Serum and lower respiratory tract drug concentrations after tobramycin inhalation in young children with cystic fibrosis

Objectives: To assess the serum and lower respiratory tract tobramycin concentrations (CT) produced by a single dose of tobramycin for inhalation delivered by a nebulizer and a compressor in patients with cystic fibrosis (CF) 6 months to 6 years of age. Study design: We performed a dose escalation study of serum CT measured before and 0.5, 1, 2, and 4 hours after a single dose of inhaled tobramycin, either 180 mg (10 patients) or 300 mg (19 patients). In a separate group of 12 patients, epithelial lining fluid (ELF) CT was measured by bronchoalveolar lavage 30 to 45 minutes after a 300-mg dose. Results: A 180-mg dose of inhaled tobramycin produced a mean peak serum CT of 0.5 μg/mL (SD 0.4; range,