A comparison of peak sputum tobramycin concentration in patients with cystic fibrosis using jet and ultrasonic nebulizer systems

Study objective: To determine whether adequate concentrations of a new formulation of tobramycin could be delivered to the lower respiratory tract of patients with cystic fibrosis (CF) using a jet nebulizer delivery system. Design: A multicenter, open-label, randomized, crossover study. Setting: Ten tertiary care, university-affiliated, teaching hospitals in the United States. Patients and control subjects: Sixty-eight patients recruited from 10 CF Foundation centers and who were at least 8 years of age, had a diagnosis of CF, and expectorated daily sputum. No control subjects enrolled. Interventions: Each patient received one administration of aerosolized tobramycin from each of the three nebulizer systems in random order. Each administration was separated by a minimum of 48 h. The two jet nebulizer systems tested were the Sidestream (Medic-Aid; Sussex, UK), and the Pari LC (Pari Respiratory Equipment; Richmond, Va), with a DeVilbiss Pulmoaide compressor (DeVilbiss Health Care; Somerset, Pa), both administering 300 mg tobramycin in 5 mL of 1/4 normal saline solution (NS), Patients were also administered 600 mg tobramycin in 30 mL of 1/2 NS with the UltraNeb 99/100 (DeVilbiss). Measurements: Sputum and serum tobramycin concentration and pulmonary function were monitored. An adequate peak sputum tobramycin concentration was defined as > 128 mu g/g sputum at any of three time points (10, 60, or 120 min) after completion of treatments. Results: The peak tobramycin concentrations in expectorated sputum were 687 +/- 663 mu g/g (mean +/- SD) with the Pari LC and 489 +/- 402 mu g/g with the Sidestream. Adequate peak sputum tobramycin concentration was achieved in 93% of the patients with the Sidestream, and in 87% of the patients with the Pari LC. Peak sputum concentrations were found to be substantially higher when patients received tobramycin administered with the UltraNeb 99/100, 1,498 +/- 1,331 mu g/g with 30% of patients having levels exceeding 2,000 mu g/g. Serum tobramycin concentrations were less than or equal to 4 mu g/mL for all patients following administration with each nebulizer. Conclusions: Adequately high sputum tobramycin concentrations were documented in sputum in >85% of patients following the administration of 300 mg/5 mL formulation of tobramycin aerosolized by the two jet nebulizer delivery systems, Sidestream and Pari LC. The single tobramycin administration delivered by these two systems is well-tolerated.