Aminoglycosides cystic fibrosis infections

Newer examples of aminoglycoside antibiotics include amikacin, neomycin (Neosporin, Cortisporin), and tobramycin (TOBI, TobraDex). Injectable tobramycin is used in the treatment of serious infections at many body sites. It has also been formulated in an inhalable dosage form that has a very specific use to treat cystic fibrosis patients having Pseudomonas aeruginosa lung infections. In the form suitable for inhalation by the patient, it delivers the antibiotic directly to the site of infection. 

The search for useful inhaled antibiotics has been driven, in part, by a concern about the adequacy of systemic antimicrobial therapy for respiratory infections. Some agents, including aminoglycoside antibiotics, exhibit limited penetration into respiratory tract secretions. In fact, aminoglycosides may achieve sputum concentrations that are 12% of related serum concentrations. In addition, cystic fibrosis patients are often colonized with mucoid strains of Pseudomonas aeruginosa. This phenotype is associated with a further reduction in penetration of antibiotics. 

Initial experiences with aerosolized antimicrobial therapies appeared in the literature more than 50 years ago. Until the early 1990s, the quality of the evidence supporting this strategy in the management of lung infections was poor. Recently, results from well-controlled clinical trials have established a role for inhaled antibiotics, particularly aminoglycosides, as suppressive therapy for patients with cystic fibrosis. Cyclic therapy with inhaled tobramycin reduces the frequency of pulmonary exacerbations and improves lung function. 

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