Differences in Inhaled Fluticasone Bioavailability Between Holding Chambers in Children with Asthma

STUDY OBJECTIVE: To determine if differences between holding chambers in previous in vitro aerosol studies would agree with the bioavailability of inhaled fluticasone propionate between the same holding chambers in children with asthma. DESIGN: Double-blind, randomized, crossover study SETTING: University of Florida Clinical Research Center. PATIENTS: Eight children (aged 5-9 yrs) with stable asthma. INTERVENTION: Under observation, the children inhaled two 110-microg puffs of fluticasone twice/day through the InspirEase or E-Z Spacer holding chamber. MEASUREMENTS AND MAIN RESULTS: Blood samples were collected at baseline and then at 0.5, 1, 1.5, 2, 4, and 6 hours after the last dose of fluticasone. Primary outcome measures were peak fluticasone steady-state plasma concentration (Cmax) and area under the fluticasone plasma concentration-time curve from 0-6 hours (AUC0-6). The fluticasone plasma concentrations were determined by high-performance liquid chromatography-mass spectrometric assay. Mean +/- SD Cmax from InspirEase (245 +/- 77 pg/ml) was 18% higher than that after E-Z Spacer (199 +/- 58 pg/ml, p < 0.05). Mean +/- SD AUC0-6 from InspirEase (1103 +/- 305 pg x hr(-1) x ml(-1) was 22% higher than that delivered from E-Z Spacer (863 +/- 258 pg x hr(-1) x ml(-1), p = 0.06). CONCLUSION: Differences in inhaled fluticasone bioavailability between these holding chambers in children with asthma corroborate differences reported in earlier in vitro aerosol studies.