Deposition of Aerosolized Lucinactant in Nonhuman Primates.

Background: Lucinactant for inhalation is an investigational noninvasive, aerosolized surfactant replacement therapy for treatment of preterm neonates with respiratory distress syndrome. Lucinactant for inhalation consists of lyophilized lucinactant and the Aerosurf® Delivery System (ADS). The objective of this study was to characterize the total and regional pulmonary deposition of lucinactant delivered by the ADS in nonhuman primates (NHPs). Methods: Lucinactant was radiolabeled by the addition of technetium-99m (99mTc)-sulfur colloid. The radiolabeled aerosol was characterized and validated using a Mercer cascade impactor. An in vivo deposition study was performed in three cynomolgus macaques. Radiolabeled lucinactant was aerosolized using the ADS and delivered via nasal cannula under 5 cm H2O nasal continuous positive airway pressure (nCPAP) for 5-9 minutes. A two-dimensional planar image was acquired immediately after aerosol administration, followed by a three-dimensional single-photon emission computed tomography (SPECT) image and a second planar image. The images were analyzed to determine the pulmonary (lungs) and extrapulmonary (nose + mouth, trachea, stomach) distribution. The SPECT data were used to determine regional deposition. Results: The radiolabed lucinactant aerosol had a mass median aerodynamic diameter = 2.91 µm, geometric standard deviation (GSD) = 1.81, and an activity median aerodynamic diameter = 2.92 µm, GSD = 2.06. Aerosolized lucinactant was observed to deposit in the lungs (11.4%), nose + mouth (79.9%), trachea (7.3%), and stomach (1.4%). Analysis of the SPECT image demonstrated that the regional deposition within the lung was generally homogeneous. Aerosolized lucinactant was deposited in both the central (52.8% ± 1.2%) and peripheral (47.2% ± 1.2%) regions of the lungs. Conclusion: Aerosolized lucinactant, delivered using the ADS via constant flow nCPAP, is deposited in all regions of the lungs demonstrating that surfactant can be aerosolized and delivered noninvasively to NHPs.