Doxycycline concentrations in lung tissue, bronchial wall, and bronchial secretions.

Doxycycline levels were measured in 44 patients undergoing lung surgery; 44 determinations were made on serum, 37 on resected lung tissue, 11 on bronchial wall, and 8 on bronchial secretions. The concentrations in lung tissue were, with few exceptions, higher than the serum concentrations, while those in homogenized bronchial wall specimens were slightly lower than the serum readings. All these concentrations were on average considerably higher than the minimum inhibitory concentrations for the pneumococcus and Haemophilus influenzae. The comparatively low bronchial secretion concentrations were accounted for by the surgical circumstances. All patients had been intensively trated pre-operatively, and showed no florid mucosal inflammation at the time of the operation: as inflammation subsides, so the antibiotic concentration in the bronchial secretion declines rapidly. The lung and bronchial wall tissue levels indicate that doxycycline has great promise in the treatment of pulmonary and bronchial disorders.