Dose-response relationship and reproducibility of the fall in exhaled nitric oxide after inhaled beclomethasone dipropionate therapy in asthma patients

Study objectives: The fractional concentration of exhaled nitric oxide (FENO) is a marker of asthmatic airway inflammation. We determined the dose response and the reproducibility of the FENO fall following inhaled beclomethasone dipropionate (iBDP) therapy in nonsteroid-treated asthmatic patients. Study design: Study A: For four 1-week periods (period 1 to period 4), the following regimens were administered in sequential order to 15 nonsteroid-treated asthmatic patients: period 1, placebo; period 2,100 mug/d of iBDP; period 3, 400 mug/D of iBDP; and period 4, 800 mug/d of iBDP. Spirometry, FENO, and provocative concentration of methacholine resulting in a 20% fall in FEV1 (PC20) were measured at each of five visits (visit 1 to visit 5). Study B: During four periods, 12 nonsteroid-treated asthmatic patients received placebo treatment for 7 days (period. 1), 200 mug/d of iBDP for 14 days (period 2), washout on placebo treatment until the FENO was within 15% of baseline (period 3), and 200 mug/d of iBDP for 14 days (period 4). Results: Study A: Mean FEV1 rose progressively from 3.10 L (visit 1) to 3.41 L (visit 5; p = 0.001). Ah iBDP doses caused a significant FEV1 rise compared to placebo treatment, but with no significant separation of doses using FEV1. FENO geometric mean (95% confidence limits) fell progressively from 103.5 parts per billion (ppb) (78.5 to 136.7) to 37.4 ppb (29.1 to 48.0) from visit I to visit 5 (p = 0.001). Ah doses of iBDP resulted in a significant change in FENO from placebo treatment, but with significant separation of only the 100-mug and 800-mug doses by FENO. Geometric mean (95% confidence limits) PC20 rose progressively from 0.01 mg/mL (0.00 to 0.19) to 0.48 mg/mL (0.01 to 8.1) from visit 1 to visit 5 (p = 0.002). All doses of iBDP resulted in a significant change in PC20 from baseline or placebo treatment, but with no significant separation of active iBDP doses using PC20. Study B: FENO fell from 111.56 ppb (80.3 to 155.1) to 66.3 ppb (49.2 to 89.5; p < 0.001) from period 1 to period 2, and from 110.2 ppb (79.3 to 153.1) to 61.7 ppb (42.9 to 88.8; p < 0.001) from period 3 to period 4, There were no significant differences between FENO in period 1 and period 3 (p = 0.83) or between period 2 and period 4 (p = 0.220). Conclusions: FENO was superior to FEV1 and PC20 in separating doses of iBDP. The fall in FENO after two identical administrations of iBDP separated by placebo washout was highly reproducible.