Concentration profile of tobramycin in exhaled breath condensate after inhalation of a single dose: A pilot study

Exhaled breath condensate (EBC) has recently emerged as a noninvasive alternative to obtain a respiratory sample to study airway drug concentration. The aim of this work is to explore the feasibility of EBC to measure tobramycin concentration using a synthesized sodium dodecyl sulfate-capped silver nanoprobe as a pilot study. In this study, EBC was collected from healthy volunteers using a lab-made setup after inhalation of 150 mg tobramycin to obtain a full concentration-time curve. Tobramycin concentration in EBC was measured by a synthesized sodium dodecyl sulfate-capped silver nanoparticle probe using λ₅₂₂/λ₄₀₀ UV absorption ratio on UV–Vis spectrophotometer. Tobramycin was detectable in EBC 4 h post inhalation with a limit of detection of 0.5 ng/mL. Mean (SD) C_max and AUC_last were 31.5 (6.8) ng/mL and 53.2 (25.5) ng.h/mL, respectively. Results demonstrate the possibility of investigating the bioequivalency of inhaled formulations of tobramycin employing EBC samples.