Acute Relief of Exercise-Induced Bronchoconstriction by Inhaled Formoterol in Children With Persistent Asthma: FEVj
FEV1 before (baseline) and 5 min after (predose) exercise are shown in Table 2 together with the percentage drop between these two time points. The drop during the formoterol day (26.4%) most resembled the drop during the screening day (25.5%) but was statistically significantly smaller than during the placebo day (37.3%; p = 0.001). The drop on the terbutaline day (31.6%) was between and not statistically significantly different from either. The order in which treatment days were performed did not influence the drop in FEV1.
The time profile of mean FEV1 is shown in Figure 2. Both formoterol and terbutaline showed statistically significantly larger improvements than placebo at all time points (Table 3). No difference was found between terbutaline and formoterol for the primary outcome parameter (FEV1 at 5 min; p = 0.15), but the difference reached statistical significance in favor of terbutaline at 3 min and 10 min (both p = 0.04), The mean FEV1 at 5 min expressed as percentage of the maximum increase during the 60 min following drug administration were 62% (formoterol), 62% (terbutaline), and 24% (placebo). Source
A Kaplan-Meier plot of time from drug administration until FEV1 had reached within 5% of baseline FEV1 is shown in Figure 3. Median recovery times were 5.0 min (formoterol), 7.4 min (terbutaline), and 44 min (placebo). The difference between formot-erol and terbutaline was not statistically significant (p = 0.33). In total 23 of 24 formoterol patients, 24 of 24 terbutaline patients, and 15 of 23 placebo patients reached the recovery limit within 60 min after drug administration. The time profiles of mean MMEF25-75 for formot-erol, terbutaline, and placebo were similar to those of FEV1. Both formoterol and terbutaline produced statistically significantly larger improvements than placebo 3 min, 5 min, 10 min, and 60 min after drug administration (p < 0.001 for all) but with no difference between formoterol and terbutaline. Both formoterol and terbutaline provided relief from EIB, with statistically significantly larger improvements than placebo at all time points (3 min, 5 min, 10 min, and 60 min after drug administration), as measured by both FEV1 and MMEF25-75.
Table 2—FEVj Before and After Exercise Testing
|Variables||Screening Day (n = 24)||Randomized Part of the Study|
|I Formoterol Day (n = 24)||Terbutaline Day (n = 24)||I Placebo Day (n = 23)|
|Baseline FEVb L||2.58(1.24-4.24)||2.65 (1.29-4.73)||2.58(1.28-4.46)||2.54(1.11-4.97)|
|Predose FEVb Lft||1.92 (0.87-3.48)||1.93 (0.89-3.74)||1.76 (0.63-3.74)||1.56 (0.62-2.84)|
|Fall in FEVj, %|||25.5 (5.2-65.3)||26.4 (10.4-56.4)§||31.6 (9.5-63.8)|||37.3 (15.7-62.9)|
Table 3—Analysis of FEVj
|Ratio, %||I 95% Confidence Limit||Ratio, %||I 95% Confidence Limit||Ratio, %||I 95% Confidence Limit|
Figure 2. Mean value curves for FEV,. adm = administration.
Figure 3. Kaplan-Meier plot of time to recovery (within 5% of baseline FEVj.