Tobramycin as a Pharmacologic Tracer to Compare Airway Deposition from Nebulizers

Abstract

Tobramycin can be used as a pharmacologic tracer for comparison of relative airway deposition by nebulizers.

Nebulisers comparison with inhaled tobramycin in young children with cystic fibrosis

“…However, a long and variable terminal half life has been described after 600 mg tobramycin nebulisation in adults (mean 9.47 ± 3.28 h) [21]. In another study [17], 2 subjects out of 6 have detectable urinary tobramycin concentrations at or just above the limit of detection for each of the four 12-h collection intervals. These subjects were female and had the same pharmacokinetic profile with the 3 tobramycin doses tested (80, 160, and 320 mg) [17].…”

“…In another study [17], 2 subjects out of 6 have detectable urinary tobramycin concentrations at or just above the limit of detection for each of the four 12-h collection intervals. These subjects were female and had the same pharmacokinetic profile with the 3 tobramycin doses tested (80, 160, and 320 mg) [17]. In our study, urinary concentration of tobramycin over 6 h probably does not correspond to the total amount of tobramycin absorbed by the lungs, but it was likely sufficient to make a comparison in a same child between the two nebulisation apparatuses, particularly when, as in our study, urine collections over 6 h were complete for all children.…”

“…Tobramycin was chosen to compare the ability of the NL9M and Pari LC+ nebulisers to deliver drugs because it is one of the few drugs which is administered via the airways and it is only absorbed by the lungs without any metabolisation. Urinary excretion is thus total [17]. We preferred to express the amount of tobramycin collected per g of creatinine to limit intra-subject variations, without limiting inter-subject variability.…”

“…The drug used was tobramycin (Tobi®, 300 mg/5 ml solution for inhalation) because, like other aminoglycosides, tobramycin is considered to be a pharmacological tracer of pulmonary deposition [16,17]. In fact, tobramycin is only absorbed by the lungs, without any metabolisation.…”

Assessment of recent nebulizer delivery systems using urinary pharmacokinetics method and aerodynamic characteristics of TOBI ® nebulized dose following inhalation

“…Therefore, in these cases, urine provides useful PK data following inhalation [36,37]. It has been successfully employed in the determination of the relative lung bioavailability of many inhaled drugs, such as salbutamol [38], sodium cromoglycate [39], nedocromil sodium [40], inhaled gentamicin [41,42] and inhaled tobramycin [43].…”