Therapeutic Drug Monitoring of Inhaled Tobramycin in a Post-Hematopoietic Cell Transplant Patient With Bronchiolitis Obliterans and End-Stage Renal Disease.

There are no widely accepted dose alterations for inhaled tobramycin in the setting of renal dysfunction, and serum concentrations are not typically monitored. Herein we describe a case report of a 16-year-old female with a history of 2 hematopoietic cell transplants and a kidney transplant who received inhaled tobramycin for chronic management. The patient developed chronic kidney disease, and tobramycin concentrations were monitored. Initially she received a reduced dose of inhaled tobramycin, with repeated doses based on serum concentrations. The dose was increased, but serum concentrations obtained the following day remained higher than desired, leading to a suspicion of delayed systemic absorption. Tobramycin administration was changed from immediately prior to dialysis to the evening prior to the next day's dialysis session, and serum concentrations were consistently <1 mg/L postdialysis. In conclusion, systemic absorption of inhaled tobramycin in non-cystic fibrosis (CF) patients may differ compared to that observed in CF patients. Renal dysfunction may lead to systemic accumulation of inhaled tobramycin, and the timing of inhaled tobramycin administration with respect to dialysis has a potentially significant influence on drug clearance. Thus, monitoring may be required. Further cases are required to verify these observations.