In vitro Performance Assessment of Recent Nebuliser Delivery Systems for Nebulisation of Approved Aerosolised Tobramycin (TOBI)®

Abstract

TOBI® is a recently marketed preservative and sulphate free tobramycin formulation approved by FDA for maintenance therapy for patient with cystic fibrosis. The performance of selected recent nebuliser delivery systems has been assessed using the developed method to determine the optimum combinations to deliver approved tobramycin inhaled solution (TOBI)®. A simple, sensitive and specific high performance liquid chromatographic method has been developed and used to quantitative determination of the aminoglycoside tobramycin following pre-column derivatisation with phenylisocyanate (PIC). The reaction time was 10 min at 80º C and the resulting derivative was stable for five days at room temperature. The quantitative performance of the assay was further improved by using another aminoglycoside (neomycin) as internal standard. The stable resulting PIC-tobramycin derivative was separated using a HPLC 5μm Columbus C18 column (150x4.60 mm i.d, Phenomenex). The mobile phase was consisted of acetonitrile-glacial acetic acid-water (450:5:545, v/v/v) and ultraviolet detection at (240 nm). The proposed method showed good validation data. The standard curve was linear (n=5) at seven different concentrations, ranging from 20 to 140μg/ml and the correlation coefficient (R2) of the regression line was 0.9995. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.86μg/ml and 2.62μg/ml, respectively. The relative standard deviation (RSD %) was less than 0.6% for intra-day assay (n=5) and 2.5% for inter-day assay (n=5). A number of nebuliser performance comparison studies have been demonstrated for aerosolise TOBI® to choice the optimum combination produces high repirable inhaled mass of tobramycin. The objective of this study was to evaluate the performance of recent nebuliser delivery systems to nebulise approved tobramycin inhaled solution (TOBI)®.