussed are primarily those with antimicrobial or anti-inflammatory activities.