Abstract: A surfactant can be added, safely and effectively, to a drug solution containing any antimicrobial agent, such as an antibiotic like tobramycin, that is suitable for administration to the lungs via inhalation. Thus, when an aerosolized drug solution includes surfactant, Marangoni flows cause the drug particles, once deposited in the lungs, to spread over a wider surface area, thereby ensuring greater antimicrobial efficacy. A solution that contains, for example, an antibiotic and tyloxapol or another surfactant providing a similar surface tension to the composition is optimally delivered by the functional combination of a breath-actuated nebulizer and a high-flow compressor.