Purpose:

To evaluate dosing strategies used and systemic levels achieved of inhaled tobramycin in pediatric patients without cystic fibrosis (CF)

Methods:

A retrospective single-center chart review was performed to assess the percentage of patients treated with inhaled tobramycin who achieved detectable serum tobramycin levels and the percentage of patients with tobramycin levels greater than 1 mcg/ml (indicating potential risk for aminoglycoside toxicity). Cases of detectable serum tobramycin levels were then evaluated to determine the presence of any possible relationships between detectable levels and patient specific factors, including age, inhaled tobramycin dose, concomitant medications and renal function.

Results:

Between August 2004 and August 2013, 12 non-CF pediatric abdominal transplant patients at our institution who received inhaled tobramycin for either prevention or treatment of bacterial lung infections were identified. Eleven of the 12 patients were post multi-visceral transplant and 1 patient was post-kidney transplant. Variable inhaled tobramycin dosing strategies were utilized during the study period, including 300 mg BID and lower-dose regimens. Of the 12 transplant patients who received inhaled tobramycin during the study time period, 9 patients (75%) had at least one systemic level drawn. Four of the 9 patients (44%) had a detectable tobramycin level at one point during their therapy, and 2 patients (22%) had serum tobramycin levels >1 mcg/ml. Three of the 4 patients with detectable levels were concomitantly receiving other potential nephrotoxic medications (vancomycin and/or tacrolimus), but no patients were actively receiving renal replacement therapy or met pediatric RIFLE criteria for any stage of renal impairment. Response to the elevated levels included increased monitoring (2 patients), decreased tobramycin dose (1 patient) and discontiuation of inhaled tobramycin therapy (1 patient).

Conclusions:

Inhaled tobramycin therapy in non-CF pediatric transplant patients can be associated with detectable serum tobramycin levels. Periodic monitoring of levels in transplant patients receiving inhaled tobramycin may be warranted, especially in patients at high risk for renal impairment.

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