Problems and opportunities in the topical treatment of infectious diseases of the respiratory tract

Pneumonia is a major cause of morbidity and mortality in hospitalized patients. Topical antibiotics offer many potential advantages in the prevention and treatment of pneumonia in these patients. These include a high delivery of drug to the site of infection, and the potential for little systemic absorption with less toxicity than parenteral therapy. Previous clinical studies have produced mixed results, however. Emergence of resistant organisms and failure of the aerosol to penetrate into areas of diseased lung have been blamed for the failure of many previous studies to achieve positive results. In all of these studies, however, little attention has been paid to the delivery system, the dosage administered, the regional distribution in the lung, and the pharmacokinetics of the aerosol. Aerosolized pentamidine, however, has been studied with respect to the above factors, and has been shown to be clearly efficacious in the prevention of Pneumocystis carinii pneumonia. It should serve as a model for the testing of topical antibiotic therapy in other conditions.