The influence of ipratropium bromide in the recovery phase of methacholine induced-bronchospasm.

BACKGROUND

The protective effect of Ipratropium Bromide (IB) in the methacholine-induced bronchospasm is well known from some time. The objective of the present study was to assess whether a pretreatment with IB may influence the subsequent phase of methacholine-induced bronchospasm relief.

METHODS

Sixteen patients with bronchial hyper-reactivity (PD20 FEV1 < 200 microg) were randomly assigned to three methacholine challenge tests at a 48 to 72 hours interval apart. In the first test IB was inhaled before the challenge (pre-IB), in the second IB was administered soon after the PD20 FEV1 (post-IB), and in the third no treatment was given (control).

RESULTS

The pre-IB PD20 FEV1 (695 +/- 587.6 microg) was significantly greater (p < 0.0001) than that of post-IB (82.2 +/- 49.18 microg) and of control (73.9 +/- 41.8 microg). The dose response slope (DRS) (decline percentage of FEV1/cumulative methacholine dose), in pre-IB was greatly lower (p < 0.0001) than that in post-IB and in control. During the bronchospasm relief phase, the increase of FEV1 measured after 5, 10, 15, 30 and 60 minutes from the PD20 FEV1 was significantly greater in post-IB (p < 0.05) compared with the other two conditions. Conversely, the recovery slope (RS) (increase percentage of FEV1 at 60 minutes after PD20 FEV1 x cumulative methacholine dose) was significantly more efficient (p < 0.001) in pre-IB than in post-IB and in control.

CONCLUSION

In conclusion, ipratropium bromide confirmed to have a good protective activity against methacholine-induced bronchospasm; the pre-administration of ipratropium bromide showed also a positive effect on the recovery phase.