The determination of budesonide and fluticasone in human sputum samples collected from COPD patients using LC–MS/MS

A bioanalytical method for the quantitative determination of budesonide and fluticasone in human sputum was developed. Sputolysin® Reagent was added to the sputum samples. After incubation (37 °C; 60–70 min under shaking) and automated solid phase extraction the extracts were analysed using LC–MS/MS. Budesonide and fluticasone showed good linearity (r > 0.99) over the range 0.1–100 nM in the first and second validation batch, and over the range 0.25–10,000 nM in the third and fourth validation batch. The lower limit of quantification (LLOQ) achieved was 5 nM for budesonide and fluticasone in 100 μL human sputum. Intra-run and inter-run RSD for four quality control levels (5–100 nM) were within 6.9% (budesonide) and 8.0% (fluticasone). The accuracy ranged from −11.4% to −1.6% (budesonide), and from −11.8% to 0.4% (fluticasone). The validated method was applied to clinical sputum samples from COPD patients.