Tissue levels of doxycycline in the human lung and pleura

Antibiotic concentrations in the human lung and pleural tissue were measured following intravenous administration of doxycycline. The average serum levels were 9.3, 7.0 and 3.0 micrograms/ml at 1, 2, and 3 hours; correspondingly, the lung tissue levels were 6.8, 3.5 and 2.3 micrograms/g. The pleural tissue antibiotic concentrations at the same time intervals were 2.5, 1.5, and 1.5 micrograms/g. This suggests that doxycycline is retained well by the lung and the pleura, well above the minimal inhibitory concentration of most of the common bacterial pathogens of the lung, and may be used in the treatment of lung infections caused by susceptible organisms.