Experimental intrabronchial administration of neomycin in man and animals.

Ten years ago, Waksman and Lechevaller1 demonstrated the important antibiotic action of neomycin against the Koch bacillus. The effect of neomycin is even greater than that of streptomycin. Rake, Hobby and Donovick' have also demonstrated the antibiotic effect of neomycin in experimental tuberculosis. Because of its toxicity, Grumbach and Rist3 considered that parenteral neomycin injection was dangerous. However, Dumon and Courtreux@ have shown that the blood concentration is minimal (injection of 0.33 gm. gives a maximum blood level of 1.6 microgram/mi.) afterintrabron chial administration. These workers describe good clinical results with toxic side effects following intrabronchial application. Previous investigations have shown that when streptomycin and oxy tetracycline are administered intrabronchially, their pulmonary concen tration is much higher for much longer periods than the level obtained after parenteral administration with the same dose.5 Therapeutic concentrations of chlortetracycline, tetracycline, and peni dillin are maintained for only five to six hours after administration. The pulmonary tissue concentration of erythromycin, and hydrazide (INH), as well as sulfathiazole, immediately after intrabronchial, is similar to the low content found after parenteral or oral application.6 This is indica tive of a higher diffusion rate from the point of application. In order to study this application method, for neomycin, we admin istered it both intrabronchially and parenterally in patients, and intra tracheally in guinea pigs and rabbits. Intrabronchial administration was effected by means of catgut tubes, since aerosols gave less satisfac tory results. The pulmonary tissue concentration of all the subjects was determined after various time intervals.