Plasma concentrations of inhaled corticosteroids in relation to airflow obstruction in asthma.

AIMS: To compare the pharmacokinetic profiles of beclometasone, budesonide, fluticasone and mometasone following inhalation in patients with asthma, and explore the relationship between lung function and plasma drug concentrations.
METHODS: Thirty subjects with asthma and a forced expiratory volume in 1 s (FEV(1)) ranging from 36 to 138% predicted, inhaled 800 microg beclometasone, budesonide and mometasone and 1000 microg fluticasone in random order. Plasma drug concentrations were measured over 8 h and the relationship between the area under the plasma concentration-time curve (AUC(0-8)) and lung function was modelled using linear regression. Estimated AUC(0-8) values at 50 and 100% predicted FEV(1) were compared for each drug.
RESULTS: Pharmacokinetic profiles differed markedly between the drugs. Correlation coefficients for the relation between FEV(1)% predicted and AUC(0-8) values for beclometasone, budesonide, fluticasone and mometasone were 0.37 (P = 0.05), 0.33 (P = 0.08), 0.25 (P = 0.2) and 0.52 (P = 0.004), respectively, and estimated AUC(0-8) values were 1.3 [95% confidence interval (CI) 1.0, 1.8], 1.3 (95% CI 1.0, 1.8), 1.4 (95% CI 0.9, 2.2) and 2.2 (95% CI 1.3, 3.5) times higher for the four drugs, respectively, at 100 compared with 50% predicted FEV(1.)
CONCLUSION: The higher plasma concentrations of inhaled corticosteroids in patients with a higher FEV(1)% predicted suggests that, for any given dose, these patients will be at greater risk of developing adverse systemic effects with long-term use.

RCT Entities:   Population Interventions Outcomes