Serum tobramycin levels following delivery of tobramycin (Tobi®) via eFlow® advanced nebuliser in children with cystic fibrosis

BackgroundSafety and toxicity data for nebulised tobramycin are mainly derived from use of the Pari LC® Plus nebuliser, yet many centres are now using advanced nebulisers, such as the eFlow®.MethodsTen children (ages 2–16 years) receiving 300 mg TOBI® via eFlow® for clinical reasons participated. Serum tobramycin levels were obtained 1 h post nebulisation. Nine provided samples for urinary NAG, and 10 underwent audiology.ResultsTobramycin levels were > 1 mg/L in 3 children (maximum 3.8, 2 children aged 2 years). Urine NAG/creatinine levels were raised (> 0.94 μmol/min/mmol) in 5 children, 1 of these had a tobramycin level of > 1 mg/L. One patient had high frequency hearing loss.ConclusionSerum tobramycin levels over 1 mg/L can occur 1 h post 300 mg TOBI® delivered by eFlow®. Raised urinary NAG levels suggest that some children may have some associated early renal toxicity.